Experimental Aircraft Association

Cincinnati, OH
Chartered since 1966
www.eaa174.org

<< Next Meeting: Sun, Jan 18, 2:00 PM >>

January, 2004

   The Corvair Engine
    by Gary Collins

It is said that engine development drives aircraft development. It works on another level too. My first glimmer of interest in building a plane came when Neil Hulin brought some Corvair engine parts to an EAA chapter meeting and described how it would power his Zodiac 601 XL. Then at Sun-n-Fun 2003 I went to a forum by William Wynne on the Corvair engine. He preached a powerful sermon that morning and I was hooked. I was volunteering in the Forums area and the headquarters was near the tent for auto engine conversions. I hung around and listened to the patter between Wynne and Corvair builders and potential builders. Before I left Lakeland, I bought a conversion manual from Mr. Wynne and when I got home I began to study it and to look for a 1965-69, 110 hp Corvair engine, which is the optimal engine for conversion for aircraft use. Such engines can be found for $100-200 and can be made into a direct drive 100 hp aircraft engine that weighs the same as an 0-200 Continental for about $3000. That is less than half the cost of a newly overhauled 0-200. There are some compromises with our usual concept of an aircraft engine but there are some nice benefits as well – they run almost electric motor smooth. Garry Howell decided he would like to go in with me and that made the whole project feasible. We found an engine at John Coyne’s Boot Hill salvage yard.

The Corvair automobile came out in 1960 and Bernie Pietenpol installed a Corvair engine in a J-3 Cub and flew it that year. He went on to install the Corvair in his Pietenpol Aircamper homebuilt and developed plans for a very simple but functional airplane engine conversion. Pietenpol did not do a lot to the engine. It retained the blower fan for cooling and the stock camshaft. He worked out a retention method for the drive flange and a way to use the oil supply to heat the carburetor for carb ice protection. The starter was removed and most used some kind of alternator since the standard distributor was retained. The engine set up this way will produce about 75 hp. These conversions have been quite dependable. So the Corvair has been flying for over 40 years.

Now some facts about Corvair engines. We are talking about a six cylinder horizontally opposed, air cooled engine. The 1960-1963 engines were 140 or 145 cubic inch engines. From 1964 on the displacement was 164 cubic inches (2700 cc) but the 1964 engines have smaller head gaskets making them less suitable for conversion. Some 164 cubic inch engines were rated at 95 hp and do not have the harmonic balancer (torsional vibration dampener). We have all heard about torsional vibration problems in aircraft power systems and a dampener is a great help on the Corvair even though it is direct drive. The harmonic balancer is the external crankshaft pulley that was used to drive the original cooling fan. It is made in two pieces that are bonded together with rubber between. The 110 hp engines built from 1965-69 have the better head gasket and the harmonic balancer. In the car these engines had two carburetors, one for each bank of cylinders. The engine was also made in a 140 hp

EAA – Talespinners – Chapter 174 is a 501(c)(3) exempt non-profit organization, whose principle objective is to provide educational assistance in the fabrication and restoration of classic and experimental aircraft. This newsletter is produced for the members of EAA Chapter 174 and the Cincinnati community to provide information on Chapter activities and to alert members of other potentially useful information. Any actions based on, or reproductions of information contained herein, are at the sole risk of the user. Any technical or regulatory information must be verified by the user. Neither the EAA and Chapter 174, nor the newsletter staff assume any responsibility for the correctness of the information contained herein.

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