Rotary (Wankel)

2021 Engine Buyer’s Guide


Aircraft Engine Buyer's Guide 2021

American Rotary Engine

The very definition of an alternative engine. The reality is fully functional Experimental aircraft Wankel rotaries today are the work of two companies: American Rotary Engine and Auto PSRU’s (see next listing). The former builds the engines while the latter makes the propeller gearbox.

American Rotary Engine is the aviation sidebar to Atkins Rotary, a hot rod shop up to its neck in modifying and supporting Mazda Wankels for auto racers. It makes hopped-up parts and adapters for just about anything that moves and a Wankel fits in. As Mazda parts go out of production, American Rotary Engine keeps getting busier producing replacements, including such sophisticated bits as its own, upgraded rotor housing, timing covers and water pump housings.

For aviation, American Rotary Engine concentrates on the Mazda 13B engine. And while American jokes that customers all want a “500-hp engine that weighs 30 pounds,” it offers up to 200-hp, turbo normalized packages. American’s aviation-specific development is a spring-loaded pop-off valve set to 4 pounds to avoid over-boosting after descents or on go-arounds.

Big power from Chevy V-8s is the customer’s demand at AutoPSRU’s. The LS-3 engine is coupled to their SD550 gear reduction unit featuring a centrifugal clutch for reduced starter and other kickback loads.

Auto PSRU’s

Gearbox and engine-package specialist Auto PSRU’s likes to source its Mazda 13B naturally aspirated and turbo normalized engines from American Rotary Engine (see previous listing). Auto PSRU’s long-standing offering is a 200-hp firewall-forward fitment for the RV-7. Curiously, after a six-year drought, interest in Wankels picked up again in 2020, especially in the higher-powered 13B options.

Engine ModelDrive TypeHorsepowerWeightPrice
American Rotary Engine
2 rotor 13Bgeared180 hp @ 6000 rpm320 lb wet w/ alternator, starter, ECU, EFI and EI$20,000
Mazda 13Bgeared180 hp @ 7600 rpm (centrifugal clutch) 2.778:1 ratio385 lb installed, typical, complete$34,100 FF
Mazda 13B Turbo Normalizedgeared200 hp @ 7600 rpm (centrifugal clutch) 2.778:1 ratio410 lb installed, typical, complete$42,700 FF


  1. Tom, I have a 13B that I bought some years ago in anticipation of building an RV-8 and putting in rotary power. Would you be interested in buying the engine, or can you offer help and parts to finish the conversion for aircraft use? I overhauled the engine, new rotor seals, etc, and did the basic mods per Bruce Turrentine and Tracy Crook’s manuals and have boxes of the accessories. Age has caught up with me and now my son, who is is retired USAF and a captain with AA is planning on doing the RV-8 and we’re contemplating finishing the 13B mods or else parting with it and staying with a Lycoming. – Thanks, Tom Koehl

  2. for ultralights:
    > Aixro XP40 rotary engine, 294cm³ (with belt reduction drive)
    35hp (26 kW) at 6,500rpm, Torque >35 N·m from 4,500rpm
    18kg Dry weight (excl. exhaust, cooling and reduction)
    Consumption: 5 to 8 L/h (1.1 to 1.76 Imp gal/h at 5,000rpm, 2% petrol/oil premix
    Poly-V belt reduction drive (2.5:1 or 3:1)
    115-120 kg trust
    Fuel consumption: 6-7 liters /hour

  3. I’m working on a project inspired by the PJII dreamer I saw and Fun and Sun a few years back. I’m looking a t using 2 Wankles 13b’s as direct drive to ducted fans in a similar setup vs the LS5 or LS 6 with increase gearbox. That plane uses the opposite reduction gears to spin the fans at 7000 rpms from the motor running 5000prms. I don’t like the single point of failure killing both fans. it seems Wankles would be able to direct drive the fans saving weight and increasing reliability. Thoughts?
    source link


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