The BMW M3/M4 is a legend that has gone through multiple engine configurations over the years. The original 1980s E30 M3’s N/A had an inline-four. The E36 and E46 that came after it relies on also-N/A astraight-sixes. Then came the atmospheric V8 of the E9X and, finally, the twin-turbo straight-sixes of the previous and current M3/M4 iterations. Well, this ex-gen M4 introduces the breed to a different type of internal combustion engine altogether. The Bimmer throws a three-rotor Wankel under the hood, seeking to dominate the drag strip and the streets alike.
Built by Cody McManus of New Jersey, known for his Rowdy’s Garage label, this unapollogetic F82 M4 has been in the making for at least two years now. For one, I first wrote about it back in September 2020 (you can Google “M4 Rowdy Rotary” to find it). That’s when digital artist Khyzyl Saleem (aka The Kyza) released a set of renderings previewing the project.
As Cody explains in the comments section of a recent Instagram post, there are still some steps to be made before we can all enjoy the voice of the Mazda 20B three-rotor that sits where you’d expect to find a twin-turbo 3.0L S58 L6. Actually, the 1,962 cc unit (the common Mazda design involves a 654 cc displacement per rotor, multiplied by three for this application) saves quite a bit of weight and space in the engine bay—we’ll get back to the scale footprint below.
However, the builder recently made an effort to update the JDM-powered Bavarian coupe to a static show car status, hence some of the images in the gallery below. The Rowdy’s Garage rotary M4 was displayed at least weekend’s Formula Drift event in New Jersey, apparently going from a collection of parts to the said form in just one week.
Bridgeported Mazda 20B with billet bits
The brilliant madman also shared some details about the guts of the thing on Instagram. And, as he explains, simply painting/polishing a 20B borrowed from an early 1990s Mazda Eunos Cosmo wouldn’t cut it (quarter-mile goals, remember?). Instead, “pretty much every part has been modified or completely replaced when It comes down to it”.
So, we’re looking at billet eccentric shaft, billet plates, billet dry-sump pan and a semi peripheral/bridgeport setup. To deliver an oversimplified explanation, the latter is a race-spec building technique that increases the intake port timing, while using a bridge to sustain the corner seal of such Wankels, hence the name.
The rotors and housings are not billet pieces, but rather modified units. And here’s Cody’s logic: “[the said modded parts] have proven to handle well over 2,000 hp. And, frankly, there’s just not enough r&d into billet rotors yet to really justify it in a street vehicle. If the car was only going to see a 1/4 A-to-B drag racing pass then that’s a whole different story to experiment with,“
So, yes, you can expect this M4 to pack four-digit output. For that, the Mazda engine (btw, drifter Mad Mike is building a five-rotor!) works with a super-sized Comp turbocharger: turbo size is a 91106, the inlet is 6-inch, exhaust is 4.5-5-inch depending on flange choice, and turbo inlet/compressor outlet are 3.5-inch.
The drag/street spec
Firepower aside, the BMW sheds weight by using carbon body panels. And, in case you’re wondering, that U-shaped brace in the engine bay had only been aided by custom parts, but it’s a factory bit.
The M4 is lowered on custom wheels, while using drag slicks at the back. The final setup should see the vehicle sporting skinny front wheels for the track and meaty unit on the street. The parachute hanging out the back? Once again, serious drag strip intentions.
Oh, and if you wish this build becomes operational by the end of the year, you’re not alone—making brap-brap noises (here’s Liberty Walk’s four-rotor R35 GT-R) in your head right now? Also not alone.
