Torque is the twisting force an engine produces, measured in pound-feet (lb-ft); horsepower is how fast that work is done. They are linked by engine speed: horsepower equals torque times RPM divided by 5,252, which is why the two curves always cross at 5,252 RPM on a graph using these units. Torque is what you feel pulling away and towing; horsepower is what sets top-end performance.
Horsepower vs torque explained
- Torque is force times distance at the crankshaft. High torque at low engine speed makes a vehicle feel strong from a stop and when towing.
- Horsepower combines torque with speed. An engine that keeps making torque at high RPM makes more horsepower.
- The formula: HP = torque (lb-ft) x RPM / 5,252.
Diesel vs gasoline
Diesels such as the 6.7 Cummins make very high torque at low engine speed but do not rev high, so their torque figure is large relative to horsepower. Gasoline V8s such as the LS3 or 5.7 Hemi rev higher and make their horsepower further up the range. See diesel vs gas truck, 6.7 Cummins specs and LS engine specs.
Crank horsepower vs wheel horsepower (HP vs WHP)
Manufacturer ratings are crank horsepower, measured at the engine. Wheel horsepower (WHP or RWHP) is measured at the driven wheels on a chassis dynamometer, after losses through the transmission, driveshaft, differential and tires, so it is always lower. Drivetrain loss is often estimated at roughly 10 to 20 percent, but it varies with the drivetrain, the dyno and the conditions, so treat any conversion as an estimate.
Reading performance claims
- East Coast Supercharging quotes wheel figures for many kits, for example 188 whp over stock for its C7 NOVI 1500 kits and a 575 to 625 RWHP base target for its 2010-2015 Camaro NOVI 1500 kits.
- AWE lists maximum gains of 11 hp and 11 lb-ft at the wheels for its Track Edition cat-back on the 2011-2021 WRX and STI sedan.
- Fleece rates its 6.7 Cummins Cheetah turbos to support up to 700 rwhp, a capacity rather than a gain.
Compare like with like: a wheel figure and a crank figure are not the same measurement, and gains measured on one dyno will not always match another; see what is a dyno?
Adding power
For the platforms we carry parts for, the biggest gains come from forced induction; see how much horsepower does a supercharger add? and our supercharger kits by platform. Smaller gains come from an intake or a cat-back exhaust.
More guides: what does a camshaft do?.
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