Rob Dahm has fitted 13 rotors to a first-generation Mazda MX-5, and the car drives. The build is on display at Haltech's booth in the Central Hall for the full run of the 2026 SEMA Show in Las Vegas, which takes place November 3 to 6.
Dahm, known for squeezing ever more outlandish engines into early MX-5 chassis, was asked by Haltech, the engine management company sponsoring the build, to bring something to its SEMA stand. He decided one rotor, or even twelve, was not enough.
Only one of the two rotary engines drives the car
The headline number is misleading on purpose. The huge 12-rotor engine mounted where a normal motor would sit does not power the car at all. Propulsion comes from a separate single-rotor engine fitted with a Garrett GBC22 turbocharger, while the 12-rotor sits on top purely for show.
Dahm's team left the wiring, fuel lines and accessories in place on the 12-rotor so it looks fully functional, but it is not connected to the drivetrain. The aim was to make onlookers wonder how any of it works rather than spot an obviously missing part. The 12-rotor engine carries a claimed output of 4,500 horsepower.
That matters because the 13-rotor count describes the whole exhibit, not the drivetrain. Anyone quoting 4,500 hp as the Miata's power is quoting the display engine, not the single-rotor unit turning the wheels.
Custom mounts and three turbochargers in a tiny bay
Fitting both engines into a Miata engine bay meant building mounts from scratch, triangulated into the chassis to resist side-to-side wobble and a teeter-totter motion caused by the weight distribution.
Turbochargers, intake manifolds and fuel rails had to be refitted in a set order, partly because some parts helped brace others against the chassis. Three turbochargers went onto the combined setup, adding roughly 70 pounds each on top of an already overloaded front end.
The team reused components from earlier Dahm projects, including labelled wiring harnesses from past builds, because rebuilding everything from zero in the time available was not realistic.
Getting it running, and getting it loaded
Before the car could run, it had to roll, and the team treated that milestone as a test in itself. Loading it into a trailer brought its own crisis, with the team weighing ground clearance against a steep ramp while the rear end slid sideways under the shifted weight. Careful measurements and a willingness to risk scraping the undercarriage got it aboard.
Dahm's team confirmed the engine fires up and the car moves under its own power, even though the 12-rotor on top never needs to.
The build follows a run of engine swaps at this year's SEMA, including two Porsche 911s fitted with V8s. For Dahm, the 13-rotor Miata is less a lap-time proposition than a booth attraction built to stop traffic, and on that measure the two-engine layout does its job.
