Some say there’s no replacement for displacement; I say there’s no replacement for revs. Low-end torque is a boon, but it has nothing on a tachometer that plays the floor-is-lava with the 7,000 rpm mark. And if you own an air-cooled Porsche 911, you can now play that game with a new set of four-valve cylinder heads that are built for a mystical 12,000 rpm.
Such heads are a new offering from Swindon Powertrain, the exclusive supplier of the British Touring Car Championship’s race engines, which also appears to have had a hand in the canceled Jaguar C-X75 supercar. The heads are built to fit the Porsche M64, the family of air-cooled flat-sixes used in the final two generations of air-cooled 911, the 964 and 993. From the factory, they’re just single-overhead-cam three-valve units, or about on par with that you’d find in a minivan of the time. These are still single-cam too, but they’re a world apart from the stock engine.
For starters, they now feature four valves per cylinder, enhancing flow. They raise compression from about 11:1 according to 964UK.com to 11.5:1, with 12:1 being available if you buy the right pistons. They’re 7.7 pounds lighter than the stock heads too, which ought to improve handling.
Better still, they’re a perfect fit with the stock engine’s cam drive, oiling system, valve covers, crankcases, and even exhaust. They include an installation manual and have also been designed to accommodate a 997 GT3 intake and 718 ignition coils if you’re going the resto-mod route. If you are, Swindon Powertrain also offers power steering drive compatibility, CNC porting, a carbon fiber fan shroud, and any cam profile your heart could desire.
Of course, it’s sometimes said that Porsche‘s air-cooled engines are the most expensive way to make horsepower, and that appears to be the case here. The starting price for these heads isn’t listed on Swindon Powertrain’s website, and you know how the saying goes: If you have to ask, you can’t afford it. That said, given the price of air-cooled 911s these days, it’s probably of no consequence to their owners—especially the ones who can afford to chase every last horsepower gain.
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