Here’s the sound of a one-rotor Turbo Miata producing 155 HP.

      Rob Dahm via YouTube

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      You might have heard about Rob Dahm’s remarkable 12-rotor engine featuring three turbos. Well, this is somewhat the opposite: his single-rotor Miata, which he has been constructing and showcasing on his YouTube channel for about a year now. Dahm recently took it to the dyno, and the outcome was unexpectedly impressive. In fact, it’s so powerful that it could damage the rear differential if pushed too hard.

      This build has been one of the most engaging to follow on YouTube lately. You could spend hours watching all the one-rotor content produced thus far, but the key details are that the engine is primarily made from billet aluminum, weighing approximately 70 pounds. It’s supported by an internally wastegated Garrett GBC-22 turbo and features a 3D-printed intake manifold, as those aren't typically available.

      Dahm has been driving the single-rotor Miata across the last five episodes. Tuning it has been a challenging yet rewarding endeavor, requiring considerable effort to fine-tune the engine's performance. It currently injects a significant amount of fuel into the combustion chamber, but it's progressing.

      Upon arriving at Westech Performance, the team secured the Miata for a series of test runs. It achieved a peak output of 155 horsepower and 136 lb-ft of torque, which is impressive considering this is a completely custom-built project with minimal displacement. The one-rotor engine could potentially generate even more power once Dahm resolves the persistent fuel issue.

      Ultimately, this build isn’t completely refined yet, but it will be soon. Dahm has identified certain issues, such as boost creep from the internal wastegate that causes sudden pressure spikes up to 22 psi, potentially forcing fuel into the oil catch can. Once he adjusts the internal clearances and addresses the turbo problem, it should perform robustly.

      I have great respect for this project. I could never assemble something like this, and to be honest, who cares about the power output? A working turbo one-rotor engine is quite remarkable. The fact that it can drive a Miata down the highway is just an added bonus.

      Have a tip or question for the author? Reach out directly at caleb@thedrive.com.