Carl Heideman
Carl Heideman
3/11/09 9:45 a.m.

The TR6 can climb from zero to 60 mph in 10 seconds. At least, that’s what Triumph claimed early in the car’s production history.

These numbers have always seemed pretty ambitious to us, as 12 to 14 seconds seems normal for TR6s in the real world. However, even if we give Triumph the benefit of the doubt, those acceleration numbers are pretty lackluster in these days of 10-second minivans. While the TR6 is a beautiful car, it can’t get by on looks and iffy claims alone. To return some street cred to the TR6, we set out to make some tried-and-true performance improvements on the car.

Our subject car is a very nice 1975 model that came to us with bone-stock running gear, including the engine, carbs and ignition. Before starting, we baselined its acceleration and horsepower figures. The car covered the zero-to-60 sprint in about 13.5 seconds—disappointing, but what we expected—while its engine produced a maximum of 74 horsepower at the rear wheels. That horsepower number was also right where we expected it to be.

Our goal was simple: We wanted to improve performance without sacrificing drivability. Additionally, we didn’t want to rebuild the engine or make overly expensive changes. To that end, we decided on some mild changes that would give our TR6 the desired performance boost while maintaining its docile street manners.

The meat of our recipe would be a ported and shaved cylinder head. To help get more air and fuel through that head, we’d also be adding a new camshaft, a pair of side-draft carburetors and a performance exhaust. Finally, we’d give the engine a good tune-up.

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