The team at Gooichi Motors are developing a M120 V-12 swap kit.
The Mazda RX-7 community knows its way around an engine swap. For decades now, we’ve watched Wankel Rotary engines ripped from the fronts of these cars, replaced by old-school small blocks or big-turbo 2JZs. While there’s nothing wrong plugging a well-proven engine in place of a finicky whirlygig, the team at Gooichi Motors have just changed the game. The shop stuffed a built Mercedes M120 V-12 engine into their beautiful FD RX-7 for SEMA.
The Mercedes-Benz M120 V-12 engine debuted inside the W140 S-Class back in 1991. The naturally-aspirated 6.0-liter engine provided 402 hp and 428 lb-ft of torque, though power would dip to 389 hp for the 1993-1999 model years. The engine also served as the building blocks of the M297 V-12, which powered the Mercedes-Benz CLK GTR in the FIA GT Championship during that era. That said, the M120 is best known to enthusiasts thanks to its role in the Pagani Zonda platform, where it was utilized in 6.0, 7.0, and 7.3-liter displacements. With some help from the Italians, the Mercedes-Benz V-12 sounds incredible when running at full tilt.
Owners of M120-powered cars have turned to getting custom exhausts made to help bring some of that aural character out of their luxury vehicles, which is exactly how Gooichi Motors got involved with this engine to begin with. A customer came to the shop looking for custom header work, and so the team purchased an M120 out of a Miami junkyard to do some development with. As the team tried to prepare for SEMA Show 2022, the idea of stuffing that engine into their SEMA Show veteran RX-7 came to the forefront. The car was already familiar with non-rotary power, as it featured a turbocharged LS V-8 during its last trip to SEMA. Before that V-8 was installed, the team had actually intended to utilize a V-10 sourced from a Dodge Viper.
Mating the M120 to the FD’s chassis forced the team at Gooichi Motors into tons of custom work. All of the engine accessories were pieced together by the time, the mounts and wiring harness setup were custom built. A dry-sump oiling system has been fitted to make the engine more compact. The heads were also ported, the valves being worked to gain a bit of extra performance. There are also some seriously aggressive camshafts installed to emulate that Zonda character. You might also notice the velocity stacks made out of Hayabusa throttle bodies sitting atop the motor, which really gives the engine a signature look. The engine itself runs on ethanol, but is expected to make anywhere between 850 and 1000 horsepower. It should also rev to 9000 RPM.
Other highlights include a six-speed sequential gearbox, Wilwood brakes front and rear, custom Fifteen52-inspired wheels, Proxes RR tires, and KW Variant 3 coilovers. A new widebody LTO kit by Kyza provides some visual flair. The team didn’t get the car back from the body shop in time to get it running right before the SEMA Show, but they expect to have it hitting the street within three months or so. We can’t wait to hear how this thing sounds when it opens up in all of its naturally aspirated glory. The team is also planning on putting a swap kit together for various platforms, because who among us doesn’t need more V-12s running around?
Keyword: This FD Mazda RX-7 Packs a 6.0-Liter Mercedes V-12