Basic Corvair Information

Here as a basic briefing on Corvair flight engines for builders getting a first look at using one.

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Above, A  3,000 cc Corvair flight engine. I built this particular one in 2012 for the SPA Panther aerobatic aircraft prototype.  The Corvair is a popular option on more than 20 different experimental airframes.

The Corvair is a General Motors designed engine, manufactured by Chevrolet.  1.8 million engines were built in the Tonawanda New York engine plant between 1960 and 1969. The Corvair has been flying on experimental aircraft since 1960, and I have been working with them as flight engines since 1989. It is a story of careful development and testing, a slow evolution to the engines we have today. It is ‘old and proven’ rather than ‘new and exciting.’

Configuration:  The engine is a horizontally opposed, air-cooled, six cylinder configuration. We only promote its use as a simple, direct drive power plant. The engine configuration is very similar to Lycomings and Continentals.

Displacement: The engine is effective without a gearbox or belt drive because it has a comparatively large displacement. Between myself and SPA, we have versions that are 2,700, 2,775,  2,850, 3,000 and 3,300 cc. The smallest of these has twice the displacement of a Rotax 912.

Power: Corvairs have several different power ratings. 100, 105, 110, 120 and 125+hp. These correspond to the five displacements listed above. They make their rated power at 3,150 rpm. They have wide power bands, making 75% power at 2,650 rpm. All engines will exceed their rated power at higher rpm, and they can be continuously run at full power at 3,400 rpm without damage.

Weight: The engine weighs 225-235 pounds ready to run. This is effectively the same as a Viking 130 and slightly less than a Continental O-200. It’s installed weight is 35 pounds more than a 912 Rotax, 25 pounds more than a Jabaru 3300. The Corvair is 40 pounds lighter than a Lycoming O-235. Larger Corvairs are slightly lighter because they have special cylinders made for them which make these engine lighter.

Reliability: From the factory, the Corvair made up to 180 HP in the car and turned more than 5,500 rpm. The engine is reliable and long-lasting because we are only operating at 60% of these levels. Conversion engines that run at the car’s red line rpm historically have short lives and cooling issues.

Cost: We sell complete engines from $12,750 to $17,750. However, 90% of our builders assemble their own engines working from our Conversion manual, DVDs, parts and support and a rebuildable core engine they pick up locally. Typically, they budget $8,500-10,500 to build a first class, zero timed, engine. Budget motors can be built for as little as $6,500.

Cooling: The Corvair has a factory cylinder head temp limit of 575F. This is the highest limit on any mass-produced air-cooled engine ever built. The engine as also the first mass-produced turbocharged car. GM engineered the motor to have excellent heat tolerance and heat dissipation. In aircraft the engine typically runs at 325 to 350 CHT.

Parts availability: Every wearing part in the engine has continuously been in production for 5 decades. The engine pictured above, only has an original pair of cases, and oil housing and cylinder head castings. All other parts in the engine, including the crankshaft, are brand new. Many of the parts in the engine, like the lifters and valve train, are common to Chevy v-8s. There is no part availability issue.

Ignition: The fleet of flying Corvairs is about 500 aircraft. More than 90% of them have a dual ignition system that I have built. Our system uses two redundant systems, one points based, the other a digital electronic system. The design has two of every part potentially subject to failure, but it utilizes one plug per cylinder. Six cylinder engines can fly on one cold cylinder, most 4 cylinder engines can not. We have dyne proven that a Corvair running on 5 cylinders will still make 78-80% power. Plug fouling is unknown in Corvairs because the ignition system is 40,000 volts and uses a plug gap twice as wide as a magneto system.

Fuel: The Corvair can use either 100LL or automotive fuel. It is not bothered by ethanol in the fuel.When Corvairs were designed, car gas was a lot like 100LL; for the last 35 years every mile driven by Corvair cars was done on unleaded car gas. Many engines like 912s and modern car engines do not have exhaust valves that can withstand the corrosive nature of 100LL. We use stainless and Inconel valves in Corvairs with rotators on the exhausts.

Maintenance: The Covair is low maintenance. The heads never need retorquing. The valves have hydraulic lifters and never need to be reset or adjusted. I dislike the term “maintenance free”, because it implies a “no user serviceable parts inside” disposable appliance mentality, but the Corvair is a solid, robust, machine which holds its adjustments, but our program is aimed at teaching builders to be self-reliant owners.

Goals: If one of your goals is to be the master of your engine and airframe, the Corvair is an excellent choice. There are many engine options for people who just want to buy something. Our efforts are aimed at expanding the personal knowledge and skills of each builder.

Made in the USA: In an era where everything seems imported and companies like Continental have been sold to the Chinese Government, We have kept the “Made in the USA” option for builders who prefer to employ fellow Americans. Virtually every part in the engine, with small exceptions like the distributor cap (made in Mexico), are made by American craftsmen. Because we also sell engines outside the US, we are a Net Exporter, helping correct the trade imbalance.

Corvairs have proven themselves to serve a very broad variety of builders. Many alternative engine options are offered only as a complete import, more of an appliance than a machine, with little or no consideration of the builders, skills goals, needs, budget or time line. The Corvair has options to address these valid considerations, because your power plant should conform to you, not the other way around.

This said, Corvairs are not for everyone.  In the 31 years I have been in the EAA and working with builders, the Corvair has always been very popular with ‘traditional homebuilders’, the people who have come to experimental aviation to discover how much they can learn, understand and master.  The expansion of the EAA has brought more of these builders, but it has also brought a great wave of people, incapable of distinguishing between mastery of an aircraft or an engine and just merely being its buyer and owner.  People who’s consumer mentality and short attention spans are better suited to toy ownership than mastery of skills and tools in aviation. Corvairs, and perhaps experimental aviation, are a poor match for such people. Many salesmen in our field will gladly sell anything to anyone with green money. I am an aviator, not a salesman, and the gravity of the subject requires more frank discussion and ethics than many salesmen bring to the table.

If you came to experimental aviation to find out how much you can master, not how little, then you are among the aviators who follow Lindbergh’s timeless 1927 quote: “Science, freedom, beauty, adventure: what more could you ask of life? Aviation combined all the elements I loved.”  Even if you are brand new to aviation, I am glad to work with you. I have a long history of working with builders of all skill levels. We have a number of successful builders out flying who are the masters of both their airframes and engines, who had never changed the oil in a car before building their plane.  If you got into experimental aviation just to buy stuff, then any salesman will do just fine for you. If you got into experimental aviation to learn, develop your own skills and craftsmanship and make things with your own hands, then who you work with really matters. You can’t become and old school homebuilder / motor head by buying things from salesmen. They have nothing to teach you. What you will do in experimental aviation is not limited by what you already know. It is only limited by what you are willing to learn, and selecting experienced people to learn from.  If you are here to learn, I am here to teach. It is that simple.

William Wynne

Basic Corvair information

Builders,

Here as a basic breifing on Corvair flight engines for builders getting a first look at using one.

Above, A  3,000 cc Corvair flight engine. I built this particular one for the SPA Panther aerobatic aircraft, and has powered the prototype aircraft through it’s introductory season. The Corvair is a popular option on more than 20 different experimental airframes.

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The Corvair is a General Motors designed engine, manufactured by Chevrolet.  1.8 million engines were built in the Tonawanda New York engine plant between 1960 and 1969. The Corvair has been flying on experimental aircraft since 1960, and I have been working with them as flight engines since 1989. It is a story of careful development and testing, a slow evolution to the engines we have today. It is ‘old and proven’ rather than ‘new and exciting.’

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– Configuration:  The engine is a horizontally opposed, air-cooled, six cylinder configuration. We only promote its use as a simple, direct drive power plant. The engine configuration is very similar to Lycomings and Continentals.

Displacement: The engine is effective without a gearbox or belt drive because it has a comparatively large displacement. We have versions that are 2,700, 2,850 and 3,000 cc. The smallest of these are twice as big as a Rotax 912.

Power: Corvairs have three different power ratings. 100, 110 and 120 hp. These correspond to the three displacements. They make their rated power at 3,150 rpm. They have wide power bands, making 75% power at 2,650 rpm. All engines will exceed their rated power at higher rpm, and they can be continuously run at full power at 3,600 rpm without damage.

Weight: The engine weighs 225 pounds ready to run. This is effectively the same as a Continental O-200. It’s installed weight is 35 pounds more than a 912 Rotax, 25 pounds more than a Jabaru 3300. The Corvair is 40 pounds lighter than a Lycoming O-235. 3,000 cc Corvairs are slightly lighter than 225 lbs. because we have special cylinders made for them which make these engine 5 pounds lighter.

– Reliability: From the factory, the Corvair made up to 180 HP in the car and turned more than 5,500 rpm. The engine is reliable and long-lasting because we are only operating at 60% of these levels. Conversion engines that run at the car’s red line rpm historically have short lives and cooling issues.

Cost: We sell complete engines from $9,750 to $11,750. However, 90% of our builders assemble their own engines working from our Conversion manual, DVDs, parts and support and a rebuildable core engine they pick up locally. Typically, they budget $6,500-8,500 to build a first class, zero timed, engine.

Cooling: The Corvair has a factory cylinder head temp limit of 575F. This is the highest limit on any mass-produced air-cooled engine ever built. The engine as also the first mass-produced turbocharged car. GM engineered the motor to have excellent heat tolerance and heat dissipation. In aircraft the engine typically runs at 325 to 350 CHT.

Parts availability: Every wearing part in the engine has continuously been in production for 5 decades. The engine pictured above, only has an original pair of cases, and oil housing and cylinder head castings. All other parts in the engine, including the crankshaft, are brand new. Many of the parts in the engine, like the lifters and valve train, are common to Chevy v-8s. There is no part availability issue.

Ignition: The fleet of flying Corvairs is about 500 aircraft. More than 90% of them have a dual ignition system that I have built. Our system uses two redundant systems, one points based, the other a digital electronic system. The design has two of every part potentially subject to failure, but it utilizes one plug per cylinder. Six cylinder engines can fly on one cold cylinder, most 4 cylinder engines can not. Plug fouling is unknown in Corvairs because the ignition system is 40,000 volts and uses a plug gap twice as wide as a magneto system.

Fuel: The Corvair can use either 100LL or automotive fuel. It is not bothered by ethanol in the fuel.When Corvairs were designed, car gas was a lot like 100LL; for the last 35 years every mile driven by Corvair cars was done on unleaded car gas. Many engines like 912s and modern car engines do not have exhaust valves that can withstand the corrosive nature of 100LL. We use stainless and Inconel valves in Corvairs.

Maintenance: The Covair is low maintenance. The heads never need retorquing. The valves have hydraulic lifters and never need to be reset or adjusted. I dislike the term “maintenance free”, because it implies a “no user serviceable parts inside” disposable appliance mentality. The Corvair is a solid, robust, machine which holds its adjustments, but our program is aimed at teaching builders to be self-reliant owners.

Goals: If one of your goals is to be the master of your engine and airframe, the Corvair is an excellent choice. There are many engine options for people who just want to buy something. Our efforts are aimed at expanding the personal knowledge and skills of each builder.

Made in the USA: In an era where everything seems imported and companies like Continental have been sold to the Chinese Government, We have kept the “Made in the USA” option for builders who prefer to employ fellow Americans. Virtually every part in the engine, with small exceptions like the distributor cap (made in Mexico), are made by American craftsmen. Because we also sell engines outside the US, we are a Net Exporter, helping correct the trade imbalance.

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Corvairs have proven themselves to serve a very broad variety of builders. Many alternative engine options are offered only as a “buy it in a box” import, more of an appliance than a machine, with little or no consideration of the builders, skills goals, needs, budget or time line. The Corvair has options to address these valid considerations, because your power plant should conform to you, not the other way around.

This said, Corvairs are not for everyone.  In the 25 years I have been in the EAA and working with builders, the Corvair has always been very popular with ‘traditional homebuilders’, the people who have come to experimental aviation to discover how much they can learn, understand and master.  The expansion of the EAA has brought more of these builders, but it has also brought a great number of people incapable of distinguishing between mastery of an aircraft or an engine and just merely being its buyer and owner.  People who’s consumer mentality and short attention spans are better suited to toy ownership than mastery of skills and tools in aviation. Corvairs, and perhaps experimental aviation, are a poor match for such people. Many salesmen in our field will gladly sell anything to anyone with green money. I am an aviator, not a salesman, and the gravity of the subject requires more frank discussion and ethics than many salesmen bring to the table.

If you came to experimental aviation to find out how much you can master, not how little, then you are among the aviators who follow Lindbergh’s timeless 1927 quote: “Science, freedom, beauty, adventure: what more could you ask of life? Aviation combined all the elements I loved.”  Even if you are brand new to aviation, I am glad to work with you. I have a long history of working with builders of all skill levels. We have a number of successful builders out flying who are the masters of both their airframes and engines, who had never changed the oil in a car before building their plane.  If you got into experimental aviation just to buy stuff, then any salesman will do just fine for you. If you got into experimental aviation to learn, develop your own skills and craftsmanship and make things with your own hands, then who you work with really matters. You can’t become and old school homebuilder / motor head by buying things from salesmen. They have nothing to teach you. What you will do in experimental aviation is not limited by what you already know. It is only limited by what you are willing to learn, and selecting experienced people to learn from.  If you are here to learn, I am here to teach. It is that simple.

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Click on the color links below to read more on this topic

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a) – Complete Lindbergh quote is here: The Quote, 1927, C.A.L.

b) – Explanation of machines vs appliances : Machines vs Appliances Part #2

c) – Story of real engines vs ‘ideal’ ones: Unicorns vs Ponies.

Questions from potential builders:

Builders,

Here are some questions that came in as comments on other stories:

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Frank Stephenson writes:

“While there will be many different results, I am wondering what the average time before overhaul may be. Also what are we looking at cost wise for one of these engines and the average cost of an engine mount? I am considering selling my current conventional geared C-172 with a C-O300B engine and buying or building something a bit smaller and more efficient. I really don’t know anything about Corvair engines other than I know of several folks who have utilized them, but I don’t really know anything about their results. I have found, in general, that automotive engines don’t make really good aircraft engines, but some VW engines I have known of are an exception and apparently the Corvair engines may be an exception.”

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Frank, the minimum time between overhauls on a well built engine is 1,500 hours. Ten years ago we listed 1,000 hours as a very conservative figure, since then, improvements like using valve rotators have driven the life span up significantly. The Overhaul cost on the engine is very low, on the order of $2,000 to replace almost all moving parts or recondition them. You can lean more at this link: Basic Corvair information I understand that many automotive engine engines have a poor record, but I have been doing this for 25 years, and we have earned an excellent one. You can read this link: Planes flying on Corvair Power, and see many examples. For the cost of motor mounts, just look at out catalog,http://www.flycorvair.com/, and page down to Group 4200, it lists the price of every mount we make.

I know VW engines have worked for many people, but I will put the track record for reliability, power and TBO of our work with Corvairs against any VW based engine. There is a lot of information on our main webpage, http://www.flycorvair.com/. I understand that it looks overwhelming, but better too much than to little.

Here is an important point: I don’t think efficiency is a good enough reason to move to homebuilding. Lets say your Cessna does 110mph on 8 gallons an hour. There are several Corvair powered planes that can do that on 5 gallons an hour, even some on 3 gallons an hour. But even if you were to cut your fuel costs on flying 200 hours a year from $8,000 to $4,000 per year, I don’t think it is enough motivation to send a guy to the shop for 1,500 building hours. The only people that consistently succeed at homebuilding are the people who inherently would rather fly something the personally built, and people motivate by the desire to learn new skills. I have met very few people motivated just to fly less expensively who thought in the long run that homebuilding was worth it. Consider this carefully, you may have a better time staying airborne in the plane you have.

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Steve Spears

“Sir, I am currently building a RW26 Special ll and I would like to use the Corvair engine. However, some people are telling me that it is to heavy for the aircraft. What are your thoughts and do you know of anyone who has used a Corvair engine in the Rag Wing aircraft? I read what you wrote about the Pietenpol and am encouraged that I can use the engine”

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Steve, I looked at this pretty closely for an hour the other night. I tend to think that a Corvair is too big to the R-26. The 912 appears to be as large an engine as people use. Several of Rodger Mann’s designs have flown with Corvairs, but I wouldn’t call any of them an ideal match. I am guessing that a Rotax 503 is really the optimum engine for many of his designs. For a comparison of how heavy duty a Pietenpol is built, the longerons in the fuselage are one inch square spruce from the firewall to the tail post. I am pretty sure the R-26 is lighter than that.

For any plane that you are wondering about Corvair power for, the best rule of thumb is asking if the same plane has flown with a Continental o-200. If it has, a Corvair will always work in it. For a comparison of the two engines look at this link:Corvair vs O-200….weight comparison and this one:Dynamometer testing the Corvair and O-200. We also have a lot of info on comparisons to 912s at this link: Testing and Data Collection reference page.  -ww.

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Group 2400-L Starter installation instructions.

Builders:

Our ‘ultimate’ evolution of starter systems is the 2400-L  series. It was flight tested on the SPA/Panther early in 2015, and has since become the benchmark for simple, ultra-light, efficient and powerful starters for Corvairs. We have produced several hundred, and they are now our standard starter we recommend to every builder.

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The great majority of flying Corvair powered planes utilize one of the Nippon Denso based starters we sold between 2002 and 2015. These are good systems, and they use the same basic starter design as most of the high performance aftermarket starters for Lycomings.  To justify a new generation of starters, the New 2400-L series would have to be significantly lighter, simpler to install, and be even more efficient. After a lot of R&D and testing, we met all these goals. The new starter is 3 pounds lighter, it has a very simple set up that takes only minutes, and surprisingly, it cranks the Corvair faster, while using less amps, and having a much lower voltage drop.  It meets these goals at a modest price increase over earlier systems.

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We sell the system as a complete kit which includes all the items in the 2400 starter group. This is explained in detail in the conversion manual. The included items are the Starter itself, the mounting brackets, the Gold top cover, and the ring gear.  The direct link to see the kit for sale is here: http://shop.flycorvair.com/product/2400-l-light-start-group-kit/

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IMG_9123

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Above, The 2400-L system atop my own personal Corvair engine. The starter is powerful enough to crank any Corvair (Dan Weseman has one on his high compression 3.3 Liter Corvair: SPA / Weseman 3.3 Liter Corvair now running) on a very light weight battery.  The view shows how compact the unit is, the starter motor itself is smaller than a 12 ounce soda can. The starter above sports black powder coating that we put on some 2400-L starters for aesthetic reasons. The 2400-L kits are specifically made to mate with Weseman Group 3000 5th bearings.

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IMG_2306

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Top view of a Corvair built in our shop, showing 2400-L starter arrangement. The black part is the starter motor, the silver part is the integral solenoid. The Top Cover, brackets, main starter plate, and the starter nose are all made on high end CNC machines here in the US, and for this reason they are very accurate and easy to set up.

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IMG_2312

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Rear view of 2400- L starter on the dipstick side (Cylinders 1-3-5) of the engine. Because this starter has a very stiff 3/8″ think billet main plate, it does not need a tail bracket like our previous designs.  The mounting bracket on this side has a 7/16″ bolt fixed in it. This is the pivot bolt for the adjustment. On installation this bolt is snugged up just enough to still allow the starter to pivots for adjustment. After it is set, the nut is tightened to 45 foot pounds.

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IMG_2313

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Above, the non-dipstick side (Cylinders 2-4-6) of the engine. This mounting bracket has a 3/8″-24 stud fixed in it. The main plate, seen in natural aluminum here, is actually sloted where the stud goes through it. This provides the adjustment for the mesh between the ring gear and the starter. Once the adjustment is set, the NAS locknut is torqued to 25 foot pounds and the unit will hold this adjustment for good.

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Instillation sequence:

1) The ring gear is mounted on the Gold prop hub using the hardware that comes with the Gold hub. Most people paint the ring gear before installing it, other wise it will rust. Powder coating is not recommended, as it tends to fill in the valleys between the teeth and affect the mesh.

2) The gold top cover is mounted on the case with the twelve 5/16″ fasteners, each with a lock washer under the head. These need a light coat of anti-seize  (like ARP lube)  on the threads. The heads of the two fasteners which go under the starter must be the “button head” style provided, for clearance. The four starter bracket mounting bolts clamp the top cover, making the total fastener count sixteen, matching the number of holes in the top cover. The top cover gasket should have a thin film of Permatex ultra grey RTV sealer applied to each side. Before putting the sealer on, match the bolt pattern on the cover and gasket to the case, it is not symmetrical.

2) Each mounting bracket is held down by two 5/16″ bolts with lock washers under the heads. These bolts should have a light coating of anti-seize (like ARP lube) on the threads where they go into the case. They are torqued to 15 foot pounds. Bolt down the dip stick side, but leave the other side off for now.

3) The starter is mounted on the 7/16″ pivot bolt, and the nut is just snugged up to take out the slack, but still allow the starter to pivot. Using a pair of pliers gripping the starter gear teeth, pull the teeth forward to their extended position. Sick a small screwdriver behind the clutch ( the round part behind the teeth) to keep the clutch/gear teeth  extended forward.

4) Install  the non-dipstick side bracket on the main plate by putting the 3/8″ stud through the slotted hole in the plate. put the nut on lightly.

5) Pivot the starter down to meet the ring gear, and when it is close, install the two 5/16″ mounting bolts in  the non-dipstick side bracket.

6) Put a 1/16″ drill bit or welding rod in the valley between the two ring gear teeth where the lowest starter gear tooth meshes. snug up both the 7/16″ pivot bolt nut and the nut on the 3/8″ stud. Push the starter down hard enough to pinch the 1/16″ drill between the ring gear teeth and the starter gear tooth, so it cant be pulled out with bare fingers. Tighten up the nuts fully, pull the small screwdriver from behind the starter clutch. Rotating the ring gear slightly should cause the 1/16″ drill to come out, and the starter gear will automatically retract. The starter is now set.

7) The small 1/4 spade terminal on the solenoid is connected to the starter switch; the outboard stud is where the 12V battery cable connects.

8) You can judge a good gear mesh by the sound. It will sound just like your car cranking if it is right. If it is too loose it will make excessive metallic grinding sounds, it it is too tight, the starter gear will hit the back of the ring gear instead of engaging it. If you want to test it, make sure you do so with the spark plugs in to provide a full cranking load. Without them, even a very loose mesh will sound good. BE VERY CAREFULL WHEN THE STARER IS HOOKED UP – EVEN IF YOU DON’T HAVE AN IGNITION OR CARB INSTALLED.  A cranking starter, even if the engine doesn’t start, will turn a prop 350 rpm, this is plenty of power to inflict a fatal blow. Even if you have no prop on, be careful, having your hand or shirt sleeve near the gear, could draw your fingers into the meshing gears. Anytime you have a battery near the system, use your brain, pay attention.

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IMG_2298

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Rear quarter view of the 2400-L starter system. It is an efficient, elegantly simple system.

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-ww.

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Getting Started Reference page

Builders,

Below are links you can click on in sequence that follow through a detailed series I wrote on Getting Started in Corvair building. They are detailed and long, but successful builders tend to spend the time to learn and make better choices. I wonder about people who decide to buy an engine or a plane of any kind after reading a 4 page sales brochure with less than 200 words on it. Hardly due diligence in a ‘flyer beware’ marketplace. If you would like to start with a simple three page spec sheet on the engine, read this link first: Basic Corvair information

Conversely, we offer a very detailed picture of exactly what Corvairs are about, what you can learn and achieve by building one, and the infinite ways you can build one that will conform to you needs, goals, skills, timeline and budget. The Corvair can be made to fit your project, you don’t have to rearrange your plans and budget to serve the company that is selling you an engine. Sounds funny when you put it that way, but that is just what most people do.

I could drive myself to madness by concerning myself with what the masses will or might do. In experimental aviation you don’t have to be concerned with what ‘most’ people are buying or doing (unless your goal is to be like everyone else rather that being yourself), you need only find the right path for you. Corvairs are not for everyone. The strongest appeal are to homebuilders with traditional goals of Learning, building and flying. Many people interested in experimental aviation today have short attention spans and shallow goals. They want to posses skills but are unwilling to learn; They want to have things but are unwilling to make them; they are unable to differentiate between going for a ride in a plane and being an Aviator.

If you want to learn, I have long proven I have things to teach; if you wish to build and be the master of your engine, we have a proven path; If you long to find your place among real aviators, we have a home for you. You do not need any prior experience, just a willingness to learn and a positive attitude. In 24 years we have shared our experience with hundreds of builders. If your goals match our strengths, we will be glad to work with you. -ww.

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

New Numbering System, Final, please print.

3,000cc Corvair (lower compression) engine

Builders,

Below is a look at an engine I just finished a few days ago. It is my own personal Corvair engine. We have several customer engines going together in the shop now, but I assembled ours in advance because I am shortly going to run a series of comparative tests with nitrous oxide injection. While the possibility of harming a motor is slight, you obviously wouldn’t test with an engine you are going to send to a builder.

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IMG_9120

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Above, break in run in our front yard. The engine is a 3,000cc displacement with 95 HP heads set up with a .050″ quench height. It has my own 5th bearing design as seen in this story: Group 3200, Wynne 5th Bearing .The Compression ration is about 8.4 to 1.  My intention is to run the engine primarily on 90 octane ethanol free fuel, commonly available in Florida for boats.  It’s only advantage over auto fuel is that it stores a lot longer without degrading. The engine will have no problem digesting 100LL, but I want to have a long term first hand study of lower octane fuel in Corvair powered planes.

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IMG_9117

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Above, I have actually owned this engine since 1991. It came in my 1967 Corvair Monza that was my daily driver for many years, accumulating 100K miles including a lap around America, ( look at the photo in this story: 2014 Conversion Manual Notes ) It went on to be the 2,775 cc engine at first flew in our Zenith 601XL in 2004, It was the test engine for my 5th bearing design in 2007, and it is staging this re-appearance as a 3,000 cc.  The engine has had roller rockers since 2004, and may have been the first engine ever to fly them. (No, they don’t make much power difference nor make the engine run cooler, both are misconceptions based on marketing claims which are only valid in limited circumstances.) To read more, look here: Pros and Cons of Roller Rockers. Over the years the engine has accumulated many details, most of which are things that we tested and found not to be a great value to most builders. If you look closely, it has ARP case studs (2003) ARP head studs (2004) and powder coated aluminum pushrod tubes (2007). and group 1800 powered coated lower baffles (2012)

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Above, a look at the topside. Almost all of the external conversion parts are our regular stuff. The engine has a HV-2000 rear oil case, a 2400-L Starter set up (the nose and bracket are powder coated black), a #2601 Gold oil filer housing, a #2802 block off plate, and an Adjustable Oil Pressure Regulator, #2010A. The top head nuts on the engine are Small Block Chevy rod nuts. This was an idea that morphed into #1706 head nut hardware, something Dan Weseman provides with finished heads.

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BTW, I was forwarded a picture of a first time builders enginge, a 3000cc motor. This guy made huge issue of objecting to using .041″ aircraft safety wire to hold the baffeling on the cylinders of his engine.  You can see this in the above photo as the neatly done stainless fine lines running at the base of the #6 and #2 cylinders. This is done because 3,000 engines have different cylinder castings which don’t fit the stock Corvair baffle clips. We have been using Aircraft safety wire for this task for more than 15 years, (because we used it on 3,100 cc Corvairs also.) The person, who evidently knows nothing about aviation, said “Bailing wire has no place in aviation.”

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Bailing wire? I have personal touched, with my own hand in museum restoration settings, a Lockheed SR-71, a North American X-15, and a Rockwell Space Shuttle Orbiter, all of which flew with Aviation Safety wire, so contrary to our new ‘expert’, it is approved for mach 3, mach 6 and mach 17 flight, as well as mach 0.12 experimentals.  Here is the stupid part: his forwarded photo shows that he painted his pushrod tubes flat black, which I have told people never to do because it makes them run very hot and gets the o-rings brittle. You know what actually has no place in aviation? People who can’t read. Perhaps a person shouldn’t be quite so proud of being from a state that ranks 5oth in the Nation in public education.

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Above, The engine at power during a 1 hour break in run. The differential compression test showed that the cylinders were perfect. The engine also has an #1100 cam:  Sources: Group 1100, Camshaft. This profile actually has slightly longer exhaust lobe duration than cams traditionally used. This doesn’t have a giant effect on normal engines, but it is a very desirable feature on ones using nitrous oxide. After some more time on the run stand we are going to progressively hit it with doses of N2O at 20, 25, 30 and 35 hp. The idea is to establish what is a safe level of power boost for 3 minutes. Contrary to what most people think this is not hard on an engine, as long as the fuel pressure never drops. I have worked with N2O on engines dating back to 1982, the stone age of commercial nitrous. Pushing a 550hp V-8 to 900hp is hard on it, but looking for a 20% power increase is not. Smaller engines like a Corvair flowing very low rates may run many minutes on a standard 10 pound bottle. The valve covers shown are the standard ones we sell in group #1900, like the ones pictured in this story: E-mail Now: Custom Valve Covers Available Through Monday.

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Nitrous boosts power in 3 ways sequentially: It is actually injected as a 1000 psi liquid, who’s basic evaporation robs all the heat out of the intake charge.  The temperature can easily drop below zero F, even in a hot motor. Then the N2O is compressed and heats above 800F, the molecule breaks up in a dissocation reaction, which raises the pressure in the cylinder, and frees up the oxygen. N20 has nearly twice the mass of oxygen as air, and this is then burned with additional fuel sprayed in. Think of this as performing a take off with your plane at a density altitude of 5,000′ below sea level. N2O works great, but it is very intolerant of anything that aggravates detonation, like not setting timing with a light, or using the wrong plugs, letting the engine run lean or not reading the instructions.  When you hear stories about to blowing up engines, smile politely and nod, and think “WW said it wasn’t for everyone, particularly people who can’t read.”

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I have no “secrets.” I have tried to teach everyone all the things we have learned over the years. Secrets are for people who want you to idolize them, have themselves remain ‘mysterious.’ To me, the only thing mysterious about such people is why potentially rational people abdicate from their ability to consider and learn, instead opting to spread myths about some alleged talents or knowledge that you are not allowed to look at. Think back to how people talk about others who own powerful vehicles, and realize that a lot of this is a weird form of hero worshp, peoplably because it takes less effort than learning what is going on.

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 Yes, I know a lot about Corvairs, but the goal has always been to share it with other builders. That is what the last two decades have been all about.

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-ww.

Sources: Choosing a 5th Bearing

This is part two in the ‘new sources’ series.

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Builders.

The most basic decision on building a Corvair Engine is which 5th bearing to use. While people still do build 4 bearing engines, and it is possible to later upgrade these with Weseman Gen I retro-fit 5th bearings, my conversion manual outlines the logic of why it is preferable to start the build with a 5th bearing, and why in the big scheme of things why builders on a budget should elect to delay things like radios or elaborate paint jobs instead of putting off a 5th bearing.

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5th bearings have been around Corvairs for more than 10 years. Between 1960 and 2005 virtually no Corvair used a 5th bearing, but with the increasing output and wider range of applications we used the Corvair for, it because understood that they are a very good idea on modern engine builds. Because the Weseman Gen I bearing is retrofit-able and very affordable, almost half the fleet flying before 2005 has be retrofitted with them, and with the addition of Gen II bearings for new engine builds, Weseman 5th bearings have come to completely dominate the fleet of flying Corvair powered planes. The Weseman’s have produced hundreds of them, they work, they are affordable, they are field installable by the builder in a few hours, They are built of the highest quality CNC equipment and they are well supported. For these reasons, they outnumber any other design by more than 10 to 1.

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In our Conversion manual, We discuss three different bearing designs. They are Group 3000 Weseman Bearings, Group 3100 Roy’s garage Bearings, and Group 3200, my 5th bearing design. This article series is on making good source choices for progress. I will cut to the chase here and say it plain: If you are serious about building and flying, Choose a Weseman Group 3000 bearing (either a Gen I or II) for your project, period.

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Above, Close up showing Weseman Gen II billet 5th bearing. Early models had heat treated cast housings, but for many years, both Gen I and Gen II Weseman bearings have Billet aluminum housings made on CNC machines by a major aerospace manufacturer. These housings have bearing inserts from an American V-8 that are easily and inexpensively replaceable, without having to split the case. The housing is indexed to the case, and can be removed and replaced, and it goes right back into index. I have installed dozens of these on Corvair flight engines. They are readily available, in stock, on the shelf items available, along with matching cranks from the Weseman’s:

https://flywithspa.com/corvair/

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Consider this: I have my own bearing design,  Group 3200;  It has been proven for almost ten years, it has flown hundreds of hours, I have one on my own plane. I could promote them and sell them for a profit, but I don’t. My motivation isn’t to just sell things and make money, it is to recommend the best parts and sources for builders, and this is more important that egotistically promoting something because I thought of it and made it, when there is something that when considered objectively, better serves builders. This is why all the production engines I build have Weseman bearings on them, and why strongly recommend them to every builder.

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The bearing from Roy’s garage is Group 3100 in the manual.  It is a good design, and no one has done more than I have in the past to promote Roy’s work as an option. The limitation of the design is that each case and crank must be shipped to Roy, where the bottom end has to be hand machined by Roy. This is a labor intensive process, and if he was doing nothing else, he would be pressed to make 20 assemblies per year. In the past I have had Roy as a guest at many Colleges and for several years in my booth at Oshkosh. For a long time he has had a back order list well over a year. Instead of ‘sticking to the knitting’ and addressing this, he has spent hundred of hours on “R&D” goose chases. At the start of 2015, I quietly told him I was no longer comfortable promoting his work or having him come to colleges, as it didn’t seem he was serious about getting caught up. His response has been to spend his time developing a ‘secret’ modification to allegedly make 20% more power, telling builders that our CNC parts don’t fit Corvairs, and trying to promote the idea that he alone, a guy without a pilot’s nor A&P licenses, who has never owned any plane, somehow knows better than anyone else how to build and operate these engines. I have been working in experimental aviation for more than 25 years, and let me offer the observation that many people who started with a good basic product, but came to see themselves as more brilliant than everyone around them, didn’t last much longer.

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Many builders understand that it will take several years, on average to build their plane. That is fine, but builders need to choose their sources carefully. and not start off by sending their case away for a year or two when a better option exists, when they can make immediate progress. A builder, signed up for a college, can simply call the Weseman’s and buy a bearing right off the shelf, we can bolt it together at the college, and with little effort head home with a closed case. That is getting a year head start on the process. It also costs less money. For anyone who might claim that my endorsement of the Weseman bearing is related to money, guess again. When I put one on an engine, I pay full price for it, and because I live in the same state, I pay tax on it. My promotion of it is simply because it is the best option for any builder who wants to make progress.

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-ww.

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Sources: Group 1000, Crankshaft

this is part five in the ‘new sources’ series.

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Builders;

Ok, so far in this series on accelerating your engine build, we have followed the basic path that builders go through:

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First, a look at working with the best sources for progress:

Revised sources, listed by Group numbers, Aug. ’15

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Second Decide what 5th bearing to use:

Sources: Choosing a 5th Bearing

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Third, Decide what displacement to build:

Sources: Choosing a displacement.

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Fourth, review the first milestone, getting to a Closed case:

Sources: Closing a case

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Now lets move to looking at the Groups individually. The first one in the conversion manual is Group 1000, the Crankshaft group.  While it is discussed in great detail in the Manual, the focus here is on where do you have it processed if you want to make progress on your engine? This question has one simple answer: You have your crankshaft processed by the Weseman’s ( https://flywithspa.com/corvair/ ) or you buy one of their new USA made Billet Cranks. The have processed exchange cranks on the shelf, and you can begin your engine build this week, not next year.

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Above is a close up of a Gen II Weseman bearing journal on a re worked GM crank. The Gen II arrangement comes already installed on the crank, match ground in place. This is the correct choice for progress. After torqueing the case halves, the housing installation is a simple matter. It isn’t a speed contest, but I have personally done them in under an hour. First time builders at Colleges do them in 3 hours all the time. The Weseman’s have a simple loaner tool kit available, and I have my own I bring to Colleges. Buying these parts, and putting them together with your own hands is what the core of the Corvair movement is about. This is a far better option for progress than sending your case off to an alternative 5th bearing with a multi-year waiting list.

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Deciding to work with the Wesemans for your crankshaft is a natural. They are serious enough to have carefully developed a very detailed process, and now send cranks through it a dozen and a half at a time.  I was impressed enough with their methods that I took the crankshaft out of my own personal 3,000 cc engine and replaced it with  another GM crank that went through their process, simply because The Wesemans processing involves an extra step of stress relieving the crank before working on it, and this is an undeniable improvement over previous methods. They are the only people working on Corvair cranks who do this.

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The Wesemans process Gen II bearings for the same cranks, so you can make one call to them and send in your core crank for an off the shelf process exchange crank, that already has a specific, serial numbered,  5th bearing that has been matched to that crank. It is one stop shopping, with very little wait. Having these two elements will cover both Group 1000 and Group 3000 in your build. This is the smart choice if you want to make progress.

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You can review their website in detail, or contact them to review pricing and options. They also have Billet cranks, and they are evaluating the stroker Billet crank which is at the heart of their 3.3 liter motor project.  While the Billet cranks are very fine pieces of machinery, about 90% of the engines going together at Colleges are Gen II Weseman bearings that have exchange GM cranks that were processed by the Wesemans. Read the background on their site, either one is an excellent choice.

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Just to head off any suggestion of this from people who compulsively assume that every suggestion they read is a paid endorsement, I will state for the record that I pay full price when buying cranks and bearings from the Wesemans, including paying Florida sales tax, which means I actually pay more for the stuff than builders living in the other 49 states. If this is someone’s idea of a clever monetized endorsement strategy, they need a new conspiracy theory.  I recommend these parts simply because they work, they are available, they are a good value, and they serve builders goals. It is that simple. In the long run, all of those things also serve the reputation of my work making the Corvair a viable American made option for homebuilders.

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-ww.

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Running your engine “Over-square”?

Builders:

There is a long standing piece of “hangar wisdom” That says you should never fly a plane “Over-square” . This condition is defined has having a higher manifold pressure in inches of Hg than you have RPM in  hundreds. Example: 25″ map and 2400 rpm is said to be “over-square”, where as the reverse, 24″ map at 2500 rpm is said to be “under-square”. This rule is brought up primarily to warn pilots about putting the engine in a condition where it might be prone to detonation.

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Like many things said in hangar stories, there is some element of original truth in this, but it doesn’t apply to all engines nor conditions. In the end it was supposed to be a little memory device for those unwilling to understand the larger principle.

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The origins of the statement are of attributed to being a good way to run Lycomings, or more particularly Lycomings with constant speed props. Over time, the “over-square” rule became something that people tried to apply to any engine in any situation. But a basic look at a trip around the pattern shows that the rule doesn’t work, not even in Lycomings; If you are near sea level and begin your take off roll at wide open throttle, your map will be darn near the outside air pressure, very close to 29.92″ on a standard day. Since no direct drive Lycoming with a fixed pitch prop turns 2990 rpm static, every take off is “Over square.” Even Constant speed equipped planes have redlines between 2700 and 2800 rpm, and thus would still be “over-square on take off.

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So what protecting these over-square planes from detonation on takeoff? Something very simple. Aircraft carbs, by design, run rich at wide open throttle. In private pilot school many people were told this was for “Fuel Cooling” the air-cooled engines, but that isn’t what is going on. The mixture running rich at wide open throttle effectively increases the comparative octane of the fuel. When you look at Octane ratings of old fuels like 80/87 or 100/130 or 115/145, these dual ratings reflect the comparative detonation resistance both lean and rich.  regardless of it’s name, any fuel will have more detonation resistance when the mixture is rich, and aircraft carbs set properly do this for you.

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Lycomings and continentals are configured this way, and if you have a properly set Stromberg or Marvel carb on your Corvair, it will do it also. However, you have to remember that it is always preferable to run the carb wide open when it is heavily loaded, ie, “Over-square”. Never let anyone talk you into backing off the throttle slightly on climb out, it is a very poor practice.

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The way to make sure your carb is set correctly is to tie the tail of the plane to something solid (not just chocks) and run the engine up to full static rpm. Give the engine a few seconds to stabilize, and then just barely pull the mixture out slightly. If it is set correctly, the rpm will increase as you lean it out, because you are going from an anti-detonation air/fuel mixture of say 10:1 toward best power at 12:1.  The power goes up, so the rpm will climb slightly. This is a good condition. If your carb doesn’t do this, it isn’t set rich enough. You can also watch this on your EGT.

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Where the warning comes into play is avoiding running an engine over-square in cruise settings where the throttle is partial open, and there is no additional richness to suppress detonation. Many times people refer this condition as “Lugging” the engine.  With Corvairs, I consider it very important that the engine turn at least 2,700 rpm static with the prop pitch set for flight. This way, on every take off and climb out, The engine will be operating close to “square” which minimizes the chance of detonation, and additionally the engine has substantially better seat of the pants detectable performance with just 100 more rpm static.

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Some builders, particularly Pietenpol builders like bigger wood props that often yield low static rpms in the 2400-2550 rpm range. I feel that this is an undesirable condition because such a prop tends to “lug” the engine, not just restraining it’s performance, but it is prone to cruising in a condition of low rpm and higher manifold pressure, but without the carb being in the wide open throttle position. Many guys feel that flying around with a larger wood prop at lower rpm is easier on the engine, but I can make a pretty good case that just the reverse is true, especially if the builder ever runs car gas.

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More Rpm will not hurt the Corvair, keep in mind that it did more than 5,500 rpm in the car and was designed to cruise in the car over 3,000 rpm. Your aircraft engine is far better built than any stock Corvair Car engine from the factory, so more rpm will not hurt it, but loading it at lower rpm just might.

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-ww.

 

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Above, a new 2,850 running  on the test stand in our front yard. During the cam break in period, (20-30 minutes) We run the engine between 1800 and 2200 rpm. The throttle is only part of the way open to do this. During the later part of the break in runs we run the engine as high as 3,200 rpm. At that condition the MA3-spa carb on the run stand is wide open and the O2 sensors and the egt’s indicate the engine is in the anti-detonation rich zone. Read more at this link:  New 2850cc / 110hp Corvair in photos.

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Center, above Joe Foss (USMC-CMH) stands with Charles Lindbergh in the south Pacific in WWII. Lindbergh was a factory rep for Vought, and one of the things he taught pilots was how to get extremely good range by running their engines massively “Over-square”, (very low rpm, high blower and high prop pitch) It worked, but the training included elements of making sure the air/fuel was very rich. Foss went on to be the Governor of South Dakota, Commissioner of the AFL, host of “The American Sportsman” and president of NRA.

Compression Ratios, Fuels and Power Output

Builders:

Here are three topics that are related. Although the conversion manual covers this in some detail, I will put a short summary here.

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We have 3 popular displacement s for Corvairs 2700, 2850 and 3000 cc (read more: Sources: Choosing a displacement.)  The latter two are made with a very special dish in the piston to lower the static compression, but keep the ‘quench area tight. On any of these displacements you can either put lower compression 95 hp heads, or you can put higher compression 110 hp heads. Right there you have six combinations with different compression ratios, but it is also possible to build engine with high or lower compression, but those six are the popular ones, and having the option allows Corvairs to suit different builders purposes.

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The two basic rules are: The higher the compression, the more power the engine will make….and There is a limit to how much compression you can use with car gas. The commentary here is general, but it comes running engines on our own planes from 7.7:1 compression (1998 2700 engine in our Pietenpol) to 11:1 compression (2005 3100 engine in our 601XL) I write this as a guideline, if you have a specific application, feel free to ask in the comments section.

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Basically any of the three displacements with 95 hp heads will have compression ratios from 8:1 to 8.5:1. Engines built with 110 hp heads will have ratios from 9.0:1 to 9.5:1. The variation is mostly in the machining done to the head gasket area, and the actual gasket thickness.

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The First question is what is the lowest Octane fuel you will ever use in your plane? In the answer is “I will never put anything but 100LL avgas in my plane” then you can use any compression ratio you like up to 11:1. Your engine will make about 5% more power for each whole point you raise the compression. But….you can never, not once, ever, run the engine on car gas, even 93 octane car gas if the compression is much over 9.5:1. 100LL is great fuel. yes engine can be detonated on it, but this is done by leaning the motor out far too much or not having the timing set correctly. Our 11:1 compression engine flew more than 600 hours on two different airframes The first 200hr was 11:1, we dropped it slightly to 10.5:1 for the rest of its time) It never detonated at all, and it never saw a drop of car gas either. 100LL when running slightly rich has a comparative octane of nearly 120.  Keep in mind that many people swear they will use nothing else, but later after the 40 hrs. are flown off, some people start getting cheap, and the are tempted to run car gas in a 9.5:1. They might get away with it under some conditions, but sooner or later, they will pay.

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Let’s say you are going to run ethanol free 93, or some mixture of this and 100LL, how high is smart to go? You could run up to 9.3:1 and get away with it, as long as you don’t excessively lean it. But what is the benefit of running on the ragged edge? If your engine is built with a ratio of 9.0:1, there will be hardly any measurable performance difference, but it will have a large increase in resistance to detonation.

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What about running 91 or 92 Octane car gas? Then it seems prudent to shoot for the lower range offered by using 95 hp heads. I have never been interested in speculation on what “should work”, I am much more interested in builders developing enough judgment to understand they are far better off with set ups that have a greater margin of safety than a slight performance edge.

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Examples:

Woody Harris , who’s plane is pictured below, started flying with a 9:5 to 1 compression 2700. (Flat top pistons and 110 hp heads). Because he was planning on switching to a Turbocharged installation, he went to an 8.25:1 2,850. (dished pistons and 95 heads). Woody had enough fun flying around, that he didn’t get to turbocharging. Woody has long reported that the power output between the high compression 2700 was about the same as the low compression 2850. This isn’t a surprise. Woody mostly flies on 100LL, but if he or anyone else was planning on running 91-92 octane fuel, they would be vastly better off with the lower compression 2850.

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My own 3,000 cc engine: Is set up at 8.3:1 compression (dished pistons and 95 heads) Although it might make 6 to 8 more hp if the compression was raised to 9.5:1, I don’t care because I am not running 100LL, my choice is to run ethanol free boat gas, which here in Florida is 90 octane and sells for about 10 cents a gallon more than 93 with ethanol. This week that is $2.80 a gallon. This is a very clean burning fuel and  it stores for a long time. On a cross country the engine will not care if it drinks some 100LL, again the compression ratio is determined by the lowest octane you will use, not the highest.  A few more hp isn’t going to make the Wagabond into a speed demon, I am after absolute long term reliability and being able to run any fuel available.

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Ron Lendon’s 2,850: Ron built a clone of Woody’s 2,850 engine with dished pistons and 95 hp heads. Recently he changed to flat top pistons and 110hp heads. This changed his compression ratio from 8:1 to 9.5:1. Yes, this will make more power, and it is OK because Ron says that he only runs 100LL . In short, he didn’t start with the highest performance option for the fuel is was going to use. Ron has worked for GM in their enginnering department for decades, so perhaps like most people who saw fuel prices in 2009, he might have been thinking about auto fuel then. But it pays to plan around the fuel you will eventually use. To keep things in perspective, I am sure that a 601 with a low compression engine and wheel pants met a 601 with high compression and no pants, the one with wheel pants might be faster.

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In the above photo, Woody Harris’ 2,850cc Zenith 601B sits at the end of the ramp in North Carolina at First Flight Airport with the Wright Brothers Monument in the background. Woody’s home airport is in California. He has nearly 500 hours on the plane without issues. read more:Woody’s 2,850cc Corvair/601XL hits 400 hours.

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Woody in the Grand Teton National Park WY

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Lest anyone think that low compression engines don’t make good power, above, Woody flying over Grand Teton. He often flies around the Sierras, and has flown to the highest and lowest airport in California in the same day.

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Above, a drop forged, made in the USA piston for the Corvair. The  displacement of this piston is 2,850 cc. read more: Turbocharging Corvair Flight engines Pt. #2

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2005 photo of our 601XL in front of our Edgewater hangar. The engine is a 3100 cc with 140 hp heads, oversized exhaust and 11:1 compression. Because it was a tail wheel and low drag it was fast. With wheel pants and the right prop turning 3,500 rpm, this plane could exceed 145 mph at sea level. People asked about weight, but at the 601’s low wing loading, it is slightly faster when loaded. They are good planes, but other than demonstration purposes, anyone really concerned about getting the last mph out of a 601 probably picked the wrong plane. It beauty is in utility, not speed. Note the size of the inlets: Here we have the most powerful Corvair engine that builders have heard of, yet it cooled itself just fine in hot Florida with 4.75″ inlets and a front alternator. It is a myth that this installation needs giant inlets to cool itself.

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Same plane, at sun n fun 2006. Sensenich prop was faster, but didn’t climb as well. I could have built the same engine for the plane we have today, but instead I chose something on the other end of the compression scale because I don’t wish to be tied to 100LL forever. Take your pick, what ever makes sense to you.

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Above, Dr. Andy Elliott, of Mesa AZ with the same engine on his 601XL. The photo was taken at Oshkosh, so it is safe to say the plane flew without issue. Andy flew the engine another 400 hours. His state has the highest summer temps of anywhere in the US, and yet the high performance engine cooled through the same size inlets. Andy’s plane could do nearly 140 mph. The power was a factor, but aerodynamics matter more and are cheaper. Before selling the engine to Andy, I reduced the compression slightly, but he still knew to always run 100LL.

-ww.

:)