200 Stories of aircraft building


Below are 200 stories on aircraft building that I wrote in the last 2.5 years. This is just the top 40% most popular ones from our blog. They are loosely grouped, but you can scan through the titles, and you can read the full story by clicking on any colored title.

There are some real classics like “Unicorns vs Ponies”, but most stories are directly about flying planes and running engines. You don’t have to read it in one sitting (it is about 250,000 words, half the length of “War and Peace“) But keep it handy for a reference page. -ww.



Basic Corvair information

Shop perspective: Mastery or ?

Concerned about your potential?

A visit to the insane asylum

Glider flying – a funny story

The Cherry Grove Trophy

Model T of the air?

Model T of the air, Part #2 – Leeon Davis notes

More Thoughts On Economical Aircraft

Testing and Data Collection reference page

Why Not the Panther engine?

What is a core engine worth?

Corvair College reference page

Corvair College History….in photos

College Tech

Basic Corvair College Skills, examples of learning

Zenvair’ Information board formed

Calling All “Zenvair” Flyers……601 / 650 / 750

New Numbering System, Final, please print.

College engine build options for closing the case

Getting Started in 2013, part #1, Crankshaft process options.

Getting Started in 2013, Part #2, Group numbering system

Getting Started in 2013, Part #3, The Camshaft Group (1100)

Getting Started in 2013, Part #4, Case Group (1200)

Getting Started in 2013, Part #5, ‘Allan Able’ short block.

Getting Started in 2013, Part #6, ‘Bob Baker’ short block

Getting Started in 2013, Part #7, ‘Chas. Charlie’ Short Block

Getting Started in 2013, Part #8, ‘Davie Dog’ Short Block

Getting Started in 2013, Part #9, ‘Eddie Easy’ short block.

Getting Started in 2013, Part #10, Piston and Cylinder options.

Getting started in 2013, Part #11, Comment of the day

Getting Started in 2013, Part #12, Piston Choices

Getting Started in 2013, Part #13, Basic piston/rod/cylinder combo.

Getting Started in 2013, Part #14, 2,850 cc piston/rod/cyl. Kits

Getting Started in 2013, Part #15, 2,775cc, (imaginary piston)

Getting Started in 2013, Part #16, 3,000 cc Piston/cylinder kits

Getting Started in 2013, Part #17, Short block cost chart.

Getting Started in 2013, Part #18, A look ahead

Getting Started in 2013, Part #19, Cylinder Heads

Guest Writer: Pietenpol builder/flyer Kevin Purtee

Guest Editorial, Arnold Holmes On Affordable Aircraft…



Planes flying on Corvair Power

Corvair planes and projects on You Tube

Corvair Powered Davis DA-2, w/EFI

List of Corvair Powered Zeniths

Zenith 750 / Corvair reference page, October 2013

Zenith 601/650 – Corvair reference page November 2013

Corvair power for Panther and Sonex reference page

Pietenpol review in pictures, 15 more Corvair powered Piets

16 Flying Corvair powered Zenith 601/ 650s

Corvair – Pietenpol Reference page

Gary Burdett, 2,850cc Zenith 750, now flying. (engine selection)

New 3,000 cc Cleanex, Dale Williams, SC

Panther Roll out.

Zenith 701- Corvair reference page, November 2013

New Photos of JAG-2, a Corvair powered twin.

JAG-2, Corvair Powered Twin, Jim Tomaszewski, N.Y.

Zenith 601XL-3100cc Dr. Andy Elliott

Zenith 601XL-2,850cc, Woody Harris

Zenith 650-2700cc Dave Gardea

2,700cc-Skycoupe-2002 Photos

New “Zenvair-750″, Jeff Cochran, 2,850cc engine, N750ZV

Flying Zenith 750 w/3000cc Corvair, Doug Stevenson, California

Corvair powered Dragonfly, Charlie Johnson, aka ‘One Sky Dog’

Zenith 750 Flying on Corvair Power, Gary Burdett, Illinois

KR-2S at 700 Hours – Joe Horton

New Zenith 601 XL(B), Conventional Gear, Jerry Baak, S.C.

New Pietenpol, 2700 Corvair, Don Harper SC

New Pietenpol, Gary Boothe, Cool, Calif.

Two More Flying Planes: Merlin and VP-2

Corvair Powered Merlin Flying Over Newfoundland

Floats on Snow, Corvair powered Merlin

Flying 2,850cc Cleanex, Clarence Dunkerley

New Pietenpol, EAA #1279, French Valley CA

New Pietenpol #3, Mike Groah, Tulare, California

Guest writer: Phil Maxson, flying a 3100cc Corvair in his 601XL

Another new “Zenvair” 601XLB, Jim Ballew, 2700cc

Flying Zenith 750, Tom Siminski, 2700cc, PA.

Flying 2700 cc Zenith 601 XL(B), Alan Uhr



Complete Engines for Sale

2012 Corvair Engines For Sale: 100, 110 and 120 HP

World’s Strongest 3,000cc Corvair, built by Greg Crouchley

Panther Prototype Engine 3,000 cc/120 hp to OSH

3,000 vs 3,100 cc Corvair engines

3,000cc/Billet Crank Shortblock, Destination: Waiex

High Volume Oil Pump

3,000cc Engine Running

3,000cc Case Modifications.

Billet Cranks Made In The USA

Chinese Crankshafts

Chinese Crankshafts for Corvairs, update 2/17/13.

Notes on Corvair flight engine oils.

Shipman Engine at CC#22

A Tale of Two Spark Plugs……

The Panther’s engine, worlds strongest Corvair flight engine.

Panther Engine Is Alive … ALIVE

Engine Operations reference page

The case of the Murphy Rebel, “eyeball vs. testing”

Corvair vs O-200…. weight comparison

Testing Head Studs

Balancer Installation

Gold Oil Filter Housing, Standard and Reverse

Front and Rear alternators, their part in numbering system

Thoughts on cold weather operation, minimum oil temps, etc.

Cooling with J-3 style cowls. (Pietenpols, Cubs, Biplanes, etc)

Spark Plug Installation

Starting procedures on Corvairs, 2,000 words of experience.



Stromberg Carbs

Carb applications, choices people make

Fuel Injected Corvairs

Carburetor Reference page

A question of Carb location…..

Mechanical Fuel Injection Testing

Stainless Steel Exhaust Systems

Fuel Injection – Corvair flight engines reference page

New die spring landing gear on a Pietenpol, 10 a.m.-4 p.m.

Pietenpol Products, Motor mounts, Gear and Instalation Components.

MA3-spa carb pictures, Wagabond notes.

In Search Of … The Economical Carburetor

Pietenpol Box Spar Construction, 6/27/13

Pietenpol Mount on airframe

Panther Engine propeller test

Kitfox Model IV with Corvair mount

Corvair Motor Mount for Bearhawk LSA

Inexpensive Panel……..part one.

Inexpensive panel…….part two.

“William, you ignorant troglodyte”…….(instrument options)

My favorite Tach; Stewart Warner 82636.

Ammeters Pro and Con, & Flying like there is no tomorrow.

Corvair Oil System, information on oil pressure gauges.

MGL vs Corvair ignition issue

Measuring Cylinder Head Temps on Corvairs.

Corvair Cooling

Corvair Cooling, Three 2007 examples from our hangar.

Cylinder Head Temperature measurement

Cowling Inlet Area, marketing, accident stats, Darwin where are you?

Corvair Cooling, something of a human issue…..

CHT part #5, flight data from Zenith 750

Engine Cooling Factory Sheet Metal

Pietenpol Fuel lines and Cabanes

Three Pietenpol Motor Mounts

Zenith 601/650 Motor mounts, P/N 4201(A)

Intakes and Internet myths



Welcome to The FlyCorvair.net Blog

Back from the road, notes on Communications



Unicorns vs Ponies.

Sunday, a long day at the airport.

Fixing America is going to cost each of us $1.69

Greatest Book on Flying Ever Written, (Is your life worth $16?)

A thought on Easter….

In defense of plain speaking……

Turtles and Cell Phones, 6/24/13.

2,500 words about levels of aircraft finsh……

Steel tube fuselages, “Safe” planes and 250mph accidents

Cessna’s Chinese adventure a failure.

Communist Chinese government at Oshkosh

Risk Management, Experience vs Judgement.

Risk Management, Wrong airframe, Wrong experience level.

Effective Risk Management – 2,903 words

Risk Management, Factor #1, Judgement.

“If only someone had told him……”

Expert Witnesses in civil Aviation trials.

Great tales from discussion groups…….part #1

Vern’s Aero-Cars

Fun with Agkistrodon Piscivorus and Vern’s Aero-Trike

Cloudn’t have happened to a nicer guy……

Built by William Wynne? Built according to The Manual?

Risk Management, Judgement Error, money in the wrong place.

Flathead Ford, 71 cid. Freedom to pursue happiness.


History and aviators:

B.H. Pietenpol, Patron Saint of Homebuilding

Robert Hedrix, Aviator, Nha Trang, 1975

The Quote, 1927, C.A.L.

James Stockdale – Philosophy

Sterling Hayden – Philosophy

A Father’s Day Story – Lance Sijan

Three Aviation Stories

Charles Poland Jr., An American of whom you could be proud.

Carl Sagan, Corvair Owner, Practical Philosopher, Individual.

William Edward Wynne Sr. – Father’s Day Notes



Corvair College #22, March 9-11, 2012 in Austin, Texas

Panther Prototype Engine 3,000 cc/120 hp to OSH

John Moyle, noted aviation enthusiast, passes -1/16/13

Corvair College #25, In Photos

Corvair College #23 – 2850cc Engine, Roger Grable, CH-750 Builder

House Call on Pat Green’s 1,000 Hour Pietenpol

Brodhead, Oshkosh and Beyond 2013

Wisconsin 2012 Air Adventure

Zenith 750 Builder Blaine Schwartz

Corvair College #23, 2700cc Engine, Spencer Gould, SP-500

Sun N Fun 2012

Randy Bush’s Pietenpol hits 500 hours.

Corvair College #27 run on film

Franklin Engine Runs at CC ##22 KGTU Spring Break 2012



Zenvairs ruled the skies over the northeast!


The title above was sent in with this photo by Ken Pavlou. He now has just about completed his phase one testing, and it has gone without a single flaw. Ken organized two other Corvair/Zenith pilots to fly in a formation around his area over the weekend. Below is a photo of all three on the ramp.



Left to right, Three Corvair powered Zenith 601XL’s. Ken Pavlou, Rodger Pritchard and Louis Leung’s planes in a row. Ken said the flight was a lot of fun and a nice way to conclude phase one.


All three of these Northeast builders attended Corvair College #14 in Lowell MA. Both Rodger and Louis have flown their planes to Oshkosh.  All three of the planes are powered by 100 HP, 2,700 cc standard Corvair engines, all assembled, maintained and mastered by each of these builders. There are many engine options available to Zenith builders, but the Corvair offers a unique combination of affordability and the opportunity to become an expert on your power plant, not just it’s owner.


To learn more about the combination, click on:

Zenith 601/650 – Corvair reference page November 2013




More stories on Zenith 601s and 650′s, click on any title to read:

16 Flying Corvair powered Zenith 601/ 650s

Woody’s 2,850cc Corvair/601XL hits 400 hours.

New Zenith 601 XL(B), Conventional Gear, Jerry Baak, S.C.

Flying 2700 cc Zenith 601 XL(B), Alan Uhr

 Zenith 650-2700cc Dave Gardea

 Zenith 601XL-2,850cc, Woody Harris

Another new “Zenvair” 601XLB, Jim Ballew, 2700cc

Second “Zenvair”, the McDaniel’s 2700cc 601XLB

 Patrick Hoyt, new Zenith 601XL, now flying, N-63PZ

Guest writer: Phil Maxson, flying a 3100cc Corvair in his 601XL

 601XL-2700cc Dr. Gary Ray

 Zenith 601XL-3100cc Dr. Andy Elliott






Photos from CC#14 – Lowell MA – click on links:







Thought for the day: “Censorship” on the net

“If your reading this, and you have never met me, let me teach you one single important thing right now that most people don’t yet know: Censorship is the rank amateur way of controlling people. It is not effective at all, especially in the information age. However, it has three highly effective off spring that are the tools of the professionals. These are Disinformation, Self doubt and Fear. These three are far more effective, and they work even when you are later exposed to the truth. If you look at it, negative people out there do all three.  They claim to know of failures, but have no names nor dates; They cite nameless “experts” who disagree with what has been shown to work; they make new builders doubt all the positive and factual reports, and gradually over years, they get you to be afraid to trust things that have been well proven to work. These efforts would have had little effect on our grandparents, but several decades of intense consumer marketing along the same lines makes all of us more prone to distrust, more likely to see some truth in the plausible lie. Unwittingly, many of the people who cry censorship are actually employing  the tools of the real propaganda artist.”




For a number of years I harbored the delusion that I could participate in on-line aircraft discussion groups, and write some things that would allow new builders to understand that we had pioneered  very effective and reliable ways to build an operate Corvair flight engines. I freely admit that I was wrong. On any discussion group where people who are known only was “Flyboy26” or “RVguyCN” have the exact same size soap box as people with real names, specific experience, links to photos, there is no chance for new people to sort useful reality from dangerous fiction.


On discussion groups I tried to advocate that people should use real names and they should never ‘recommend’ anything that they had not personally and specifically flown behind. I also advocated that all references to third party experts, require also stating that persons name, so people couldn’t say things like “A local expert here who has built 25 planes says that will not work.” These sounded like very reasonable ideas to me if we were going to talk about Corvair engines in planes for the purpose of getting people flying. I was wrong about that, and a number of very vocal people always claimed that I was “Censoring” them buy not supporting their ‘right’ to say anything.


As you might imagine, I was quite a thorn in the side of people like ‘flyboy26’. I merely showed how things they advocated had long been proven by our testing not to work. Over time, these people hated me. They switched tactics to making wild claims about our products failing, they claimed to be in touch with ‘experts’ who assured them that a wave of failures was eminent, and they constantly tried to make people afraid to follow things we had long proven to work.


These tactics didn’t win builders to their ideas, but they were very effective in getting a large number of new builders to do nothing. Probably without knowing it, ‘flyboy26’ and his buddies were employing real propaganda tools, Disinformation, Self doubt and Fear. Before getting kicked off discussion groups for life, I wrote the quote above in hopes that new builders would understand.  I look back today and see that hope as delusional also.





Left to right, Three Corvair powered Zenith 601XL’s. Ken Pavlou, Roger Pritchard and Louis Leung’s planes in a row. Ken’s plane had just concluded phase one, 40 hours without the slightest issue, or need for adjustment. Roger and Louis have already flown their planes to Oshkosh. The builders of these planes are all members of a private discussion group that I formed as an alternative to open internet groups that allow comments from ilk such as ‘flyboy26’. You can read about the group at these two links:


‘Zenvair’ Information board formed


‘Zenvair’ information board, part #2


Ken had never built a plane nor engine before. The reason why his flight testing was without event, is because he followed our proven path, and took no advice from internet ‘experts’. The same week that Ken flew off his last hour, another 601 with a Corvair in it took it’s first flight.  That builder chose to listen to many people, but follow very little that I had to say.


His first flight lasted just 6 minutes, one trip around the pattern. Many of the things this man tried, like cooling plenums on the engine and a carb off an old British car, were championed by people on open discussion groups, the same people who called me a Censor for pointing out they had never tried what they advocated. When the builder got on the ground 6 minutes later, 1/10 of an hour, 1/400th of his testing done, perhaps he had greater respect for my efforts to ‘censor’ the speech of dangerous fools.




STOL and utility planes for Corvair power


Below is an overview of STOL and Utility airframes that have been Corvair powered or are in excellent candidates for the engine, that we have already looked at closely. Included with many of the airframes listed are links to stories about them.


This group of planes are all high-wing cabin monoplanes. There is a good selection of designs for builders to choose from. There are others that would work as well, for example Morgan William’s lite star http://www.customflightltd.com/aircraft-kits-1.html Has flown on Corvair power, but I have just written an overview of the planes most people ask about. If you have a plane in mind that you don’t see here, just send me an email.



Zenith 750:

This is a good match for the Corvair. There have been a number of them flown in the last four years, and many more are in the works. The 750 has flown on 2700, 2850 and 3000 cc Corvairs. We make every part to install the engine on a 750 airframe and have a Zenith specific install manual. The last link below has a very complete over view.



Above, the flying 2850cc Zenith 750 built by Gary Burdett of Illinois.  It has our full complement of Zenith installation components and one of our production engines.


Zenith 750 Flying on Corvair Power, Gary Burdett, Illinois

Flying  Zenith 750, Tom Siminski, 2700cc, PA.

Flying Zenith 750 w/3000cc Corvair, Doug Stevenson, California

New “Zenvair-750″, Jeff Cochran, 2,850cc engine, N750ZV

 Zenith 750 / Corvair reference page, October 2013


Zenith 701:

We flew our 701/2700cc Corvair test bed aircraft in 2007.  The combination works, and a few have been built, but the 750 has stolen a lot of the potential popularity. If anyone is looking at both airframes, they should pick the 750, because it has matched hole tooling and is far easier to build. It is a better match to a Corvair. Economically, a Corvair powered 750 will still cost a lot less than a 912 powered 701. The link below the photo has a very detailed look at the combo. The plane below was made of all our off the shelf engine components, and the entire plane and engine was built in our Edgewater hangar.


Our Corvair powered 701 taxis out before its first flight, 2007. Gus Warren at the Controls.


Zenith 701- Corvair reference page, November 2013




Is a 20 year old Canadian design with automatic leading edge slats. It has a metal wing and a steel tube fuselage. We finished and flew the first Corvair powered on in 2007. the story is in the link below the photo. The engine has all of our conversion components. Every part ahead of the firewall was built in our hangar in Edgewater.


Read the story at this link:

3,100cc Corvair in Pegzair



Wagabond :

Below, our Wagabond, N707SV, flying over the Intercostal Waterway near the Atlantic Ocean in 2005. The airframe is based on a highly modified 1964 Piper PA-22-108 (Colt). The plane was built as a group project by “The Hangar Gang” between 2003 and 2005. It has been flown by a number of well-known Corvair pilots who all found it to be a well behaved work horse. In person, the plane is very large for an LSA legal homebuilt. The airframe is the size of a Tripacer, and sitting on the ground the spinner is as tall as I am, yet a direct drive 100 HP Corvair easily flys this plane, including a test flight where the plane climbed out with a payload greater than its own empty weight.

Originally flown to shows by David Vargesko, today the plane has been modified and refined by Grace and myself, re-engined with a 120 HP 3000 cc Corvair, and functions as our personal Corvair powered plane. It is a 5 gallon per hour, 100 MPH plane with a very large baggage compartment. With Grace, the dog, myself and 36 gallons of fuel loaded, it can still carry 275 pounds of equipment and stay in CG.


Below is a youtube link to the plane flying:





Below is a link to film of Jeff Moore’s Merlin flying on floats in Newfoundland. The airframe has a strong following in Canada. This particular plane was originally powered with a Rotax. Jeff’s plane uses most of our Gold engine parts and one of our stainless U-2 exhaust systems. The engine is a 2700 cc motor with a Weseman 5th Bearing.


Jeff and the Merlin with Corvair installed.



Jeff’s story is at this link:

Corvair Powered Merlin Flying Over Newfoundland




The plane was originally Designed by Steve Wittman in 1937. It was vastly ahead of its time. Later modified to have full span movable leading edges.  Grace and I worked on the Buttercup pictured below with the intention of finishing it for ourselves before we had a change in direction. Our standard intake and U-2 exhaust fits the plane, along with all of our gold engine components.

Above, the motor mount for our Wittman Buttercup. It is an intensely complicated mount because it incorporates Wittman’s tapered rod landing gear sockets (the modern Buttercup actually uses RV-6 landing gear legs). Earl Luce, the plans provider gave me all the operational data and weight and balance info for his O-200 powered plane, which I mathematically worked out to the Corvair installation. The Mount resembles the O-300 mount for a Tailwind.  After completely welding it, I took it to our local powder coater, and had it done in U.S. Navy gray. It was the 40th different Corvair Motor Mount Design that I have built. Today two builders are closing in on finishing the Corvair Buttercup combination, but none have flown yet. The plane above is being finished in Wisconsin.




The Murphy rebel is an all sheet metal Canadian design almost 25 years old. It is not currently in production. It is a complicated plane to build compared to other all metal designs like a Zenith. Below is a link to a story I wrote about how people who know nothing often say the Corvair will not work on utility planes like the rebel, in spite of all the evidence on this page that speaks to the contrary. The commentary and data in the story is worth reading for anyone looking at a Corvair engine for their homebuilt.

The case of the Murphy Rebel, “eyeball vs. testing”



Bearhawk LSA:

I consider this plane to be the best flying plane in it’s category. I worked directly with the designer Bob Barrows to develop a Corvair motor mount for it. I flew Bob’s prototype, and it has excellent handling qualities. The design uses or standard intake manifold, and a stainless exhaust common to our Zenith installation.


Corvair Motor Mount for Bearhawk LSA

Bearhawk LSA, Corvair motor mount in development

Bob Barrows to Fly LSA Bearhawk to CC #27, Barnwell, S.C., Nov. 2013




The only Kitfox model that has flown with a Corvair was the model 5. The builder had a number of issues, related to using a poor choice in carbs. Below is a link to a Kitfox 4 mount we made in my shop. The engine is slightly too big for the model 4, but it is a good match for the series 5 and up.  The factory likes to promote engines they sell cowls for and have a dealership on.  Kitfox has had three different owners in the last 25 years. The current ones did not sell the bulk of the unfinished model 5’s which are available second hand from internet sources like barnstormers.com for less than 50% of their original sale price. Combine one of these with a Basic Corvair, and it is possible to build a good plane for less than $18K, airframe and engine.


Kitfox Model IV with Corvair mount


Stits SA-7D Skycoupe:

Ray Stits, the man behind the fabric covering system designed a series of very successful planes in the late 1950s. The Skycoupe was once one of the most popular 2 seat planes in the EAA.  Several hundred were built, and their was even a FAR-23 type certified model. It is a stout plane, but it is small inside by modern standards. We put about 200 hours of flight testing on ours, it is a natural match for the Corvair. Below the photo is a link to pictures of turbocharging the design.


Above, the Skycoupe on the ramp in front of our Edgewater hangar in 2007. We made every component ahead of the firewall on this plane.


Read more at this link:

More Turbo Skycoupe photos



Fisher Horizon 1 and 2:

Both of these designs have flown on Corvair power. I built the motor mount for them, and most of our off the shelf components fit the installation.  The plane has strong appeal for builders who like wood, but it is not as rugged as steel tube designs or all aluminum ones.



The first plane ever to fly with a Corvair was a J-3 in 1960.  The Corvair would make a very good power plant for any of the J-3, J-5, PA-12 family of airframes.


Just Highlander:

Below is a photo of the first Corvair/highlander to fly. It was not a success because the builder insisted on using a left over cowl from a Jabaru 3300, and the Bing Carb from the same engine. He also ran the engine was a display without any form of cooling for a long period on the ground prior to the first flight.  With the wrong cowl and carb, it should come as no surprise that the plane overheated. From the pictures above, we have plenty of evidence that the Corvair can easily power larger heaver and slower planes than the Highlander when it is equipped with the correct cowl and carb. .




Is an older design that is somewhat similar to a champ. The plane has many fans, but it would not be my first choice in a utility plane. It is called a STOL plane, and it is by Lancair standards by not by Zenith standards. The plane pictured below was powered by a 2700 Corvair with a Rinker Gearbox, a design from the 1970’s. The gear box failed in 28 hours because the machinist employed by the builder decided to omit a keyway critical to the design. The combination will work much better as a direct drive plane.




Taylorcraft BC-12D replica:

Below is a one of a kind plane, built from some BC-12D parts. Today the FAA has cracked down on this practice, but with a friendly DAR this could still be made. The plane below is powered by a 2700 and has clipped wings. It topped out at 130mph.



This very slick aircraft is the handiwork of Gary Loucks of New York.




Information on Flycorvair.com


To complete the trio of Zenith reference pages, I was working in the middle of last night to put together the one for the 701. We bought our 701 kit in the spring of 2006, flew it in 2007, and wrote a lot of stories about it all the way through its development and eventual modification to include a 5th bearing, It was about 100 hours of flying done by a number of pilots including Gus Warren, Dan Weseman and Arnold Holmes.

In gathering the information, I just went to our main traditional site, Flycorvair.com, went to the bottom of the main page and typed “701” into the plainly marked search box. It spit out links to 24 pages on the site which referenced the 701. Throughout our testing, I did a lot of writing to keep builders posted on what was happening with the project. As raw material, I cut and pasted the data and pictures from these links into my rough draft of the 701 reference page. I was a little surprised to see that flycorvair.com had 56 photos of the plane and more than 10,000 words of description. For scale, consider that when I began my work with Corvairs in 1989, I used the Embry Riddle research library and correspondence with many people to gather every printed word I could find on Corvair flight engines from 1960-89. After 90 days of looking, I was very happy to start with a treasure trove that amounted to 36 printed pages.

Above is a 2007 photo of the 701 airframe under construction in the main Edgewater hangar. It flew by the end of that year.


I bring this up because we get several letters a month from 701 builders asking if anyone has ever put a Corvair on a 701, and how do with think it might work. Obviously, not a single one of these people has typed “701” in the search box on the main page. Granted, the main site is dated, and it needs a house cleaning, but if I had brought that same level of investigation to my 1989 information search, we probably wouldn’t have the Corvair movement we do today.  I consider it odd that the internet, computers and email are all research tools that were beyond my wildest dreams as I sat looking at printed lists of periodical guides in the reference section and used a rotary dialed pay phone to call all the phone numbers I found.  I was using flintlock and long bow technology, compared with todays nuclear weapons grade research tools.

You might suspect that people in general would use these tools and appreciate the vast quantity of information available, but I have ample evidence that the tools and quantity of information have an odd affect of making most people much worse and conducting any kind of investigation. Just consider that  your average person can claim to have done many “Searches” in a single day, as if they were Sherlock Holmes. But in reality, all they did was press a button and had information spoon fed to them my marketing companies that had previously planted spyware on their computers to analyze their buying habits. This really isn’t searching at all. If this type of “investigation” honed peoples detective skills, then they would have long since found their car keys and the TV remote. 

All of this has little effect on people who have no plans to escape the consumer merry-go-round of endless purchases in pursuit of  happiness that will always remain just one more item away. However, if you have formulated a plan to have a better life than that, and track it down and conquer it in the form of building and flying your own aircraft, then improving real research and decision making are in order. Because we all have to take that first step off the carnival ride, I am doing my part to make the first step somewhat easier. I am making the reference pages for popular airframes so that people who are yet to develop the persistence and accurate information skills that builders invariable develop in the process of education and building can more easily find their way into the opportunity of building.  With the focus of mind that comes with taking on a challenge, they will probably remember where they put the car keys. The TV remote will not matter, as people who have a plane to build and a challenge to meet don’t need to waste time in front of the TV set. -ww

Zenith 701- Corvair reference page, November 2013


Here is a single location page that has number of links to information specific to the Zenith 701 / William Wynne-Corvair Combination. In brief, we flew the combination in 2007, and it does work. Our test aircraft weighed 677 pounds ready to fly (without fuel) and more importantly, was well within the CG envelope for the plane, and we didn’t have any ballast in the plane to achieve this. If the number sounds slightly high, consider that we publicly weighed it on electronic scales, and I am reasonably sure that 50% of the empty weights listed for 701’s outright fabrications.

Both the 601 and later the 750 installations we do have been very popular, but the 701 has not proven to be. We have about 12 active builders working on the combination, but it isn’t likely to ever be popular like the 601/750. When people hear this they jump to the conclusion that the 701/Corvair combination didn’t work. They do this without thinking that you can see several examples of Corvair powered 750’s on: Zenith 750 / Corvair reference page, October 2013 and they clearly work, so obviously the same engine will fly an aerodynamically similar plane that is 20% smaller and lighter with 30% less wetted area. The 701/Corvair was not the ultimate performance nor the maximum useful load the 701 could achieve, but it worked well, and it works infinitely better than any engine a builder will never afford. If you would like to start with a simple three page spec sheet on the engine, read this link first: Basic Corvair information


Our Corvair powered 701 taxis out before its first flight, 2007. Gus Warren at the Controls.


The actual reasons why the combination has limited popularity are two fold. First, the 750, it’s newer big brother, is a better plane and product for most builders needs and skills, and it has completely out stripped 701 sales since it’s introduction. Second, 701’s tended to be the project of grass roots- working American builders. The 2008 recession hit these people particularly hard, and they are the last to feel any of the recovery. Many of their projects are dormant while these builders put family first. I encourage all of these men to stick it out. We are here for the long run and will assist them when ever they are ready.

On the mechanical side, one of the cornerstones of our 701 installation is being made of our proven  production parts. The installation uses our regular off the shelf components with only two exceptions, it has it’s own motor mount and its own stainless exhaust system. Even these parts are not totally unique, they are closely related to our other production parts. This commonality allows builders an easer build and installation, and it also means that the track record and flight data from our other flying Zenith installations also benefits 701 builders.

The engine in our 701 test aircraft N-9569S, was a standard 2,700cc production enginebuilt in 2006. We made no attempt to lighten the engine or use special parts, nor did we build a larger displacement engine. We wanted the weight and the performance to represent what a base line builder spending $4,500 to build an engine could expect. Later we installed an Elison Throttle body injector, a Weseman 5th bearing and a larger oil cooler. Even with these developments, a builder could still replicate this engine for $7,400 working from our parts and manual.

While the installation is not “main stream” it is still a viable option, a good match to specific builders. Many new builders get focused on what is popular with most builders. That will work for them also only if they have the same budget, goals and desires as other typical builders. “701 Builders” is a very broad group of individuals, each with their own set of circumstances. If you are one of them, you only need to find the right engine for just one guy in the whole group: You.


Above, the 701 on display in the Zenith booth at Sun N Fun 2010. It was the 7th consecutive year we had a Corvair powered plane on display in the Zenith booth at the airshow. We are supporting Zenith builders for the long run.


This page has an abbreviated look at our Corvair program. For an over view with a little more depth, get a look at either of our other two Zenith reference pages, as they have sections discussing our support programs and a fuller description of the installation components available:


Zenith 750 / Corvair reference page, October 2013


Zenith 601/650 – Corvair reference page November 2013


I will be glad to answer further questions just email WilliamTCA@aol.com or call 904-529-0006. You can also check our two websites, http://flycorvair.net/ , http://flycorvair.com/ . The first is our ‘newspaper’ the second is our ‘library’ and ‘store.’ The links below are stories that already appear on these two sites, they are just arranged here to support this introduction to Corvair power for 701 builders.


The organization of this page follows this outline:


1) – Time line of N9569S, our test bed 701 airframe.

2) – Popular Corvair engine options for Builders

3) – 701/Corvair installation components

4) – Photo essay of our development work on the 701, 2006-2010.

5) – Builders working on the combination

6) – Notes on poor products to avoid



1) – Time line of N9569S, our test bed 701 airframe.


The story started in 2006 when we bought the kit directly from the factory. We were there to hold “Corvair Day”, and we used the occasion to bring home a complete airframe kit. 30 months before in 2003 we had picked up our own personal 601XL  kit, and we had it flying in early 2004. With the 601 program up and running, we decided to try the 701/Corvair combo. We did this with the support of Sebastien Heintz, the president of Zenith. He had a great number of 701 builders who were not comfortable with the escalating costs of Rotax 912’s and he was encouraging people with proven engines to develop affordable installations that would serve his builders.

Sebastien has a simple standard for alternative engine providers: Before they tell his builders how great their engine is for his families airframe designs, they should buy their own, and finish and test it. Sounds simple enough, but 80% of the companies selling engine installations have never owned nor tested the combinations they sell. Some of them have never owned any kind of a test bed aircraft, nor flight tested anything. You would think that no one would buy such products, but people do all the time. Our 701 was the second kit we bought from the factory, and we had a very through in house test program planned.

Picking the kit up in 2006- From right above, Nick and Sebastien Heintz, and Caleb .


In that era we operated with a crew we called “The Hangar Gang.” As a team we had hammered out a string of Corvair R&D projects: My Pietenpol, The Skycoupe, Our 601XL, and the Wagabond, in addition to assisting in completing a number of friend’s Corvair powered planes like Gordon Alexander’s Pegzair and Phil Maxson’s 601XL. I felt pretty sure that we would knock out the 701 in short order,  so that is where we started in the spring of 2006.

 Above, The “Hangar Gang”, with our 601XL, built in 90 days including developing the FWF Corvair installation. The was the first tail wheel XL and the first with dual sticks. The plane was built as an after hours project by 3 or us. L-R, Grace Ellen, myself, Kevin , Whobiscat, Upson, Gus Warren, and Dave the Bear.


Simply put, the 701 came at the wrong time. It took 17 months to finish the plane, an eternity by our standards. We had a lot going on outside the hangar; Four of us got married, 2 bought a house, one had heart surgery, and one got a corporate job. Near the plane being completed, we sold it to a super-wealthy aviation investor who owned a lot of turbine helicopters, but suddenly found himself in need of an LSA plane. The FAA set a Jan, 10th 2008 deadline as the last day you could legally register a professionally built E-SLSA plane, so the arrangement was on the up and up. However it was a poor match because the owner, whom I had known for a number of years, turned out to be the wrong guy to own any plane with the word “experimental” on the registration.

E-LSA was a stupid category for a number of reasons, one of them being it only had a 5 hour test period, not 40. We agreed to do all the flight testing, and Gus Warren did all the first flights. Things went relatively smoothly, but owner had a very different idea of what constituted ‘tested’. We had only one single serious issue where the owner did not set the timing with a light, Gus later did a flight and made a precautionary landing because the engine had way too much advance. Learn a lesson here: all planes need to have only one person in command, and that goes for on the ground also. Neither maintenance nor flight is correctly done by committee.

Over time we worked all the development we needed, and fully turned the plane over to the owner. He had sporadic interest in it. We borrowed the plane back in 2010 and updated it with a big clean up, installed a 5th bearing and took it to Sun N Fun, where we displayed it in the Zenith booth all week. We returned it to the owner, who made some changes I thought were foolish. To my relief, in  2011 the owner said he wanted to sell the FWF. in a week or two we found a 601 builder to buy it. He actually paid the same amount of money I had charged the Zenith owner in 2007. Five years after we picked up the kit at the factory, this closed the R&D part of the 701/Corvair story.

I share this in plain language for several reasons. I want every builder considering the combination to have the full picture, not an industry-typical 4 page brochure with bumper sticker length slogans instead of facts. I also want new builders to understand that even professionals like me make wrong turns and have issues to deal with. If the road to building your own plane has not been perfectly smooth, welcome to the club. Only a person who has never built a plane, or has reason to BS you would claim they never had a detour in plans or an aggravating day. Homebuilding is all about learning, and then putting that understanding into action and material. The people that taught me my skills and what it means to be an aviator were honest and plain spoken, and had little time or tolerance for ‘nice’ and ‘polite.’

After I had been in aviation for 20 years, I made a strong attempt in letter and deed, to thank them individually for what they had shared. For many of them, my expressions of gratitude arrived too late, they had passed. I would never again have a chance to look them in the eye, shake their hand and thank them. I was left with just the hope that emulating their honest and plain spoken ways would respect these men a failed to sincerely thank in person.


The 701 testbed in the Zenith booth at Sun ‘N Fun 2010. This was the last public display of the aircraft. But this time the great interest of Zenith builders had shifted to the 750, and we already had customer-built, Corvair powered 750s being finished.  The project had provided a lot of good data, but it came at a large cost in both dollars and man hours that we knew by 2010 were not going to result in broad sales. This said, the testing, data and combination are all still valid, and can be of use to the right builder.


Above, the 2,700 cc Corvair, in our original configuration on the Zenith 701. An inherently simple engine, It’s opposed six configuration makes it the smoothest of available power plants. It has outstanding cooling because GM put a tremendous amount of cooling fins on it and  gave it a factory CHT redline of 575F. All of our engine parts are made in the United States.


2) – Popular Corvair engine options for Builders


If you are new to Corvairs, lets quickly cover some ground: General  Motors made 1.8 million Corvairs. brand new parts, including billet cranks, forged pistons, valves bearings,  virtually every single part inside is currently made and readily available, and will remain so. Rebuildable Corvair engines are plentiful, and much easier to find that Lycomings or Continentals. We have been working with Corvairs for 25 years, and there is no shortage of core engines or parts. If you doubt this for a second, Google “Corvair engine parts.”

The Corvair makes an outstanding aircraft engine because it is a simple, compact, direct drive, horizontally opposed six cylinder, air cooled engine. It is robust, and ‘flat rated ‘ from it’s automotive output. The engine runs equally well on automotive fuel and 100LL, and it does not care about ethanol. In its 53 year flight history, more than 500 experimental aircraft have flown on Corvair power.

The engine can be built in three dispacements with three respective power outputs. They are 2,700cc / 100HP, 2,850cc / 110HP and 3,000cc / 120HP. The two smaller displacements weigh 230 pounds, the larger actually weighs 8 pounds less because it uses lighter cylinders. All engines are completely rebuilt from very high quality parts before flight. They are not just removed from cars. The parts we use are specifically selected to convert the engine for the rigors of flight use. Forged pistons, Inconel valves, chrome rings, ARP rod bolts and many other components are upgraded in the rebuild.

To absorb the propeller and flight loads a “5th bearing” is added. It is a billet housing with a very large bearing from a V-8, bolted on the end of the case.The ignition is redundant and utilizes two 40,000 volt systems, one driven by digital electronics the size of a match book, the other by a traditional set of points. The engine is direct drive, it has no complex reduction unit. It makes good thrust because it has more than twice the cubic inches of a Rotax 912. All of the systems on the engine are intentionally patterned after those on Lycomings and Continentals, because they are the  model of success in proven aircraft power plants. People who do not acknowledge certified engines as excellent models of success are often just zealots.  To succeed in experimental aviation you need dispassionate information not emotional opinion.

One of the unique features of the Corvair is that it can be built at home, from our information and parts and a locally acquired rebuildable engine, or it can be purchased from us, test run with logs. 90% of current builders are building their own engine at home. Only 10% of the builders opt to have us build their engine. We have happy to serve both builders. In either case, Corvairs are the best match for builders who want to understand and be the master of their engine.

Because of the plans built vs production engine nature of the Corvair, there are large variations in how much builders budgets run. Below is a quick look at the differences. Keep in mind, these budgets are for first class, completely overhauled, zero timed engines with 5th bearings, starting, ignition and charging systems. We have clever builders who have built and flown engines for less than $3,000, but this not representative of main line builders. The numbers below are much better for Zenith builders to budget on.


2,700cc / 100HP typical homebuilders budget: $6,500- Same engine assembled and run from us $9,750

2,850cc / 110HP typical homebuilders budget: $7,500- Same engine assembled and run from us $10,750

3,000cc / 120HP typical homebuilders budget: $8,500- Same engine assembled and run from us $11,750


If you are attracted to the concept of building your own engine, but have not built motors before, Good.  About half of our builders have never built any kind of an engine before. Our main work is teaching people what we know and providing the parts to work with. Our system does not require anyone to be a machinist nor to have previous engine experience.

The procedure of building an engine in your shop follows this format:

1) Get a conversion manual and DVD’s from us, use them to find a rebuild able core engine locally. Disassemble this engine following the steps in the DVD.

2) Send the crank and heads to our approved facilities for rebuilding and modification. They come back ready to ‘bolt on.’ Other parts of the engine are cleaned and inspected. The parts to convert the engine are ordered from us, many of the standard rebuild parts like lifters and gaskets are available from local auto parts stores. We do not ‘middle man’ anything you can directly buy.

3) Assemble these parts according to the manual and DVDs. There is no machine work required, only basic tools are needed, and a few specialty tools like a torque wrench. Many builders attend our free Corvair Colleges and directly learn hands on skills. You can even bring your parts and assemble them under our supervision, and test run your engine on our equipment. College attendance is a plus, but not required. Our methods work without direct training; a good number of engines are built and flown each year by builders who have never met me in person.

4) The test run serves several purposes. We teach people to build one of  three specific models, and we teach them to use specific parts. Not only are these proven, but it also allows me to verify from a remote location that the engine was assembled correctly. A builder can report his static rpm, CHT, oil temp during the test run with his Warp Drive prop at the specified setting, and I can confirm the output and assembly of the engine without seeing it personally.

If you would like a sample of the information on working your way through the above four steps, get a look at this: Getting Started in 2013, part #1, Crankshaft process options.

I have broken down building a Corvair and installing it on your airframe into 42 “groups”. The previous link is about  ‘Group 1000’ the crankshaft. If you would like to look at every part that goes into a Corvair, along with the conversion parts we sell, look at Groups 1000 -3300 at this link to our catalog: http://www.flycorvair.com/products.html

All builders get started with a conversion manual. The first part of the above link is about manuals and DVD’s.  The direct link to the manual is: http://www.flycorvair.com/manual.html. almost all builders looking for a rebuild able engine also order the Disassembly  DVD, which covers core engine selection visually. The direct link to it is: http://www.flycorvair.com/videov.html We encourage everyone to get started with information, even if you are pretty sure you would like to purchase a production engine from us. If you eventually buy an engine from us, we directly reduce the price to rebate all the money you spent on manuals and DVD’s.



Links to related stories:

a) – Corvair Weight story: Corvair vs O-200…. weight comparison

b) –  Samples of our production engines:  2012 Corvair Engines For Sale: 100, 110 and 120 HP

c) – For an explanation of ‘flat rating’ and a Zenith engine build : Shop perspective: Mastery or ?

d) – A story about engines running on our hangar Dyno: http://www.flycorvair.com/thrust.html

e) Engine of builder now working on Zenith airframe: World’s Strongest 3,000cc Corvair, built by Greg Crouchley

f)  2.700cc engine we built for Becky Shipman’s 650: Shipman Engine at CC#22

g) A story about the evolution on 120HP Corvairs: 3,000 vs 3,100 cc Corvair engines.


In the photo above, the 701 mount appears slightly distorted by the camera angle; it actually has no down thrust in it.


3) – 701/Corvair installation components


The two parts that are unique to the 701 installation are the mount and the exhaust system. Other than this, the parts are common to our Zenith 750 installation.  We are glad to make the mount and the exhaust on a special order basis. The pricing on these items are the same as the equivalent 750 parts. For all of the other parts, refer to our “Zenith 750 reference page” or our regular catalog of parts.



4) – Photo essay of our development work on the 701, 2006-2010.


Below are a sequential chain of photos, mostly taken in our Edgewater Florida hanger that was our base from 2003-2007. All of these photos and their captions are on Flycorvair,com, our traditional website. They were in the “Hangar Update” monthly news section. I have put the original captions in Blue, and clarifying comments from today are in black.



Where we started: “The 701’s firewall rigidly mounted at a 17 degree angle on the build up stand, above. This is the beginning of developing the 701 firewall forward package.”



“In the above photo, Scott Thatcher’s 601 engine does jig duty in the construction of our CH701 motor mount. Like all other mounts, it began as a standard Tray. Long and careful study of the installation, and our experience with installing engines in airframes played into adjustments in the location as small as 3/16″. An engine hoist suspends most of the weight of the engine, and a scissor jack stabilizes the engine over the heavy duty shop table. The alignment was checked many times before the tubes were tacked in place. The mount and engine were then removed from the stand. The mount was finish welded on the bench with a Tig welder, using great care to minimize warpage. It was then reinstalled on the stand, and normalized with a gas torch. After cooling, I made a jig off the mount to capture its dimensions.

These are but a few of the steps in the long-term development of an engine installation that can be replicated by other homebuilders. Any one-off installation is comparatively easy. A good example is the Skycoupe. When working on its installation, I knew that there would probably never be another one. Thus, no jigs or tools were made, nor consideration given to the multitude of factors that would make the path easier for others who would follow the installation. It only had to serve well on one plane. Conversely, the Corvair/701 installation may prove to be popular. Our experience pays off here and will later allow rapid development of a highly refined installation pending positive flight testing.”



In 2006, Grace and I bought our house on an airstrip 90 miles north of Edgewater. I commuted back to the old hangar for 14 months to finish projects there and because I gave my word to our friend who I leased the hangar from that I would do 4 full years there. The hangar was $2,200 a month and it was a long drive, but I was determined to live up to it. ” Above is a photo of the actual 701 flight engine sitting on the mount. This project is continuing at the main hangar in Edgewater. Work progresses on it between regular orders.”




“Above is a photo of the 701 airframe in the main Edgewater hangar. This illustrates how we tackle complete airplane projects in 2007. The 701 is being built as an E-LSA, which allows it to be built 100 percent for hire, unlike amateur builts, which must meet the 51% rule. The owner separately contracted us to build the firewall forward package for his airplane. Gus Warren of Fly With Gus separately contracted to build the whole airframe.”



“You can see above how close the Corvair’s center of gravity can be brought to the firewall. Geometry of this mount was carefully worked out to allow the use of our Intake Manifold and a Niagara cooler. When W&B and flight testing data comes back, we’ll have more information. The key to a successful 701 installation is not simply how much the engine weighs, but how close you can bring the engine to the CG.”



We later switched the plane to having the oil fill in the Valve cover like all our other installations. “Above is a top view of our 701 engine installation. It is also being fitted with the new Oil System. No oil components on the firewall make the 701 installation much easier with its very limited firewall space. An oil filler neck is custom welded into the Top Cover of this engine. It is made from a 1″ aluminum tube, and has a Moroso O-ringed aluminum cap welded into it. This was done for potential cowling clearance when we were thinking of a super narrow custom 701 cowl. At this point, we’re steering toward a 601 style cowl on the 701. We want to get this one flying and gather flight test data. We’re trying to keep as many of the parts for the 701 installation common to the 601 to avoid a long development. We’ll have more commentary on this installation when it’s done and flying.”




“This is a view of the lower portion of the 701 installation. Although I had my doubts, Kevin found a way to rotate and trim our CNC bent stainless pipes for 601s into a slightly different configuration that neatly fits into the 701’s mount. This engine will be equipped with an Aero-Carb.” Engine was later switched to an Elison EFS-3A that worked a lot better.



“Above is a photo I shot in Edgewater last week. The airplane is more finished than the photo depicts. The leading edge slats and flight controls, not seen in the photo, are complete and have been mounted. The glass is out of the plane to facilitate the detail work. One builder wrote to ask if it would take a long time to develop installation components after the combination is tested. The engine uses a lot of parts from our existing catalog. The Nosebowl is the same one we use on 601s. The sheet metal to mate it to the 701’s airframe will be different, something reminiscent of a Thorp T-18. All the engine parts, including the Baffling, oil cooler and oil system, Starter, Gold Hub and alternator are our standard parts. The exhaust system is made from 601 Exhaust pieces in a slightly different orientation. The only truly unique pieces are the motor mount and lower intake manifold. Even the prop and spinner bulkhead arrangement is the same as the 601.”



“Above is a good look at the detail quality of the 701 engine installation. Over the years, our installations have gotten cleaner and cleaner through Manuals, Colleges, Forums, and this Web site as well as http://www.ZenVair.com. We’ve shared this information with builders everywhere. It not only looks clean, it’s technically correct and flight proven in every way. The 701’s installation differs from a 601 in only minor details. The oil filler is welded into the Top Cover, the Intake Manifold is segmented for installation. But by and large, it utilizes nearly all our flight proven parts, which will yield smooth flight testing and easy replication by builders everywhere. This installation has a 2002 Niagara cooler, the Gold Oil System and our standard Baffle Kit. The large sending unit is for oil pressure instrumentation in the glass panel, below.”




“N9569S has a completely stock 701 airframe which will allow apples to apples performance comparison. We have the airframe set up for a 66″ 2-blade Warp Drive prop with nickel leading edges. The thrust testing section of our Web site compares this prop’s performance against a Rotax 912S with an in-flight adjustable prop. It is hard core, direct comparison testing like this that gives me great confidence in this combination.”



“Sitting on the firewall above is the black box for the Stratomaster Enigma glass cockpit in the 701. This view shows how tight we have the Corvair to the firewall. Despite its proximity, there are no complex assembly or maintenance tasks like there would be trying to pull a mag off the back of an O-200 in this airframe. Having the aircraft within the forward CG limit is very important to achieving maximum performance from the 701 airframe.”

We later had a number of issues with the MGL instrumentation on this plane. MGL specified senders that were poor quality, and when the oil pressure sender partially failed I wasted a full day trying to track down the error, including pulling the engine complexly out of the airframe. The owner installed a MGL fuel Flow sender that was a plastic barbed fitting, something that no one should put in any flying fuel system.



“A look at the carburetor installation on the 701. The 35mm AeroCarb is spaced off the Intake Manifold by a 1” fabricated spacer which has flow straightening vanes in it. Gus worked out very clean and simple throttle and mixture cable installations. Whobiscat sleeps under the plane.



After I wrote the story below we found that the primary culprit in the running hot issues was that the owner had altered the ignition timing. This was my own fault for having more than one person in charge of flight testing, alterations and fine tuning. don’t repeat this mistake yourself. If people offer to help you with your plane, remember, no matter how qualified they are, you are still in charge. Above the cowl is tuff tested with yarn to check airflow at high angles of attack.


“Many of the things pertaining to the combination, like the weight and balance, are very good. But the aircraft owner disliked the Aero-Carb, so we replaced it with an Ellison. This change provided more issues than it resolved, initially. Second, the engine had adequate cooling in February, but as Spring grew much warmer, we needed to rework the cowling. The Ellison’s sensitivity to vapor lock compounded this need.”

“As an E-LSA, the aircraft had a short, five-hour test period. Although it was legally signed off, we weren’t kidding ourselves that the 10 hours we had on it constituted a fully tested power plant installation. While builders were understandably clamoring for details, we hadn’t put out much information or anything up for sale. The day before Sun ‘N Fun, Gus took off from his hangar to fly the airplane over 100 miles to Sun ‘N Fun. Although the airplane had 25 flights on it, this was the warmest day on which it had flown. About 25 miles into the flight, Gus noticed the characteristic pinging of detonation and made the very wise decision to make a precautionary landing at a sod farm. The 701 airframe was designed to be operated in just such places, and the landing was a non-event.”

“Gus’ initial thought was to let the aircraft cool off, then fly back to the hangar. A courtesy phone call to the owner of the aircraft changed the plan and the aircraft returned to the hangar that same morning on a trailer. The story of the precautionary landing was carried on the Kit Planes magazine blog. Although it accurately and fairly reported the landing, many Internet aficionados colorized and expanded the story, including incorrect phrases like “engine failure.” I am careful with the things I write to be accurate. If I poked a hole in the radiator of a car and it overheated, I would refer to this as a cooling system issue, not an engine failure. It was mildly annoying to read the colorized reports and listen to amateur analysis from people who never saw the plane.”



“Our initial setup on the 701 used an Aero-Carb breathing air from directly inside of the cowling. This functioned fine, except the owner of the aircraft did not like the fact that he had to manually turn off the fuel with the mixture control whenever the engine was shut off. The owner is an aviator of enormous experience. He’s owned dozens of aircraft of all descriptions, including a Lockheed 12, Grumman Tracker, Sikorsky S-55 as well as a number of turbine powered aircraft. He holds an A&P, IA, and most of the other ratings the FAA offers. Although the Aero-Carb and Ellison are both flat-slide carbs, they function completely differently. The Aerocarb was immune to under cowl temps because it has no diaphragm and stores very little fuel inside it. The Ellison, because its throat is larger, provided an immediate seat-of-the-pants difference in power output, but as the weather warmed up, it showed itself to be temperature sensitive. We put a blast tube on its diaphragm, and ceramic coated the exhaust to lower the under-the-cowl temp. Yet we resisted making a specialized airbox because the goal was to keep the installation as simple as possible so budget builders could follow it at home.”

“The continuous warm air introduction turned out to be a mistake. I feel it was a major contributor to a warm engine beginning to detonate. At power, the carb inhales 150 cubic feet of air per minute. If this comes from the outside, it has significant cooling effect on the carb body. If it’s warm air induction, that large quantity of air raises the carb temp by 80 or more degrees F. The external blast tube on the diaphragm will not overcome the volume of air going through the carb. The above photo shows the 701 system as it is flying now. The air filter is in the aluminum canister, and it primarily breathes cool air from the lower part of the Nosebowl. The feed hoses are 2.5 inch.”



“The tuft tests of the cowl revealed it had low flow characteristics on the exits. A check of our Web site will show that many years ago, we put radiused lips on the bottom of the 601 firewall to improve cooling. Although it was not initially necessary in cool weather, we’ve since installed them on the bottom of the 701 firewall, and, more significantly, on the sides of the firewall where most of the air exits. These radiuses work in conjunction with the fixed flaps we installed on the cowl. Tuft tests and flight data showed that this made a tremendous improvement.”



The 701 has a very narrow firewall compared to the 601/650 and 750. I initially thought that we would use a ‘gill’ shape like a T-18 or a Pitts to exit to cooling air. Tuff tests revealed that the shape of the wind shield and the proximity of it to the cowl side exits hurt this. On the 601/650 and 750, we use a traditional hot air exit of just the bottom of the cowl, and it has always worked right off the bat.

“The tuft tests also showed a significant amount of reverse flow where air actually entered the rear of the cowl and flowed forward. There’s a number of very successful aircraft that use the cowling style with gill exits like our 701 Cowl; notable is the Thorp T-18, which has been flying in great numbers for half of the powered flight era. But eyeball aerodynamics and basic comparisons don’t take the place of flight testing. The 701’s more vertical windshield much closer to the cowling makes a high pressure zone at the base of the windshield. The small crescent shaped rib attached to the upper part of the firewall in the photo acts as a dam to prevent this reversed flow. There is one on each side. Gus hand made them in an hour or so.”



“The top view, as compared to earlier photos shows that the Top Cover, which had an oil fill welded into it, has been replaced by a Gold Top Cover. The oil fill is in the valve cover, just like all our other installations. This eliminated the need for an oil fill door in the top of the cowl. The oil cooler in the photo is a Niagara 2003. The plane flew its first 5 hours on a 2002 cooler, like the rest of our high performance cooler installations. Our 3100cc 601 installation flew several hundred hours on a 2003 cooler and it out-performs any other cooler flying by a long shot. It’s overkill on most installations. But in March, we opted to upgrade the 701 to this cooler also. This was an easy change because our Baffle Kits are designed to accommodate either cooler. This was part of the refinements to the 701 installation that were ongoing before Sun ‘N Fun.”



“Above is a view of how tight the Corvair fits in the 701. The wires in the photo are part of all the test leads to evaluate temperatures on the engine. The plane has a very elaborate MGL set up with flight data recording. This allows us to download and replay any part of the flight. The two black tubes in the photo are part of the Motor Mount. These attach to the steel tubing behind the windshield. They have to be there no matter which engine a builder chooses. The Corvair balancer is only 6″ in diameter, and snugly fits between the tubes with 1/2″ to spare on each side. With the engine in this position, the plane is in the weight and balance envelope of the designer, without any ballast. Planes flown forward of the front limit will have poor slow speed performance, and be prone to damaging the nose gear on landing. Engines moved forward would thus require ballast, something no well designed package has.”

“Two people have told me they were planning on using a rear starter on their Corvair powered 701. When looking at these photos, it is easy to see that anyone planning on this hasn’t examined very closely the installation, or has not finished the plane. Gravity, math, numbers and our flying 701 trumps other peoples’ guesses at what the weight and balance will look like. Twenty years ago there were things I wanted to do in homebuilding that time showed were poor ideas. How I got to where I am today is by letting my allegiance be only to what flight testing has shown to work. Pet theories and predjudices rarely add up to a lot of hours flown. This is also a good photo of how the inherently compact Gold Oil System fits in the 701 installation.”

“The top view of the engine shows the compact and organized installation, featuring The Gold Systems and Our Baffle Kit. The great majority of Corvair powered 601s are being finished by their builders in their home workshops, not at our professional facilities. The point is that our systems are flight proven in numerous installations and have been highly refined to be easily installed and trouble free, even when put together by first-time builders.”



“The above photo shows the 45 degree fixed cowl flap on the underside of the 701 Cowl. In addition to this, there is now room for exit air on the underside of the firewall. It is important to note that the several hundred man hours of testing and research that have gone into perfecting the 701 installation were done by myself, Gus and Kevin at no expense to the aircraft owner. The owners experience meant that he was not a regular homebuilder in search of a proven product. He was excited about the idea of being a facilitator and a pioneer of the Hangar Gang’s efforts. He was well aware that new systems are not brought out without teething problems. However, we had a clear understanding that the R&D would be done at our own expense.”

“There are many cases in sport aviation where people who didn’t know what they were doing tried to charge an aircraft owner for the expenses of their learning curves. As professionals, this is out of the question for us. We will gain back our investment by selling high quality parts to facilitate the installation. “

“With the modifications shown above, the aircraft is now a reliable, hot weather, turnkey performer.  Gus flew the airplane several times in one day after the modifications were finished and pronounced the installation completed. It was a long haul to get to this point. People who’ve read my writing know that I’m an advocate of rigorous testing. All too often, things that have flown on a single airplane a few trips around the pattern are labeled “Flight Tested;” our 701 project would have met this standard 10 minutes into its first flight months ago. Had we sold anything based on its initial configuration, or had we been working with a customer who felt he was buying a proven product, great disappointment certainly would have awaited. Even with our extensive, decades-long experience, it takes time to make stuff trouble free.”



“Gus holds open the cowl of the 701 to show off the FlyCorvair.com engine installation.
In order to serve the most builders and get the best use out of all of our fully flight tested products, the 701’s engine installation is very close to a 601’s. The engine itself is identical. This 701 sports a Gold Prop Hub, Gold Oil System, Niagara Cooler and an Electronic/Points Ignition System. It also shares in common with the 601 the Baffle Kit, Corvair Nosebowl, 2- blade 66″ Warp Drive propeller, and most of the Exhaust System.”



“Blast from the Past: Steve Upson Alive. During the final phase of 701 modifications and testing, original Hangar Gang member Steve Upson, above, spent the largest chunk of time at the Edgewater hangar that he has in several years. People who met Steve several years ago knew him to be an incredibly talented aircraft mechanic as well as a chain smoker and connoisseur of quantity over quality beer. This caught up with Steve several years ago when he had emergency heart surgery and an abrupt lifestyle change. Today Steve’s alive and well.”




5) – Builders working on the combination


We have a number of pictures in the archives of builder’s 701/Corvair projects. I am going to extract them and put them on this page as running updates. To get started, Let me share a photo of one of the best known builders working on the combination: Terry Samsa of MN.


From Corvair College #20 in MI: Terry Samsa running his 2,700 cc Weseman bearing power plant on our test stand. Terry drove in from Minnesota, a 14 hour drive. At this moment, you can be assured that he thought it was well worth the trip.



6) – Notes on poor products to avoid


The 601/650 and the 750 reference pages both have a ‘Section 9’, sharing comments on parts and companies that no one should ever buy aircraft parts from. If you are even considering, for a moment, buying any Corvair part that I didn’t make, you need to read these sections carefully to know what you are getting into. Also, be aware that many of the things advertised on Barnstormers and E-bay Motors as “Built by William Wynne” have nothing to do with my work.


Simple example: Look at the last photo on the 750 reference page of the destroyed plane. notice the broken motor mount. That was caused by the original installation’s rear starter requiring bent tubes in the mount to clear it. The people that made it didn’t ever take classes in Structures and Materials, nor did they teach Welding at Embry-Riddle. I did these things, and I know why that mount broke. You don’t need this type of education to build a plane, but morally, you need to know what you are doing before selling aircraft parts. None of the people who ran now bankrupt LLC’s meet this simple requirement.


In the age of the internet, people comments last a long time and are also easy to fake. If you look around, you can find comments from alleged builders offering testimonials for all products, even ones from now bankrupt companies. Look at the dates, and ask if these people are even still building today. Very few of these comments come from experienced builders, and many other the people would have long retracted the comments in light of what they were stuck with. Only 25% of home builts get finished. The percentage that get done with products of bankrupt companies has to be a tiny fraction of this. If you want to win at this game, it starts with making good decisions about who you are going to work with.


I am clearly going to state again, If you have parts from another company, one I consider to have been run by vermin, I will not knowingly provide you any advice, service nor sell you any part to ‘upgrade’ your motor, nor will I allow you to participate in our ‘Zenvair’ discussion group, or attend any Corvair College.  It isn’t out of spite, it is simply because choices in aviation have consequences, and if you choose to work with vermin or their products, you are going to live or die with that decision. You can’t ‘upgrade’ junk by bolting good parts on it. Band aids don’t fix diseased things, amputations do. Zenith does not offer advice not service to people who bought Savanna kits, and this is the same principle.

I could list every name of every LLC that was in business to cash in on Corvair builders dreams and plans, but it would do no good. Just this week I heard of a new one starting again, right from the same address where the last one left off. Let it suffice to say that if anything on your plane came from Valdosta GA, I genuinely wish you good luck, your going to need it.

It is a free world, and no one has to listen to my experience nor advice. If you don’t like my tone, what I look like, things I say or perspectives, you are free to use these as a reason to discount or ignore what I have to say. A long time ago I learned in aviation that I needed to listen to the perspective of anyone with experience they wanted to share, even if they were not someone I personally liked.  I have learned much of what I know from people I would not have cared to be friends with. Aviation has serious consequences, and it is foolish to just restrict yourself to learning from people you ‘like’ or find ‘pleasant.’

Corvair – Pietenpol Reference page


Here is a collection of information we have put out for Pietenpol builders. I have swept it into this single page so builders can have a single reference point on the airframe. As we have more content, I can easily add a link here and keep this current. This page is just a brief set of notes and links to stories I have written about Pietenpols. If you would like to start with a simple three page spec sheet on the engine, read this link first: Basic Corvair information

I can still recall the very first picture of a Pietenpol I ever saw, a grainy black and white image in Peter Bower’s “The 25 most practical Homebuilts.” It was love at first sight, I ordered a set of plans from Don Pietenpol the next week, and 25 years later, the design and the people who love them still hold a place in my heart.


 Above, A great afternoon at Brodhead WI, 2009. R to L, the Piets of Gary and Shad Bell , Kurt Shipman, Randy Bush, all Corvair powered.


Above, my proudest day in aviation. Grace and I with friends and my Pietenpol in front of the old Brodhead sign at the Pietenpol Reunion in 2000. We had just flown up  from Florida, and spent a great day with friends old and new, with my mother and father on hand. This single day made years of work in the hangar worthwhile.


(Click on any colored title to read the full story)


Pietenpol Aircampers:

Pietenpol review in pictures, 15 more Corvair powered Piets

Bob Lester’s Corvair/ Pietenpol nears 800 hours.

The Bell Pietenpol, 3 generations of flyers

House Call on Pat Green’s 1,000 Hour Pietenpol

Pietenpol Power: 100 hp Corvair vs 65 hp Lycoming

Steve Williamson Pietenpol at 60 hrs., SoCal.

New Pietenpol, EAA #1279, French Valley CA

New Pietenpol #3, Mike Groah, Tulare, California

New Pietenpol, Gary Boothe, Cool, Calif.

Gary Boothe’s Pietenpol, flying video

New Pietenpol, 2700 Corvair, Don Harper SC

Randy Bush’s Pietenpol hits 500 hours.

Farewell to a Good Man; Robert Caldwell departs.

Guest Writer: Pietenpol builder/flyer Kevin Purtee

Knoll Family Pietenpol

Bob Dewenter’s Pietenpol project

Pietenpol Project – Terry Hand

Pietenpol 2,775 cc Corvair; Trevor Rushton from UK


Oshkosh 2004,  Alex Sloan, holding plaque has just been presented The Tony Bingelis Award.  L ot R, Noted Pietenpol builder and pilot Mike Cuy, Pietenpol historian and newsletter editor par excellence, Doc Mosher, Grace and Myself. I have always tried to give something back to todays Piet builders, as I personally benefitted from the efforts of the builders who preceded me. I have worked with Doc on this, including developing the Weight and Balance testing and data bank. He and his wife Dee have been the single biggest factor in the design’s explosive popularity in the last 10 years.


Above, Speaking at the Brodhead forums, 2008. This gathering in July is my favorite event of the year. It is a great place to socialize, meet new friends, see planes and exchange ideas. I have only missed one year in the last 19, given forums the last 12 years. We also do practical stuff: we weighed 28 Piets on electronic scales there in a two year period. The data is in the back issues on the newsletter, available at Pietenpols.org.


Installations and airframe parts.

Pietenpol Mount on airframe

Pietenpol Weight and Balance project

Pietenpol Weight and Balance article source

Current Corvair Installation in a Pietenpol, part #1

Current Corvair Installation in a Pietenpol, Part 2

Steel tube Pietenpol fuselage with landing gear and 12 x 4.8″ tires.

Great lies from discussion groups…….part #1

Pietenpol Products, Motor mounts, Gear and Instalation Components.

New die spring landing gear on a Pietenpol, 10 a.m.-4 p.m.

Pietenpol Motor Mounts, P/N 4201(C)

Pietenpol Fuel lines and Cabanes

Fuel lines and Cabanes, part 2

Pietenpol Box Spar Construction, 6/27/13

Cooling with J-3 style cowls. (Pietenpols, Cubs, Biplanes, etc)

Three Pietenpol Motor Mounts

In Search Of … The Economical Carburetor

Franklin Engine Runs at CC ##22 KGTU Spring Break 2012


Terry Hand’s 2700 cc Pietenpol engine – w/Weseman 5th bearing

 “Zen-vair” and “Piet-vair” Discussion Groups, your resource..

Pietenpol lift struts; $65, a free education, and fun with friends..

Custom Pietenpol engine mount.

Yes, Pietenpols do need 5th Bearings..

Evolution of a Pietenpol

Evolution of a Pietenpol pt. 2

Andrew Pietenpol, aviator and Grandson of BHP, right, attends Corvair College #4 with Grace and Myself in 2003. Greatest complement anyone has ever said to me in 25 years in aviation: Andrew told me that day “My Grandfather would have adopted you.”


Stories on the influence of BHP

B.H. Pietenpol, Patron Saint of Homebuilding

Don Pietenpol Passes, 1/8/14

Vi Kapler passes from this Earth, age 88.

New Pietenpol Family website

The Cherry Grove Trophy

Help Needed, Wikipedia error on Pietenpols

Cherry Grove story, “The long way home”

Cherry Grove story, Part 2.

Pietenpol first flight; Honolulu International.

Flathead Ford, 71 cid. Freedom to pursue happiness.

Guest Editorial, Pietenpol builder Terry Hand.

Bob Lester’s 48 flight hour, 3400 mile Pietenpol adventure

Pietenpol Builders and Pilots at Corvair College #31.

Ralph Carlson and Conversion Manual #1.




Above, Kevin Purtee and I speaking at Corvair College #32. Although we look very different, we have a lot of things in Common: We are both the same age; We are both Embry-Riddle graduates from the same Degree Program; we have both worked in aviation every day since we were 26; we have very similar perspectives on risk management.  Read: Thought for the Day: Two paths in managing risk.


If you would like to read a number of personal stories, some with very harsh lessons on the unforgiving nature of flight, Please look here: Risk Management reference page. If you read them with an open mind, some of my friends will be able to posthumously teach you to take care of yourself. -ww.


Fuel Injection – Corvair flight engines reference page


Here is one spot where we have collected a number of different stories on Fuel injection for Corvair aircraft onto a single reference page. Like the other reference pages, it is a central starting point on the topic, and easy to keep updated or make additions to. If you are interested in learning more about this topic, read on, there is a significant amount of information here.

If I were to pick a single topic that new builders are interested in, but know little about the applications of, It would be Fuel Injection. This is a topic dominated by misconceptions and myths. Here is a quick check: Do you think that a port fuel injection engine or one with a carb on a long intake manifold makes more power? Would you be surprised to learn that the evaporative cooling effect of the carbs fuel delivery can give it a significant advantage? It does, and to learn this and many other points on reliability, read on. Unlike much of the info on the net from armchair experts, the information below is straight from experience and testing…in aviation settings, not in cars.




The information below is in the following order:


1) Links to stories I have written on FlyCorvair,net

2) A full print of my Group numbering system #3700 EFI notes.

3) A reality check story from 2008 on EFI failures

4) Notes on Internet ‘experts’ you should beware of

5) A 385 mph EFI plane and some final thoughts.


Above, a rear view of the Panther engine. Mounted on the intake is a Precision Mechanical fuel injection system. Initially, these was the planned fuel system for the Panther, but after careful evaluation, Dan Weseman opted to go with a very simple MA3-SPA carb. All of the aerobatic flights on video on the Panther site are done with a one barrel aircraft carb, not injection.




1) Links to stories I have written on FlyCorvair.net:


Click on the titles in color to read the full stories:


Mechanical Fuel Injection Testing

Compares Precision and Airflow performance instalations

Fuel Injected Corvairs

stories on 3 running EFI engines

Group Sources for the new numbering system.

Covers that EFI is Group  #3700 and Mechanical injection is Group #3800.

Panther Prototype Engine 3,000 cc/120 hp to OSH

Another look at the Precision system

Corvair Powered Davis DA-2, w/EFI

The only successful flying EFI Corvair powered plane. A hard won achievement.




2) A full print of my Group numbering system #3700 EFI notes:


3700- EFI (Electronic Fuel Injection)


Many people just arriving in aviation are interested in electronic fuel injection.  Some homebuilders are impressed with its performance in cars or have read about one of the handful of experimental aircraft flying with fuel injection. After listening closely to builders, I discerned their interest originated from five reasons: 1) They thought it would make the engine more powerful; 2) They thought it would reduce fuel consumption; 3) They felt that it would eliminate the possibility of carb ice and eliminate the need for carb heat; 4) They thought it would be more reliable than a carb, or; 5) They just wanted to try it. Experience has shown me that the first four are not true to any meaningful degree, and that #5 is the only reason that makes sense. If you are pursuing EFI for reasons #1-4, you are going to be disappointed, but if #5 is your motivation, then the project may be a success to you.

Let me first say that I am not against EFI, but I think that builders should know the facts before they pursue it. My background on EFI installations in planes is better than most. A guy who works on them all the time in cars, but doesn’t put them in planes, has a long way to go before he learns what he needs to know to be reliably and safely flying. I did a lot of work on Jim Rahm’s 427 cid V-8 Lancair IVP. It had the best EFI system in the air. We had the best people working on it, a nearly unlimited budget and experience that no homebuilder in his garage could match. It took a lot of very hard work to make it the reliable system. Just because Jim’s motor made 600 HP and you only want 120 HP doesn’t mean that solving the installation issues will only cost you 1/5 the time and money. And even if it did, we would still be speaking of time by the calendar years and money by the cubic foot. When I read discussions on the Net about EFI on experimental aircraft, I can quickly tell who has never assembled and flown a system.  95% of the advice on the Net is offered by people without flight experience. Out of the 30,000 experimental aircraft in the U.S., I am fairly sure that less than 300 of them have EFI. I cannot think of a single significant aviation record below 500 HP that is held by an EFI engine. There have been many clever people who put a lot of effort into EFI on planes, with little result. No matter what caliber of auto mechanic you are, experience says that you will find exceeding the performance of carbs or mechanical injectors very difficult, and EFI may never have the reliability record of the simple 1 barrel carb.

Out of the roughly 300 experimentals flying with EFI, the vast majority of them are using 1990s auto engines with EFI from the factory. In this case, the factory engineers did most of the work. If you think about it, there are very few motors like O-200s, VWs and Corvairs flying on EFI. And the ones flying can’t boast the flight record of carbureted engines. I have seen a number of these planes flying with 35psi fuel pumps inside the cockpit with barbed hose connections and hose clamps. No one should dream of flying things like this. Let’s examine the points one by one objectively to learn about the issues and make an informed decision.

1) I have seen claims that EFI makes the same engine 30% more powerful. Nothing of the sort is true.  Engines make power because they burn a mass of air mixed with the right amount of fuel. There is no way that an engine is going to inhale significantly more air because it doesn’t have a venturi carb. This advantage is slight, and would be well below 5% on an engine like a Corvair. To see any more difference than this, the cylinder heads and intake tract would need to be designed for it right from the start, by very smart people with a lot of sophisticated equipment (of the caliber found in Detroit factories). Slapping an EFI system on the Corvair will not have the same effect. Fuel injected motors are said to make slightly more power because the fuel is better atomized. But carbs, even simple ones, are surprisingly good at this. The amount of records still held in racing by carbs should tell anyone that the EFI power advantage is minimal. Carbs have a very serious advantage of vaporizing the fuel well upstream, and having the air/fuel mixture cooled and its density increased. In almost every case, this offsets any gain in power from atomized fuel. When running at power, Corvair intake manifolds are cold to the touch from vaporizing fuel. EFI does not have this effect.

2) EFI will not significantly reduce fuel burn in a Corvair engine. For best economy, engines need to run a lean mixture. EFI has the theoretical ability to atomize fuel slightly better allowing it to run slightly leaner mixtures than a carb could without detonating. In actual use, it is foolish to run an engine this close to detonation. Modern auto engines can do this because they have computer-controlled ignition tied to a knock sensor and the fuel injection. Without these devices, any significant fuel burn advantage is lost. Many of the well known auto power proponents, even those who work with computer controlled EFI engines, clearly state that EFI doesn’t significantly reduce fuel burn for a given HP in aircraft engines. The efficiency advantage in cars is gained by running in “closed loop” with air/fuel ratios near 14:1. Under this operation, the injectors are fine tuned by reading the O2 sensors many times a second. The reality that few new builders understand is that any engine running at 75% or more power has to be running an air fuel ratio of 12:1. At this setting, O2 sensors don’t reliably work, and the system will operate in open loop, forfeiting any efficiency gains while retaining all the complexity and vulnerability. I have never seen any EFI flight engine that will fly at cruise power in closed loop mode. They are all just operating off a set of pre-programmed values based on RPM and MAP. These can be very crude, as some aftermarket EFI systems have RPM increments as rough as 250 RPM. In cars this would be masked by the O2 sensor moderating the injectors, but it can’t when it is in open loop. It is technical reasons like this that allow carbs to often demonstrate smoother operation than EFI in experimental aircraft.

3) EFI is less prone to carb ice, but is not immune to this trouble. There are still conditions that can cause this trouble. Almost all injected engines have an alternate air source. Homebuilt aircraft in Canada are required to have heated alternate air no matter what the fuel system is, and there is good logic to this. For a more complete discussion of this, see the article on carb ice at the end of the Manual.

4) Many people feel that EFI will free them from things like carb ice, reducing their level of risk in flight. While the risk of carb ice would be reduced for a pilot too careless to use carb heat, many new risks are introduced. EFI requires high pressure pumps, regulators and lines; it can be stopped by a piece of trash in the fuel that a carb would easily pass; its numerous electrical connections are prone to failure by corrosion or poor crimping; and the whole thing is so electrically dependant that most people fly with two batteries. Contrast this with a gravity feed fuel system in a plane with distributor ignition which will run for hours on a small battery with no input from an alternator. You cannot focus on the one possible advantage of a system without considering all the downsides that come with it. Automotive EFI installations are reliable today because auto makers spent literally billions to make them so. Brilliant people in Detroit who are specialists in dozens of details of the installations and privy to incredibly accurate statistical data on failures allow them a great corporate body of experience to tap into with every installation. It is my feeling that anyone looking into EFI who states that it is more reliable is making an argument for the car, not what an individual homebuilder can do in a plane, where a single detail of installation may compromise the system.

My observations on reliability are simple: Any system that uses lower pressure fuel is less likely to leak. Gravity is better than 5 PSI, and 5 PSI is better than 40 ; any system that uses no electricity is better than one that uses  a little, and one that uses a little is better than one that uses a  lot, especially if the one that uses a lot needs it to be a  certain voltage; any system that has less parts and connections is less likely to  fail,; digital electronic connections, working a low voltages, are very sensitive  to corrosion, temperature, and vibration, things planes produce more than newer  cars.

5) Being an experimenter at heart and wanting to address the challenges of an EFI installation is a valid reason for trying it. You know a good, reliable and airworthy system is quite a challenge because you don’t see them often. Anyone who achieved this could be justifiably proud of his creation and would learn a lot along the way. A person who is motivated by this will be satisfied when it works, whereas people motivated by #1 – #4 are bound to be disappointed when EFI cannot live up to the overblown claims many armchair/Internet experts make for it. The only good reason to work on an EFI Corvair is because you want a challenge, and this is more important than finishing your plane soon, or operating at a lower risk level. This is a valid position, and I support anyone who knowingly makes it.




3) A reality check story from 2008 on EFI failures:


” A Christmas story”

 At 8 a.m. on December 24th 2008, I was driving my 175,000 mile EFI S-10 up I-95 at 75mph. I had promised my parents that I would make it to their house for Christmas Eve dinner. I had never had a bit of trouble with this EFI engine. Near Richmond, Va., it quickly died out, and I was only able to coax it into a truck stop at 10% power. A morning of diagnosis showed that the pressure regulator had died. It was not in an easy place to get to, no one had a replacement and the truck was worth maybe $500 before it was broken. I gave the truck to a 20-year-old tow truck driver wearing a Chevy hat and a Jack Daniels sweatshirt, as a trade for a ride to a car rental place. We got there 10 minutes before they closed. The driver asked me several times if I was really giving him the truck and if I really was from New Jersey. The experience was counter to many things he had been told about people from N.J.  After some reservation, he took the gift of a truck from a Yankee on the eve of the birth of Jesus to have special significance.

 Such a warning less failure in a plane might prove to be lethal. Note that aircraft carbs almost always run even when they are having an issue.  A good look inside Pat Panzera’s Contact! magazine issue #96 shows a destroyed homebuilt aircraft, product of a sudden EFI failure. Here is a story of a guy who may have felt that carbs and engines without O2 sensors were stone age. Maybe, but stone age tools are noted for reliability. I am glad the builder was not more seriously hurt. Over the years, a number of people have written to explain that they are going to engineer their own EFI systems, or use something called “shareware” to program one (the blind leading the blind on the Net). Out of perhaps 50 people who have written this, not a single one of them went on to produce a running EFI engine. Experience tells me that people who arrive with a big flourish and little consideration for what has been accomplished have a very low chance of flying anything.




4) Notes on Internet ‘experts’ you should beware of:


A modest search on the internet will reveal many people speaking about EFI for Corvair powered planes. Armed with the information I have printed above, you can debunk most of the claims people make. Still, there are people who present a case to new builders as if they are some type of experienced expert to be followed.

The internet is an odd storage device. I holds more old trash better than any landfill on earth, and it keeps it fresh, even long after the project was abandoned. Let me share by example: Don’t waste the time to look it up, but there is a long detailed website run by “Haynes Engineering.” Sounds official, but it was just one guy in a barn who had never built a flying plane before, offering a long how to session on putting EFI on a Corvair in a Zenith 601. I never met the guy, but I did email him several times, and he spent a long time on Mark Langford’s discussion list, where he had many fans who eagerly awaited Mr Haynes demonstrating all the things he promised from is Harley Davidson salvaged system. Although I offered to publicly test run his engine at a college, Mr. Haynes soon despised me, probably for not recognizing his brilliance. His website is all about putting a Corvair on a 601, but makes no mention of Our success with doing this, or my work at all.

If you have built planes, it was easy to see that Haynes didn’t know much about planes, but had the kind of ego that didn’t like admitting that. He was a foolish cheap skate, ‘rebuilding’ his engine with a used cam and worn gear, and using angle iron to build a motor mount. His EFI system had hard aluminum lines where it needed flex ones, and he spent a lot of time trying to use a little outboard starter. In the end, after getting many green guys excited, he couldn’t make the engine run, and instead started it for 5 seconds on starter fluid, and then wrote a post to the internet silmaltainiously declaring victory and quitting airplane building altogether. Does this sound like a stable person who you can learn from? Is it the kind of information that you want to bet your life on? This was years ago, yet I saw the website just last week, with no mention of the system never working or the whole aircraft project being abandoned.

If you are new to home building, the quicker you learn never to be distracted for real progress by day dreamers and fools without experience, is the quicker that you will learn what really works, and how to incorporate these skills into your own experience and your own plane. The internet will provide an endless stream of people like that. 80% of the people who start a homebuilt do not finish. Be determined to be in the 20%. One of the things that the 20%ers all have in common is not getting sidetracked by fools.




5) A 385 mph EFI plane and some final thoughts:


I’m known for advocating simplicity in aircraft engines. This recommendation comes  from my experience on the opposite end of aircraft powerplants. Above,  Arnold Holmes (host of CC#17,#25, #29) and I stand behind the engine installation on a V-8 powered Lancair IV-P.  This is an EngineAir package that I helped develop from 1993 to ’98. It’s 450hp, geared,  injected, intercooled and turboed, and features air conditioning. Get a good look at the size of the 5-blade MT propeller.

  Eventually, about a dozen of these took to the air. They were stunning performers. I flew  from Oshkosh to Daytona Beach in three hours and five minutes in our first airplane, N420HP. This aircraft is on the cover of Sport Aviation in July ’97. If someone suggests I don’t understand EFI, ask them if they have flown in a 385 mph EFI plane they helped develop and build.

 The development of this engine took the work of many clever, dedicated people, and one  guy with cubic yards of money, Jim Rahm. It worked, but taught me that homebuilders at all levels  tremendously underestimate the effects of complication, primarily its delays and expenses.  Whenever I read discussions about electronic injection or computer controlled engines, I  can tell in an instant who has no practical experience with attempting to prepare these  systems for flight.

Evaluate your interest in fuel injection carefully. for most builders, it is a distraction, for some it will become a stumbling block, for a tiny number of people it may become a dangerously complex part of their plane, a part they thought would be the most reliable, but turned out to be the part they trust the least. This is pretty far from the goals that most people have when the first think about putting EFI in their plane.-ww