Insanity is a BMW M3 powertrain in a Triumph TR6

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TR6 M3 engine swap Kyle Smith

Engine swaps are the ultimate way to realize automotive what-could-have-beens. Ford small-block in a small British roadster—poof—Shelby Cobra. Yanking the Chevy 216 inline-six in favor of the sturdy 235 in your Advance Design pickup? Nice factory-fit upgrade. What about going completely off the rails, though? That is where you end up with a BMW M3 powertrain in a Triumph TR6.

While perusing a cruise night in my Corvair, I came upon a Triumph TR6 with the hood up. Not a wild scenario for those who believe stereotypes about British cars, but since the hood was up and the car wore a set of massive 17-inch wheels, I was curious what might be going on under there. Boy, was I surprised.

Tucked snugly between the wheel wells was an S50 inline-six yanked from an E36 BMW M3 from the 1990s. The 240-hp 3.0-liter mill features an iron block and aluminum head, a big step up from the 112-hp inline-six that resided in this engine bay from the factory.

TR6 engine swap
Kyle Smith
TR6 engine swap
Kyle Smith

To call this engine compartment “clean” is an absolute understatement. The presentation was flawless. The owner walked over after he saw me gawking at the car for a bit. He said that the original builder of this hot rod wanted the swap to look like a factory fit. I say he succeeded. I was particularly impressed with how much room the radiator and fan had—this is not 10 pounds in a 5 pound bag. It looks organized. Neat.

The frame is said to be strengthened and braced, which is likely a very welcome upgrade. The TR6 was known to be a flexi-flyer when it was new, and now we’re 50 years on and it’s packing 150-percent more power. A five-speed manual trans is bolted to the back of the inline six, though the current owner says a six-speed would be nice for highway driving. Four-wheel disc brakes take up residence behind the giant-looking 17-inch Minilite-style wheels.

I am all about this engine swap. It seems like a really cool way to have an overpowered British roadster—without losing the inline-six burble that makes some of the great Brits great. (I can practically hear an Austin Healey 3000 right now.) Are there other ways to inject modern power into a classic roadster? Certainly. In fact the LS-series engines—that’s right, you thought you would make it through an article about engine swaps without hearing those two letters?—is lighter and more powerful, but just doesn’t seem right in this case. Or does it? Let me know your thoughts in the Hagerty Forums below.

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