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Turbo = HP or lbs.ft??

7486 Views 18 Replies 11 Participants Last post by  bbtowns
If anybody can help a gearhead who actually knows very little about gears, I got somethin' bugging me. Just saw a car commercial that trumped a turbo charger as adding torque (It was an MB diesel). Question from the less than mechanically competent: Doesn't a turbo, whether bike or car, only kick in at high rpm? And if so, isn't that the definition of bhp? I concede I may be completely wrong here but I've never heard of anybody adding a turbo to any engine to increase TORQUE. Wish I knew a good engineer...
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I think the formula is torque x rpm /5252 = HP. Or HP / rpm x 5252, which is why the formulas always cross at 5252. Others here have said it, if you make more HP, you will make more torque at that particular RPM, it may or may not change the HP you are making at the peak torque RPM, which would affect your peak torque number. In plainer language, trading low RPM HP for high RPM horsepower will typically lower peak torque, but you'd need to chart it to be sure. This is why you'll often find a Harley making 65 hp at 4K has higher torque than a 600cc sportbike making 100 hp at 11K (about 85 vs. 48 ft. lbs).
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