Azalea Aviation

Bill Clapp remains a busy man, running an FBO, flight school, Saberwing aircraft and the Spyder Corvair engines aimed mainly at powering Saberwing Experimentals. His Corvair-based offerings are the Spyder 100 and 120 engines, although a turbo version has been prototyped.

There are no mechanical changes to the two production engines for 2023, just a relatively small cost increase thanks to general inflation of shipping and other costs.

Technically the naturally aspirated 100-hp engine is built from reconditioned GM parts reinforced by a steel front hub on the crankshaft, an added front main bearing, nitriding, a 30-amp rear-mounted alternator and plenty of new service parts.

The 120-hp version gets its oomph from a brand-new, counterweighted, 1/4-inch stroker crankshaft taking it out to 3.1 liters. This is without having to cut the case for overly large cylinders, thus preserving case integrity.

All Spyder Corvair engines are built to order, so count on some lead time. Clapp does keep a generous supply of core engines and associated parts in-house; typically there is no delay hunting down basic engine parts although 120 crankshafts were proving somewhat troublesome at our deadline.

While waiting, customers can review a multitude of Corvair teardown, operation and other manuals at Clapp’s Azalea Aviation website. Those traveling can now find Azalea Aviation fully transferred to their new location in Quitman, Georgia.

Sport Performance Aviation

Dan and Rachel Weseman own Sport Performance Aviation (SPA), maker of the Panther sport plane powered by Corvair engines, among others. From the beginning Dan and Rachel have partnered with Corvair uber-guru William Wynne, who still builds their Corvair engines for them.

Since the latter part of 2022, SPA has increased their association with Wynne’s FlyCorvair business by offering a core engine only, then directing the customer to source the accessories, oil pan, pushrod tubes, some valve train hardware and so on directly from FlyCorvair. The parts list is spelled out in detail on the Sport Performance Aviation website. Look under the WebStore heading, then Engines to see the details.

What’s special about SPA engines is displacement. While FlyCorvair concentrates on one stock displacement engine, SPA goes for increased displacement with either a 3.0 or 3.3 liter stroker. The 120-hp 3.0 uses big-bore cylinders on a set of bored-out heads and case while the 125-hp 3.3 adds a billet stroker crankshaft to the big-bore kit. Therefore, these are premium, higher-powered engines selling for considerably more than the standard displacement engines from Wynne. SPA Power Head kits are delivered unassembled.

Fly Corvair

“Impossible” is the only word to describe discussing aero conversion Corvairs and going two minutes without mentioning William Wynne. The outspoken force energizing Fly Corvair, William has made flying Corvairs his life’s calling for the past 35 years.

William Wynne continues to place all his energies on his FlyCorvair 2850cc Corvair variant, saying it is where the cost, performance and utility lines all meet.

Over the years Wynne has developed a variety of Corvair engines but he has set all of them aside in favor of one: the 110-hp, 2850cc version. “It’s the main engine I am promoting as the best combination of quality and still good value. It offers all the good tech improvements, such as Ross pistons and other advances, but doesn’t have the high-end costs of recent years. As a complete kit, with carb, ignition, starter and so on it’s $12,600. If you want it assembled it’s $13,600.”

There are advantages to this single-engine approach. Wynne has brought every step of production, except crankshaft grinding, literally under the Fly Corvair shop roof. All the machines are set to produce the 2850 engine, saving time and mistakes made reconfiguring machine tools when producing a variety of parts. Plus, Wynne conserves the profit formally made by outside shops, helping to contain his engine’s price.

“I moved as much manufacturing [as possible] in house over COVID…CNC, boring bars…I expanded the shop. Most of the 2850 is made right here in my shop. I just do it myself. What makes the engine partially affordable is not a ton of contractors. I still have some, really good machine shops, but not many, and not many components such as a gearbox. [I’m also] doing things in quantities. [It allows] tighter control and it pays off.”

Servicing a single engine is also more efficient. For example, all pistons are machined to the same weight, so single cylinder repair kits are kept boxed on the shelf for immediate delivery. Customers can buy one or six of these $299 repair kits knowing engine balance won’t change;  the parts simply need to be installed.

Wynne, a consummate storyteller and communicator, is ready to offer his expertise and shop to those wanting to assemble their own engine under his supervision. You can even run the finished engine on his test stand. He also offers a wide range of engine manuals, supporting pieces such as intake and exhaust manifolds, cowling parts and propellers, plus he gives many talks and is a genuine supporter of the builder community. He’ll be apt to tell you how the Corvair engine’s niche is offering a user-friendly, affordable, low frills path to aviation and not to overcomplicate things.

ModelDrive TypeHorsepowerWeightPrice
Azalea Aviation
Spyder 100direct100 hp210 – 215 lb wet with alternator$11,500
Spyder 120direct120 hp210 – 215 lb wet with alternator$13,500
Sport Performance Aviation LLC
3000cc (183ci)direct120 hp @ 3300 rpm225 lb w/ starter, ignition and alternator$12,395 Power Head only
3300cc (201ci)direct119 hp @ 2800 rpm / 125 hp @ 3300 rpm225 lb w/ starter, ignition and alternator$16,195 Power Head only
Fly Corvair
2850cc (174ci)direct110 hp @ 3000 rpm225 lb w/ starter, ignition and alternator$12,600 kit, $13,600 assembled


  1. The Corvair car clubs have had a number of dual meets with the Aero ‘Vair people. I’ve taken my ’67 Corvair to several of these get-together meets and it’s interesting to see what goes into an Aero ‘Vair and how well they actually fly. Corvair engines have powered everything from aircraft to motor homes and military vehicles, it’s that versatile.

  2. The Corvair aircraft engine as developed by Fly Corvair’s William Wynne provides a proven low-cost engine installation suitable for the Zenith STOL CH 750, CH 750 Cruzer and low-wing CH 650. Zenith Aircraft are designed to accommodate different engine types forward of the firewall, and are not designed “around” a specific engine. In fact, Zenith Aircraft is one of the few kit companies that doesn’t profit from telling you what engine to install in the aircraft that you build. Of course, different engines will affect performance and capability of the aircraft and some engines are less suitable than others depending on the requirements of the builder/pilot.


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