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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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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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.

About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at www.FlyCorvair.com and in more than 50 magazine articles.

3 Responses to 3,000cc Corvair (lower compression) engine

  1. dan glaze says:

    Don’t ever walk under a KC-135, they must have 10 miles of safety wire on them, might cause them to just fall out of the sky. Dan-o

  2. Sarah Ashmore says:

    “Baling Wire” Has No Place in Aviation ??? That Guy has No Place in Experimental Aviation !!!
    He should never be allowed to fly anything but a certified aircraft that is completely A&P maintained or with his attitude his will need a prearranged grave plot and headstone.

    I happily followed the instructions and attached the baffles with heavy “Safety Wire” as the instructions said along with using White Powder-Coated push tubes. Anything else would have been incredibly stupid in my opinion.

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