Rob Dahm's 12-Rotor Engine Made 1,515 HP. Then It Caught on Fire

It generates a bit of heat revving to 7,500 rpm.

Rob Dahm 12 Rotor On Fire

Photo by: YouTube

Christopher Smith

By: Christopher Smith

May 5, 2025 at 12:02pm ET

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The saga of the mighty 12-rotor engine continues. Rob Dahm's latest video on the monster mill focuses on more dyno tuning, and there's some good news to share. The engine is indeed a beast, posting four-figure horsepower and torque numbers with ease. Unfortunately, the big rotary set itself on fire in the process. And that's not the only setback in the project.

We've been following the progress of this project for a while now. Dahm first got the engine back in 2023; it was built several years ago but in his care, the massive 15.7-liter engine gained not one, not two, but three turbochargers. That's because the rotors are set up in three banks, giving the engine something of a V-shape to it. Before Dahm got his hands on it, the 12-rotor allegedly made 1,400 horsepower and over 800 pound-feet of torque, spinning to over 10,000 rpm in the process.

We can confirm it makes at least 1,515 hp and a very stout 1,281.4 lb-ft of torque. We say at least because things are still very much in the testing and troubleshooting phase, as evidenced by the engine catching fire after its power pull. Apparently, it generated so much heat that plastic and fiberglass shielding combusted. It ultimately reached 7,500 rpm–far short of its rumored limit.

Surprisingly, it seems the dyno team wasn't immediately prepared for such a situation. Someone is heard asking "do we have an extinguisher or something?" Moments later, a person runs into the room and starts blowing on the engine. Finally, someone jumps in with a fire extinguisher, roughly 15 seconds after the fire started. The damage was relegated to the aforementioned shielding, and after a bit of clean-up, the engine was ready for more testing.

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That's where things go from bad to worse. Apparently the engine was damaged to some degree during the high-rpm pull, but not due to the fire. A keyway was damaged, causing potential timing issues, and the engine itself became severely flooded from the power run. Back at the shop, a compression test found some rotors down considerably, likely due to damaged seals.

Dahm doesn't believe there's any detrimental damage to the engine, but it will need a full teardown to inspect the internals and replace seals. The original goal for this video was 2,000 horses; with a leaner setup (and obviously no fire) it could get there. But we'll have to wait for a future video to see if that goal is ultimately realized.