Torque Rules! Horsepower is King!

Eternal gearhead debate rages here!

Joe Hollingsworth / autoMedia.com

Want to start an argument with a gearhead? Say that horsepower is more important than torque. Or that torque is more important than horsepower. The resulting fact-free emotionalism, random shouting, and absence of listening will be rivaled by little this side of "discussions" regarding Roe v. Wade. To paraphrase the great philosopher Jeff Foxworthy: "If you can argue about torque and horsepower for more than an hour, you might be a gearhead."

"If you can argue about torque and horsepower for more than an hour, you might be a gearhead." Often, the most passionate cannot define "torque." Nor can they accurately quote the scary math formulas for determining horsepower much less describe its origins. Here, we aspire to remove you from the vast unwashed.

Definitions

TORQUE is a twisting force that does not require motion. In the case of vehicle engines, it is the force of combustion pressing through pistons, connecting rods, and crankshaft to turn the flywheel.

HORSEPOWER is a measure of work and power created as a marketing ploy by inventor James Watt around 1775 to promote his newfangled steam engine. Textbooks define WORK as force multiplied by distance, and POWER as work divided by time. To cut the physics lesson short, here's the math formula: engine revolutions per minute (rpm) multiplied by torque at that engine speed, divided by the constant of 5252. Or RPM x TORQUE / 5252 = HP

For vehicle engines, torque is MEASURED by a dynamometer. Horsepower is CALCULATED (often by the dynamometer's software). You can tell if your ciphering (or the dyno's software) is correct if torque equals horsepower at 5252 rpm.

Peak Performance

Carmakers report PEAK torque (in pound-feet) and horsepower along with the engine speed at which those peaks occur. The torque peak indicates where the engine is pulling its strongest. The horsepower peak indicates where torque is dropping like a rock: Increasing rpm can no longer offset falling torque in the math formula. A dyno chart shows the shape of the torque curve: Ideal is a torque curve that quickly rises to near its peak and is flat as eastern Colorado after that.

For drivers, torque is FELT as punch-in-the-back acceleration, while horsepower is OBSERVED by such things as quarter-mile times or headlights disappearing in the rearview mirror.

It All Depends

To those who say "torque rules," ask if they'd like to drive a vehicle with more than 900 pound-feet of torque, and then point them toward a 250-horse farm tractor. Tell not to be frightened by the tractor's 26-mph top speed and 2,200-rpm redline.