Aircraft Engine Buyer's Guide 2021


AeroConversions is the piston engine division of Sonex Aircraft, LLC, a burgeoning, pocket-size aircraft manufacturer producing everything from gliders to single-seat jet sportsters and now UA’s for the government. The heart of the Sonex sporting line is a series of airframes designed for air-cooled Volkswagen power—hence the in-house AeroVee brand for the adapted Volkswagen (VW) engine line.

There are two AeroVee engine kits: the 80-hp, 2.1-liter, naturally aspirated engine and a turbo version rated at 100 hp. These kits, as do all AeroVee kits, arrive at the customer’s door as disassembled engines. You don’t pay AeroConversions a lot of money to assemble your engine but rely instead on a thorough instruction manual, other AeroConversion support and your own initiative to keep that money in your pocket.

Like most VW-based engines, the Sonex AeroVee is sold as a kit so the buyer can save some money by assembling it himself. As a result, this 2.1-liter engine delivers 80 hp for only 161 pounds and $7600, plus a bit of assembly labor.

For 2021 there are no hardware changes to the two well-developed AeroVee engines as the company focuses on strong quickbuild airframe (and engine) kit sales. The turbocharger water-cooling system introduced two years ago remains popular thanks to its transparent-to-the-pilot electronic control and is a near-universal option on the 100-hp engine. AeroVee’s laser-cut baffle system and AeroInjector carburetor are also notable sellers.

Great Plains

“Extraordinarily busy” is the word from Great Plains. Like others in the lower-cost, do-it-yourself end of aviation, it seems sequestration has been good for business. “The old guys won’t just stay in the house; they’re out in the garage building airplanes.”

This means Great Plains is keeping busy filling orders and not developing new parts, which considering Great Plains’ many decades in the VW business, isn’t an overriding concern at this point. Thus, there are no technical or pricing changes from last year to Great Plains’ wide variety of engines and options. Both four- and two-cylinder VW variants are offered, with a choice of driving from the pulley or flywheel end of the engine. All Great Plains engines are shipped as unassembled engine kits, as either short or long blocks. Many accessories are offered, including a belt-drive propeller speed reduction unit.

Hummel Engines

With Rotax now producing just one two-stroke model, the niche for suitably small and light engines has largely been filled by two-cylinder half-VW engines, among others. This has been a boon to Hummel Engines, an outfit that offers full-featured four-cylinder VW conversions but whose specialty is no-frills, very light, two-cylinder VWs. The manufacturer has been “absolutely swamped,” filling the need for Legal Eagle, Fisher 202, Ultra and, of course, Hummel aircraft engine needs. Call ahead as lead times are long with such brisk sales.

The cost savings with the essentials-only engines is amazing. Whole engine kits can be had for the price of porting and chrome valve covers on a hot Lycoming. Hummel’s offerings begin with an 85-pound, 35-hp, two-cylinder for $3350. You’ll be good at hand-propping such an engine as it has no starter. And there’s only one magneto at this weight, but you get the idea. Hummel’s line tops out at 85 hp for a fully optioned four-cylinder with starter, dual ignition and alternator for just $7400. There are no technical changes to Hummel Engines for 2021.

Revmaster Aviation

Revmaster’s bread-and-butter engine is the R-2300D direct-drive unit. Highlights are Revmaster’s own new-production cylinder heads and a fourth main bearing for maximum crankshaft support.

Easily the most experienced VW engine house, Revmaster in Hesperia, California, has been hot-rodding VW car engines since 1959 and building VW aero engines since 1968. Impressively, the original crew of Joe Horvath and Ralph Maloof are still making VW cars go very fast and developing new aero engines, so they must be doing something right.

Their bread-and-butter powerplant is the R-2300 (2331cc or 142 cubic inches) at 82 hp using 3350 takeoff rpm; the continuous rating is 2950 rpm. Clearly now a well-sorted combination, the R-2300 uses Revmaster’s own cylinder head and bristles with internal upgrades. These include a new four-bearing crankshaft, the unique ability in this market segment to support hydraulically controlled propellers, an eight-coil/eight-plug dual CDI ignition, dual 20-amp alternators and a simple, slide-type, floatless RevFlow carburetor.

A turbocharged version of the 2300 has been in development for several years and was ready for its first flight at our deadline. It’s rated at 102 hp at 3200 rpm up to 12,000 feet. Check with Revmaster for availability of this engine in 2021.

Much further in the future is an R-3000 naturally aspirated and turbo engine. Revmaster has developed what is pretty much an all-new, ultimate VW derivative in this design. Using a new case, heads and internal parts, it’s designed to make the huge step up to the 110 hp (130 hp turboed), direct-drive market, but not this year.

Finally, absolutely shelved for now is the geared (PSRU’s) version of the R-2300. Revmaster determined there isn’t enough market to justify the geared engine’s development in the current market.

Engine ModelDrive TypeHorsepowerWeightPrice
AeroConversions (Sonex)
AeroVee 2.1direct80 hp @ 3400 rpm160 lb w/ alternator, starter, carb, ignition$7600 kit
AeroVee 2.1 Turbodirect100 hp @ 3400 rpm185 lb w/ alternator, starter, carb, ignition$11,995 kit
Great Plains Aircraft Supply
1835cc front drivedirect65 hp @ 3600 rpm, 60 @ 3400 rpm continuous163 lb w/ alternator, starter, carb, Slick 4220$6239 kit
1835cc flywheel drivedirect65 hp @ 3600 rpm, 60 @ 3400 rpm continuous156.5 lb w/ alternator, starter, carb, distributor$5898 kit
1835cc reductionbelt85 hp @ 4200 rpm, 65 @ 3400 rpm continuous176.8 lb w/ alternator, starter, carb, Slick 4220$6766 kit
1915cc front drivedirect69 hp @ 3600 rpm, 65 @ 3400 rpm continuous163.2 lb w/ alternator, starter, carb, Slick 4220$6239 kit
1915cc flywheel drivedirect69 hp @ 3600 rpm, 65 @ 3400 rpm continuous156.7 lb w/ alternator, starter, carb, distributor$5898 kit
1915cc reductionbelt85 hp @ 4200 rpm, 65 @ 3400 rpm continuous177 lb w/ alternator, starter, carb, Slick 4220$6766 kit
2180cc front drivedirect76 hp @ 3600 rpm, 70 @ 3400 rpm continuous164.5 lb w/ alternator, starter, carb, Slick 4220$7070 kit
2180cc flywheel drivedirect76 hp @ 3600 rpm, 70 @ 3400 rpm continuous158 lb w/ alternator, starter, carb, distributor$6228 kit
2180cc reductionbelt103 hp @ 4200 rpm, 70 @ 3400 rpm continuous180 lb w/ alternator, starter, carb, Slick 4220$7205 kit
2276cc front drivedirect80 hp @ 3600 rpm, 76 @ 3400 rpm continuous165 lb w/ alternator, starter, carb, Slick 4220$7070 kit
2276cc flywheel drivedirect80 hp @ 3600 rpm, 76 @ 3400 rpm continuous158.5 lb w/ alternator, starter, carb, distributor$6228 kit
2276cc reductionbelt105 hp @ 4200 rpm, 72 @ 3400 rpm continuous180.5 lb w/ alternator, starter, carb, Slick 4220$7205 kit
Hummel Engines
1600ccdirect50 hp @ 3600 rpm140 lb w/ carb, Slick mag, wo/ starter or alt$4,250
1835ccdirect60 hp @ 3600 rpm145 lb w/ carb, Slick mag, wo/ starter or alt$4,450
1915ccdirect65 hp @ 3600 rpm145 lb w/ carb, Slick mag, wo/ starter or alt$4,475
2180ccdirect76 hp @ 3600 rpm147 lb w/ carb, Slick mag, wo/ starter or alt$5,825
2400ccdirect85 hp @ 3600 rpm147 lb w/ carb, Slick mag, wo/ starter or alt$6,025
Revmaster Aviation LLC
R-2300Ddirect85 hp @ 3200 rpm170 lb w/ alternator, starter, carb, dual CDI$9,725
R-2300DT Turbodirect102 hp @ 3200 rpm, to 12,000 feet190 lb w/ alternator, starter, carb, dual CDI$12,800
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Tom Wilson
Pumping avgas and waxing flight school airplanes got Tom into general aviation in 1973, but the lure of racing cars and motorcycles sent him down a motor journalism career heavy on engines and racing. Today he still writes for peanuts and flies for fun.


  1. Thanks for the question, Matt. It took some searching to reach anyone associated with Motorav during our research for the Engine Buyer’s Guide this year, and when we did the word was the Motorav aviation engine is on hold. Without engine construction or sales forecast for 2021 Motorav was thus dropped from our Buyer’s Guide. Of course we will list them should they return to the aviation market next year or later. –tw

  2. I currently own a water cooled 460 Ford. Weight is about 750ilbs. I can use aluminum heads and such and drop a hundred pounds and get the horsepower up to around 750 reliable. Was thinking of a single place pusher type with canard wing. Have you any info on converting these monsters for aircraft use ?

    • There have been 429/460 Ford aviation conversions by Fred Geschwender, but these have not been available for many years (decades?). Some of these engines were retrofitted to crop dusters but we’re not so sure what their record was. The “385 Series” Ford big-blocks lend themselves to huge displacements because they were originally designed to swing a long enough stroke to make 525 cubic inches by Ford, but the big block era ended before things got that big. If I were to use such a heavy engine I would go for displacement. They seem to be pretty happy at 514 cubic inches. But… this is a fantastically huge effort to convert an old monster big block into a reliable aviation engine.. The engine is the easier task, the Herculean effort is in the gearbox (PSRU Propeller Speed Reduction Unit) needed to slow the approximately 3200 rpm crankshaft speed to a workable 2600 rpm or slower propeller speed.. Getting a PSRU sorted out to handle the huge harmonics and other forces involved takes big companies years, and they have all sorts of money and tools. You’d be much better off simply hooking up a Lyc 540 or big Continental. If you’re a die hard machinest with very deep pockets, an appetite for trying and trying again, can find an old Geschwender gearbox to start with and have an airframe ready to accept nearly 1000 lbs in the engine compartment then maybe you could give it a try if you wanted a hero-class challenge. But you’d still be way ahead with a big Lyc or Conti.


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