The Mazda Miata is beloved for being tiny and light, a combination of qualities most modern automakers seem to avoid like the plague. It’s never been the fastest car, but who really needs that? It’s more of a slow-car-fast deal, and every method of upping the power always seems to add weight in equal measure. Unless, apparently, you’re rotary wizard Rob Dahm: then you can slap a turbocharged single-rotor Wankel in there, and add power while actually cutting weight.
Dahm’s latest project is to swap an NA Miata’s four-cylinder out for a compact rotary engine. But unlike other rotary swaps, that usually use a 13b dual-rotor out of an RX-7, Dahm is using just a single rotor for his Miata. This comes with its own challenges around simply putting the engine together, but it also ends up with an engine block that weighs just 64 pounds, or less than half the shortblock weight of the engine it’s replacing. Yet Dahm claims, with a properly-sized turbocharger, this build could double the Miata’s factory horsepower.
The engine block weighs only 64 pounds
This video is just the first in the build series, but it’s already more progress than many ambitious swaps ever make. The Miata’s transmission has been cut up and welded to a rotary bellhousing, and the single rotor mill is physically inside the car’s body. Surely not for the final time, as it’s missing little niceties like “engine mounts,” but it’s in there all the same. The rest is just wiring and pipes, and that’s easy, right?
If Dahm is correct about the eventual power and weight of this engine, he could have a truly incredible Miata on his hands by the end of the build. It would be more powerful than any Miata built by Mazda, but still light enough to sit with the stock cars, and not so overwhelmingly powerful to entirely change the beloved driving dynamics of the NA. We’ll have to keep our eyes peeled on the build to see how it pans out.
