What is horsepower in a car?
Horsepower is a calculation of work over time. A car engine actual only makes torque, not horsepower. Horsepower is calculated as 550ft-lbs/sec. or 33,000 ft-lbs/min. If you can maintain the engines torque to a higher rpm in makes more horsepower.
An example: an engine that makes 404 ft-lbs @5200rpms =400hp(404*5200/5252), an engine that makes 254ft-lbs. at 8250rpm(like a Ferrari) make the same 400hp(254x8250/5252).
On a dyno sheet the torque and horsepower curves will always cross at 5252rpms.
On the street it would be the same, using the example above: The 400hp@5200rpm car with 28" tire with 3.5 gear 1:1 transmission gear would do 123.8mph at 5200rpms.The other car with same tires would need 5.57 gears with a 1:1 transmission to do 123.8mph at 8250rpms(where it is rated for 400hp). They will both be putting the same amount of power to the ground. 404lb-ft x 3.5 = 254 x 5.57 =1414 ft-lbs.
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