Corvair, General Motors (US)

Corvair air-cooled, horizontally-opposed, six-cylinder automobile engines have been converted to light aircraft engines since the Corvair was introduced. Corvair was the Chevrolet brand name for its series of rear-engine compact cars built between 1960 and 1969. The Corvair and its engines were not duplicated within the rest of the General Motors Corporation range. Corvair models were available with both normally-aspirated and turbocharged engines. Both of these types have been converted to aircraft use, but not with the production turbocharger, which is too heavy.

It must be borne in mind that General Motors and Chevrolet have never, and do not now, authorize the use of Corvair engines or parts by any company, nor do they represent or warrant that their engines are suitable for use in aircraft of any kind. Any company modifiying Corvair auto engines for aircraft use is not affiliated in any way with General Motors or Chevrolet. This is the policy by most of the auto manufacturers whose engines have been adapted and converted for aircraft use. In the experimental aircraft community, these engines are generally classsified as "Alternative Engines". Everyone dealing with them must appreciate that they are classified as experimental when they are not type certificated by a governing national authority. No Corvair conversions have been type certificated in the US.

Websites for what are called "Alternative Engines"; i.e., those based on automobile, motorcycle, marine engines, etc. (and not designed specifically as aircraft engines), are listed here. Corvair engines are among those considered. Moreover, other specific Websites may be found, if desired, by use of search engines; e.g., Google and Yahoo.

Contact Magazine Website.

Kitplanes Magazine Website.

Mike Kraus' Homebuilt Homepage, under "Vendors".

Ron Wantajja's Sea and Sky Aviation Page.

Ultralight News Website.

Jake Crause's Homebuilt Airplanes Website.

Eric Ulmer's Homebuilt Aircraft Engine Directory.

Corvair engines known to have been converted to light aircraft engines are listed below with notes about their auto usage. The format is to list all of the basic Corvair engine designs first. After that, a section on aircraft applications by Corvair converters is presented, although neither the converter nor the specific Corvair engine models are known. These applications come from various Websites (including, "Jane's All the World's Aircraft", "Kitplanes" magazine, and the EAA's "Sport Aviation" and "Sport Pilot & Light Sport Aircraft" magazines. Then, the present-day firms are treated in the usual format of this Compilation Website with separate pages for details of their particular conversions. Patrick Panzera's Corvaircraft Website is very informative about Corvair conversions and applications. Also, Issue #75 of Contact Magazine, dated 2/12/04, is dedicated to articles on modern Corvair conversions. Panzera is also the editor of this magazine. Finally, as described on a separate page, The Corvair Authority, operated by William Wynne, sells conversion plans and has been very active in encouraging and assisting Corvair conversions on The Corvair Authority Website.

Corvair engines have been converted for use in homebuilt, experimental, non type-certificated light aircraft by individuals working on their own and by means of conversion manuals sold by small firms. Stock Corvair engines provide an adequate power-to-weight ratio so that direct drive is feasible in many applications. Thus, most Corvair conversions use direct drive of the propeller and thus avoid reduction of propeller rpm from that of crankshaft rpm; i.e., they do not make use of Redrives, or as they are called in this compilation, Propeller Speed Reduction Units (PSRU). Some converters do use PSRU's and a separate section below discusses those that are commerically available.

The earliest champion of Corvair conversions was the late B.H. (Bernie) Pietenpol, who found them very well suited to power his Pietenpol Air Camper and Sky Scout designs that date from the late 1920's and early 1930's. Some interesting information about Pietenpol's career can be found in EAA's "Sport Aviation" for 12/99. He is reported to have made his first Corvair conversion in 1960. This O-140 conversion delivered 65-70 hp. Besides his own aircraft designs, Pietenpol converted a Piper J-3 to Corvair power. Pietenpol's conversions included the stock Corvair cooling fan. Later converters found that they could dispense with the fan and its weight.

Other notable early Corvair converters were Waldo Waterman in 1969, for his Waterman Chevy Bird (Chevy Duck when on floats) [N262Y], Don Taylor in 1976, with a belt-driven PSRU, for his Taylor Tinker Toy [N5DT], and Clarence Huddle (SA7/79). Willis Dunham led a forum on Corvair conversions at Oshkosh on 7/31/79 (SA7/79).

A 1/3 Corvair HOAE was initially developed from 2003 by UltraVair Aviation. In about January 2008, The Corvair Authority assumed responsibility for further development and marketing of these engines.

Finally, although it is not strictly within the scope of this Website, it must be pointed out that Daytona Airmotive of Ormand Beach, Florida displayed an inline 3-cylinder engine that was 1/2 of a Corvair, geared to N/A, at Sun'n'Fun for 1978 (SA4/78, including a photo).

Six-Cylinder Corvair Engines

O-140 - - {3.375 / 2.600 / 139.6} / {85.7 / 66.0 / 2287}

Same stroke as O-145.

These are engines used in the 1960 auto models.

O-145 - - {3.4375 / 2.600 / 144.8} / {87.3 / 66.0 / 2372}

Same stroke as O-140.

These are engines used in the 1961-1964 auto models.

O-165 - - {3.4375 / 2.937 / 163.5} / {87.3 / 74.6 / 2680}

Same bore as O-145.
Same stroke as O-170, O-190.

These are engines used in the 1965-1969 auto models.
Converters: AeroMax Aviation, The Corvair Authority.

O-170 - - {3.500 / 2.937 / 169.5} / {88.9 / 74.6 / 2778}

Same stroke as O-165, O-190.

These is a modified version of the O-165 with the bore increased. It is described in KP4/05, 4/06, 3/07, and 3/08.
Converters: The Corvair Authority, VairForce.

O-190 - - {3.701 / 2.937 / 189.6} / {94 / 74.6 / 3106}

Same stroke as O-165, O-170.

This is a modified version of the O-165 with the Corvair cylinders and pistons replaced with 94mm (bore) VW cylinders and pistons. An earlier (1960's) Corvair/VW hybrid by Bob Huggins (US) is discussed briefly on the VW Webpage and in APrg11-12/65.

Several aircraft powered by Corvair O-190 engines have encountered crankshaft failure during flight. This has been documented well by William Wynne on The Corvair Authority (TCA) Homepage under "crankshafts", as well as by Mark Langford (failures in 2005 and 2008) on his Website, by Roy Szarafinski on his Roy's Garage Website, and by Dan Weseman on his Fly 5th Bearing Website. These failures have been attributed to the necessity for an additional, fifth, front crankshaft bearing to reduce crankshaft stress from engine- and propeller-generated time-varying loadings. These failures have been noted especially for the O-190 engine with its higher rpm, but can occur on Corvair O-165 and other versions as well.

Szarafynski, TCA, and Weseman, have each developed their own, proprietary, fifth bearings, which are available in commercially-available kits as described on their Websites. It should be mentioned as well that AeroMax Aviation offers complete Corvair O-165 conversions with their "Integrated Front Bearing" technology, as discussed on their AeroMax Aviation Website.

Converters: SC Performance (US); The Corvair Authority (US).

Applications of Corvair engines built by unknown converters using unknown Corvair engine types to aircraft are:

(Switzerland) Schretzman S.W.1 Pegasus. (US) Bensen Gyrocopter; Bowers Fly Baby; Corbin Jr. Ace; Fisher Horizon; Hatz CB-1; Heath Parasol [N838WL]; McLaughlin Sky Buggy [N28367]; Pfeifer Sport (1975 replica by Pfeifer of his 1936 original); Pober Jr. Ace; Quickie Q2; Rand-Robinson KR-1, KR-2; Roloff, Liposky & Unger RLU-1 Breezy; Rutan Vari-Viggen; Viking Dragonfly; Volmer VJ-22 Sportsman [N2392D]; Wittman Buttercup, Tailwind.

Firms known to have offered Corvair conversions for experimental aircraft, now or in the past, and which have a Website, are:

AeroMax Aviation with the AeroMax Aviation Website.

Magnificent Machine, LLC is presently manufacturing Corvair aircraft engine conversion parts for O-165 and O-190 versions; specifically their trade name MagVair cylinders, crankshafts, oil pans, connecting rods, and valve covers; see the Magnificent Machine Website. This firm hopes to manufacture and assemble complete MagVair Corvair conversions in the future.

SC Performance (US), as reported on Mark Langford's Website.

The Corvair Authority (US) with The Corvair Authority Website.

VairForce (US) with the VairForce Website.

Firms known to have offered two-cylinder Corvair conversions for experimental aircraft, now or in the past, and which have a page in this Compilation, are:

The Corvair Authority (US) with The Corvair Authority Website under an agreement with UltraVair beginning January 2008.

UltraVair Aviation (US) no longer has a Website.

Firms known to have offered PSRU specifically for Corvair conversions, now or in the past, are:

VW Engine Centre (RG Experimental Aircraft Engines) (Australia) with their VW Engine Centre Website uses helical gears to achieve propeller rpm at 0.625 of crankshaft rpm. The firm has a distributor in the US, which is listed on the Website.

Sports Specialties, with telephone number (775) 813-1832, are manufacturing Rinker gear-driven PSRU's and other Corvair conversion parts. Four different reduction ratios are available, but are not listed in their current classified advertisements; e.g., (SA1/05). Bud Rinker, of Santa Barbara, California, originally built Corvair gear boxes from VW parts (APrgHBW71).


Updated 10/15/09