The air-cooled Volkswagen aero conversion community shares many characteristics. Obviously they are all built from the VW Type-1 engine, even if some have been upgraded to the point where there are no original VW parts in them.
This means all VW conversions offer compellingly light weight, impressively low costs due to overwhelmingly favorable economies of scale, an upper limit of about 100 hp and a customer base interested in maximizing these characteristics. These are also well-sorted, mature engines as the conversions have been developed for decades. It’s also something of a world unto itself, including common sources of VW parts. For example, last year there was a shortage of stock magnesium VW cases and everyone was running around scrounging what they could. But that issue is now resolved and cases are available again.
Another shared characteristic is almost all VW aero engine conversions are sold as kits. This saves both the engine manufacturer and the customer money. The one outlier is the original VW aero converter and elder statesman of hot-rodded air-cooled VWs, Revmaster. They assemble and ship their engines as ready-to-run powerplants, something to keep in mind when comparing prices.
For 2024 all four VW engine shops have not made any meaningful technical changes to their engines.
AeroVee
AeroConversions, maker of the AeroVee engine, is the piston engine division of Sonex aircraft. A busy, pocket-size aircraft manufacturer producing everything from gliders to single-seat jet sportsters and government UAVs, Sonex’s original core is a series of airframes designed for air-cooled Volkswagen power. Now mature designs, there are no technical changes to the resulting AeroVee engines for 2024.
There are two AeroVee engine kits, the 80-hp 2.1-liter naturally aspirated engine along with a turbo version rated at 100 hp. A turbocharger water cooling system was introduced five years ago and is a near-universal option on the 100-hp engine thanks to its transparent-to-the-pilot electronic control. AeroVee’s laser-cut baffle system and AeroInjector carburetor are also popular, and existing AeroVee owners can upgrade to the turbo with a $4,200 kit.
Great Plains Aviation Supply
Great Plains reports good steady business and a ready supply of parts including magnesium cases that were in short supply last year. In other words, it’s all good in their corner of the VW engine world.
Great Plains offers both four- and two-cylinder VW variants, with a choice of driving from the pulley or flywheel end of the engine. They’ll also happily sell short- or long-block engine kits. Many accessories are offered, including a belt-drive propeller speed reduction unit.
Hummel Engines
Supplying Hummel Aircraft with engines is clearly the main business here, but Hummel Engines also does plenty of business building four- and mainly two-cylinder VW-based engines for the rest of the hobby. Hummel reports that after being “absolutely swamped” for three COVID-driven years, orders slowed in the last half of 2023, meaning now is a great time to order an engine.
Hummel’s offerings favor basic, lightweight, low-power builds beginning with a bare-bones 35-hp, 85-pound, two-cylinder bereft of starter or second magneto. The top Hummel is a fully optioned 85-hp four-cylinder with starter, dual ignition and alternator.
Revmaster Aviation
Easily the most experienced VW engine house with nearly 4000 engines built, Revmaster has been building hot VWs for cars and airplanes since 1959. They cater to the better equipped end of the VW market and sell their engines assembled and not as kits.
Their bread-and-butter is the R-2300 (2331cc, 142.2 cubic inches). Takeoff power is 85 hp at 3350 rpm; the continuous rating is 82 hp at 2950 rpm. Now a well-sorted combination backed by all sorts of aviation and uber high output automotive testing, the naturally aspirated R-2300 uses Revmaster’s own cylinder head and bristles with internal upgrades. These include a four-bearing crankshaft, the unique ability in the VW market to support hydraulically controlled propellers, an eight-coil/eight-spark-plug dual CDI ignition, dual 20-amp alternators and a simple, slide-type, floatless Rev-Flo carburetor.
A turbocharged version of the 2300 is finished and can be purchased but still hasn’t flown. It’s rated at 102 hp at 3200 rpm up to 12,000 feet. Call if you’re interested in taking this one airborne.
