Under the Hood: What is Torque? What is Horsepower?

Under the Hood: What is Torque? What is Horsepower?

Automakers are always looking for an edge over the competition. Any spec-sheet advantage, no matter how insignificant, is fair game. Engine output is often something they brag about. One vehicle may have more horsepower but a competing car could offer more torque. What’s the difference between these two measurements? What do they mean? Surprisingly these terms are totally different but related.

Some vehicles are built to extremes; the dearly departed Honda S2000 sports car, which went out of production a few years ago, is a perfect example. Like the blade of a samurai sword this open-air two-door was sharp and purposeful.


Early models were powered by a screaming 2.0-liter four-cylinder that put out a monstrous 240 horsepower. What made that figure so jaw-dropping is that the engine did it without any assistance; there was no turbo or supercharger to be found under the hood. It was more natural than a flock of unkempt vegan hippies nakedly prancing around the forest during a rainstorm; it just revved and revved, topping out at 9000 RPM. Of course this extreme engine strategy came at a price. There were only 153 lb-ft of torque to play with, barely more than a tricycle-riding grandmother could provide.

2013 Ram 3500 Heavy Duty

Honda’s S2000 was the automotive equivalent of a hummingbird; always buzzing at redline, howling like a banshee. At the opposite end of the spectrum is the Ram 3500 pickup truck. Buyers can opt for a 6.7-liter Cummins diesel that puts out 350 horsepower with up to 660 lb-ft of torque. That’s enough twisting force to power an industrial revolution.

2013 Ram Heavy Duty 6.7-liter I-6 Cummins Diesel with 6-speed ma


Speaking of that pivotal moment in history, one man played a huge role in helping develop the world we live in today. Scottish inventor James Watt can be credited with kick-starting the industrial revolution in the second-half of the 1700s. He vastly improved the steam engine, which made it both more efficient and effective. He also invented something else.

James-WattAlan Falkowski, a Chief Engineer at Chrysler and someone who’s worked on a number of different engine programs over the years including the late-model Hemi and Pentastar V6 said Watt came up with an important term we use every day: horsepower.

“Essentially he wanted to have an equivalent term his customers could relate to,” said Falkowski. The expression was designed to make the nebulous idea of work relevant and easily understood. For example “I’ve got a steam engine that will do the work of two horses,” Falkowski said; that’s a lot easier to wrap your 18th-century head around than saying it delivers 66,000 pound-feet (lb-ft) per minute. Because really, what the heck does that mean anyway?


Good question. “Torque is kind of like a force,” said Steve Russ, Technical Leader with Ford Motor Company Engine Engineering. “Now power is essentially the rate at which we’re able to do that amount of work,” he said.

Falkowski gave a great example of this. If a person walks up 10 steps they’ve done a certain amount of work, but “The rate at which [they move] is power,” he said. Running up a flight of stairs in five seconds opposed to 10 seconds takes twice as much power. In other words, “The ability to do work quickly is power,” he said.

Another example of torque is trying to slide a piece of furniture across carpeting. If someone is pushing on a couch as hard as they can and it doesn’t move they’re applying a certain force.  If they can slide the couch slowly across the rug they’ve done work; doing it faster takes more power.


Horsepower and torque are related because “Horsepower is derived from torque,” Russ said. “In an engine the torque that we measure is the function of engine RPM.”


“The power that the engine produces is the torque times the engine speed,” Falkowski said. The formula for calculating horsepower is fairly simple. It’s the lb-ft of torque provided multiplied by the RPM (revolutions per minute) it’s delivered at, divided by 5,252. If an engine puts out 100 lb-ft of torque at 1,000 RPM it has about 19 horsepower.


The difference between power and force is also fairly simple. “You need low-speed torque if you’re towing [or] driving up a hill,” but, “For fast zero-to-60 times you need you need high peak power,” Russ said.

Generally diesels can’t zip from zero to 60 very quickly because they can’t rev as high as gasoline engines, but, “They can tow massive amounts,” Russ said. He also added that peak power directly relates to zero-to-60 times.

“[For] faster acceleration go with what produces the highest peak power,” Falkowski said, noting that “It’s always power at any given instance that is going to accelerate the vehicle.”

Audi Q7 V12 TDI/Technik

This is why the Honda S2000 can rip from zero to 60 miles an hour in about six seconds and why the Ram 3500 can tow in excess of 18,000 pounds when properly equipped. That’s the stark difference between horsepower and torque.

Transmissions help maximize an engine’s output. The various gears inside them are designed to multiply torque at different speeds. Tractor trailers for instance are powered by large diesel engines that deliver mountains of torque but, “Those things don’t have thousands of horsepower,” Falkowski said. Making up for that, and allowing them to tow huge and heavy trailers, they’re equipped with a dozen or more gears.

So, horsepower and torque are directly related. Horsepower is derived from the torque an engine delivers and is a function of RPM. Torque is essentially a force and power is the ability to do work; doing the same amount of work in a shorter amount of time takes more power. A car that can zip from a standstill to a mile a minute in just three seconds needs a lot more power than one that accomplishes the same task in 13 seconds.

  • MistyGreen

    Solid. I’ve been wondering about this for a while.

  • José Francisco

    Excellent! When the European small cars began to arrive to Honduras inthe early fifties years: Hillman, Morris, Escort, Anglia, Renault, Taunus, Fiat, etc., with engines of 1000 cc or less, we said that those cars were “impulse cars”.

« Back

AutoGuide.com’s Monthly Overlay Newsletter Signup – By subscribing to our email newsletter, Entrants are eligible to win one (1) Amazon.com Gift Card (value of $100.00 USD). One (1) winner will be chosen every month at random and contacted by VerticalScope Inc.’s staff. *Amazon.com is not a sponsor of this promotion. Except as required by law, Amazon.com Gift Cards ("GCs") cannot be transferred for value or redeemed for cash. GCs may be used only for purchases of eligible goods at Amazon.com or certain of its affiliated websites. For complete terms and conditions, see www.amazon.com/gc-legal. GCs are issued by ACI Gift Cards, Inc., a Washington corporation. All Amazon ®, ™ & © are IP of Amazon.com, Inc. or its affiliates. No expiration date or service fees.


2. PRIZE: One (1) Winner will be randomly selected every month to each receive: one (1) $100.00 Amazon.com Gift Card (the “Prize Supplier”). Total approximate retail value of all prizes is approximately $100.00 USD. Prizes are not transferable and no cash or prize substitution is allowed. Prize package is awarded "as is" with no warranty or guarantee, either express or implied.

3. ELIGIBILITY: From the time of entry through the final date of prize fulfillment, each contest entrant and selected entrant must be a permanent lawful citizen and resident residing in the 50 United States or the District of Columbia or in Canada, and be twenty one (21) years of age or older. VOID IN PUERTO RICO, THE U.S. VIRGIN ISLANDS, IN ALL FOREIGN COUNTRIES OUTSIDE OF THE UNITED STATES, AND ALL OTHER U.S. TERRITORIES OR CANADA AND POSSESSIONS AND WHERE PROHIBITED OR RESTRICTED BY LAW. Employees, officers, directors, agents and representatives, of the Sponsor and the Prize Supplier and each of their respective parent companies, affiliates, subsidiaries, advertising and promotion agencies, promotion partners and any entity involved in the development, production, implementation, administration or fulfillment of this Sweepstakes, and the immediate family members (e.g., spouse, mother, father, sister, brother, uncle, aunt, nephew, niece, grandparent, in-law, daughter and son, regardless of where they live) and persons living in the same household (whether or not related) of such individuals are not eligible to participate or win. Only one selected entrant per household. All decisions of the Sponsor with respect to this sweepstakes are final. The Sponsor shall have the right at any time to require proof of identity and failure to provide such proof may result in disqualification from the Sweepstakes.

4. ENTER BY INTERNET: You may enter this sweepstakes via the Internet by logging onto AutoGuide.com and subscribing to our email newsletter via the pop-up overlay.

5. SELECTION OF WINNER: One (1) Entrant will be selected by random selection who have subscribed to our email newsletter. The winner may be announced publicly on AutoGuide.com and will be contacted by VerticalScope Inc.’s staff. The winner will be required to provide a mailing address (that is not a P.O. box) to receive the prize which will be shipped free of charge.

6. ODDS OF WINNING: Odds of winning a prize are determined by the total number of eligible entries received.

7. RESTRICTIONS: The prize package consists of one (1) Amazon.com Gift Card with an approximate value of $100.00 USD. If prize cannot be awarded due to circumstances beyond the control of the Sponsor or Prize Supplier, no substitute prize will be awarded due to the unique nature of the prize. Sponsor and Prize Supplier shall not be liable to the winner or any person claiming through winner for failure to supply the prize or any part thereof, by reason of any acts of God, any action(s), regulation(s), order(s) or request(s) by any governmental or quasi-governmental entity (whether or not the action(s), regulations(s), order(s) or request(s) prove(s) to be invalid), equipment failure, utility failure, internet failure, terrorist acts, threatened terrorist acts, air raid, blackout, act of public enemy, earthquake, war (declared or undeclared), fire, flood, epidemic, explosion, unusually severe weather, hurricane, embargo, labor dispute or strike (whether legal or illegal) labor or material shortage, transportation interruption of any kind, work slow-down, civil disturbance, insurrection, riot, or any other cause beyond Sponsor's or Prize Supplier's control (collectively, "Force Majeure Event"). Sponsor shall not be responsible for any cancellations, delays, diversions or substitutions or any act or omissions whatsoever by the performers/events, other transportation companies or any other persons providing any of these services and accommodations to passengers including any results thereof such as changes in services or accommodations necessitated by same.

8. CONDITIONS: By entering the Sweepstakes, entrants agree to be bound by the Official Rules, Terms and Conditions and that Sponsor has the irrevocable right to use in perpetuity entrants' names, user names, likenesses, photographs, voices, home mailing address, biographical and prize information, and entry materials, without notice to entrants and without compensation or obligation, in any and all media now or hereafter known throughout the world, in any manner whatsoever, to advertise and promote Sponsor, its products and services, the Sweepstakes, and for any other purpose except where prohibited by law. Entrant waives the right to assert as a cost of winning a prize any and all costs of verification and redemption or travel to redeem said prize and any liability which might arise from redeeming or seeking to redeem said prize. Sponsor is not responsible for fraudulent calls or emails made to entrants not by the Sponsor. If the Sweepstakes is not capable of running as planned by reason of damage by computer viruses, worms or bugs, tampering, unauthorized intervention, fraud, technical limitations or failures, any Force Majeure Event or any other cause which, in the sole opinion of Sponsor, could corrupt, compromise, undermine or otherwise affect the administration, security, fairness, integrity, viability or proper conduct of the Sweepstakes, Sponsor reserves the right, in its sole and absolute discretion, to cancel, terminate, modify or suspend all or any part of the Sweepstakes, and to select a winner from among all eligible entries received by Sponsor up until the time of such cancellation, termination, modification or suspension, as applicable. Sponsor reserves the right in its sole discretion to disqualify any individual that (i) tampers or attempts to tamper with the entry process or the operations of this Sweepstakes in any manner, (ii) violates the Official Rules, Terms and Conditions or (iii) acts in an unsportsmanlike or disruptive manner, or with intent to annoy, abuse, threaten or harass any other person. CAUTION: ANY ATTEMPT BY AN ENTRANT OR ANY OTHER INDIVIDUAL TO DELIBERATELY DAMAGE OR UNDERMINE THE LEGITIMATE OPERATION OF THIS SWEEPSTAKES IS A VIOLATION OF CRIMINAL AND CIVIL LAWS. SHOULD SUCH AN ATTEMPT BE MADE, SPONSOR RESERVES THE RIGHT TO SEEK CIVIL AND/OR CRIMINAL PROSECUTION AND/OR DAMAGES FROM ANY SUCH PERSON TO THE FULLEST EXTENT PERMITTED BY LAW. Any expenses and receipt and use of the prize and federal, state and local taxes and fees applicable in connection with the prize awarded are the sole responsibility of the winner. An IRS Form 1099 will be issued in the name of the winner for the actual value of the prize received. This Sweepstakes is subject to all federal, state and local laws of the United States. VOID WHERE PROHIBITED. Sponsor, Prize Supplier, and their respective officers, directors, parent companies, affiliates, subsidiaries and advertising and promotion agencies, employees, representatives and agents are not responsible for and shall not be liable for (i) any injuries, losses or damages of any kind caused by a prize resulting from acceptance, possession or usage of the prize, or (ii) printing, distribution or production errors. Sponsor or its affiliates may rescind any promotion found to contain such errors without liability at its or their sole discretion.

9. SPONSOR: The Sponsor of this contest is VerticalScope Inc. (the owner and operator of AutoGuide.com), 111 Peter Street, Suite 700, Toronto, Ontario, M5V 2H1.

Subscribe to our email newsletter and automatically be entered to win.
*Restrictions apply. See offer for details

Get Breaking Automotive News, Reviews and Video in your Facebook Feed!

Already Liked