YouTuber Turns A Miata Into A Self-Propelled Stand For His 13-Rotor Engine
Rob Dahm’s turbocharged one-rotor Miata was already strange enough to earn a spot at Haltech’s SEMA booth, so he could have simply loaded it up and called the job done. He had just rebuilt its engine, too, after warped apex seals dropped compression to 60 PSI and cut highway fuel economy from about 30 mpg to almost 10. With a Vegas race on his calendar and a Monday drop-off ahead of 2026 SEMA’s Tuesday opening, Dahm still decided one rotor Miata with a gas guzzler tax wasn’t enough.
From 155 Hp To 1,515 Hp In One Garage
Dahm’s one-rotor Miata uses a nearly all-billet engine that weighs about 70 lbs and breathes through a Garrett GBC22 turbo. It made 155 hp and 136 lb-ft on the dyno in April, a healthy result from such a tiny engine.
The 12-rotor is a 15.7-liter, triple-turbo one-off built by Tyson Garvin. It made 1,515 hp and 1,281 lb-ft on the dyno before catching fire, because subtlety has never been part of this story.
That gives the big engine nearly 10 times the power of the little one. Dahm also puts it at about 900 lbs, making it close to 13 times heavier, so asking one to carry the other would be a terrible idea.
This Miata Really Is A Self-Propelled Engine Stand For The 12 Rotor Engine
The single-rotor engine still does all the driving, while the 12-rotor sits on top for display with no connection to the drivetrain. That makes this a pair of separate engines rather than one 13-rotor unit, even though the Miata now carries 13 rotors and four turbos.
Custom mounts triangulated into the chassis stop the big engine from wobbling or rocking like a teeter-totter. Dahm wasn’t chasing praise for the fabrication, saying he just wanted people to see that it wasn’t falling over.
Wiring, fuel lines, and accessories stayed on the 12-rotor so onlookers would wonder how it works. The three big turbos add about 70 lbs each, which helps explain why the front end rides on its bump stops.
Dahm floated gearing the 12-rotor through the one-rotor’s drivetrain, but his crew gave that plan about two seconds to live. One YouTube viewer summed up the finished car perfectly: “You turned a Miata into a self-propelled engine stand. Sounds about right for SEMA builds.”
No Rear Grip Turned The Trailer Ramp Into A Fight
The Miata rolled so easily by hand that Dahm said it moved better than his three-rotor car. On its first drive, he finished a short lap despite an oil hose smoking against a turbo, and his funniest complaint was that the dirty windshield hurt his view more than the giant engine.
With almost no weight over the rear wheels, the back end slid sideways on the trailer ramp. The crew rotated the exhaust stack down to clear the roof, and Dahm tried again with more speed.
The car went on display at Haltech’s Central Hall booth for the 2026 SEMA show. Dahm says the 12-rotor up top can still run, so this ridiculous Miata could technically get worse.
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