Convert torque and RPM into horsepower.
Horsepower and torque are related through engine speed: HP = Torque (lb-ft) × RPM ÷ 5252. The constant 5252 comes from the definition of a horsepower in terms of foot-pounds per minute.
This is why torque and horsepower curves always cross at exactly 5252 RPM on a dyno chart — below that RPM, torque is numerically higher than horsepower; above it, horsepower overtakes torque.
Torque describes rotational force directly; horsepower describes the rate of doing work — an engine can have high torque but modest horsepower if it doesn't rev high, or vice versa.
300 lb-ft of torque at 3,000 RPM produces 300 × 3000 ÷ 5252 ≈ 171.4 horsepower.
It's a mathematical consequence of the formula's constant, not a property of any specific engine — at RPM = 5252, torque and horsepower are always numerically equal regardless of the engine.
Torque, generally — it's the twisting force that gets a heavy load moving from a stop, which is why diesel trucks are tuned for high torque at low RPM.
Horsepower, since it reflects sustained power output at higher RPM, which is what overcomes aerodynamic drag at speed.