Torque vs Horsepower -- how do you use it?

[RafRaf]

Diesel Tsikoteers!

What's the main difference between torque and horsepower... and what is the right way of using it?

Thanks!
RafRaf

[luckytruck]

interesado din ako dito. puro hula lang kasi ang pagkaalam ko dito.

in my own guessing game, ang pagkaalam ko is high tourque means quicker acceleration/more pulling power. tama ba yun?

last na hula... i think that horsepower is the raw ability of the engine and torque is the horsepower mated to the gear ratios of the tranny and differential to produce pulling power or acceleration.

tama ba or sablay? hehehehehehe nanghuhula lang ako dito.

andy

[explorer]

articles taken from one of ford's intranet site:....

Ever since the horseless carriage replaced the horse and buggy as everyday transportation, people have used horsepower as a measure of motor muscle for machines.

Big horsepower numbers make big headlines and many customers look closely at the number of horses under the hood when they are out shopping for a new car or truck. They figure more horsepower equals better performance, but that's not always the case. The powertrain folks have a saying: people buy horsepower, but what they really drive is torque.

Truck customers value the pulling power of torque.

Torque also improves car performance.

"Torque turns the wheels," said Barb Samardzich, former chief enginner for automatic transmissions. "Torque is a measure of energy the engine is putting out that enables you to pull your load. If you have high horsepower, but you don't have the torque, you're going to have a hard time hauling that load."

Torque is what gets you rolling in the first place and horsepower keeps you moving along. The impressive 390 hp generated by the SVT Cobra is matched by 390 foot-pound of torque, and that 500 hp of adrenaline rush in the Ford GT comes with 500 foot-pound of torque. Keep in mind that these vehicles are among the top tier of high performance production cars, and they have the numbers to prove it. A more mainstream Ford Taurus has about 200 hp and 200 foot-pound of torque.

"Low end torque (below 3,000 rpm) is what snaps you back into your seat when you take off from a stoplight," said Gary Arvan, program manager, V-8 Diesel Engines. "Torque helps you accelerate off the line faster. It has a big impact on both car and truck performance."

More often than not, car customers look only at horsepower. It's a different story altogether for truck buyers. They are almost always more tuned in to torque. The wheels on a vehicle are basically twisting, and the twisting power known as torque is especially important to truck customers.


TorqShift with 6.0 Power Stroke Diesel engine.
"Truck customers know that without good low-end torque they are going to have trouble hauling big loads," said Samardzich. "With a lot of torque people would say 'that truck really has a lot of power.' If it doesn't have enough torque, people would say 'the engine feels like it's straining.'"

The 2004 F-150 will feature a new, more powerful, 5.4-liter three-valve V-8 engine that cranks out 300 hp and a huge 365 foot-pound of torque. Both numbers mark a big improvement for the top-selling Tough Truck.

"There's been a lot of discussion about horsepower wars in the media when they should be discussing torque," said Pete Dowding, manager, Ford Modular V-8 and V-10 Engine Programs. "People are towing bigger rigs and need the torque to pull those vehicles along. Our new 5.4 can go up against larger displacement engines and we're fully competitive against them in useable torque."


2003 Ford F-350 FX4
A diesel engine can give truck customers even more low-end torque and more efficient operation to make it easier to get the job done. Two out of three Ford F-Series Super Duty trucks are equipped with Power Stroke Diesel engines. The new 6.0-liter Power Stroke features a best-in-class 325 hp and a whopping 560 foot-pound of torque.

An engine that can crank out that kind of torque needs a durable and responsive transmission to deliver that twisting power to the wheels. The new Power Stroke features the all-new TorqShift five-speed automatic to meet the demanding needs of customers and the increased demands of high torque.

"More torque equals more power and more pickup and that means more performance," said Samardzich.

[luckytruck]

medyo malapt na rin pala ang hula ko

andy

[mcjayz]

In discussions about cars, people love to get worked up about horsepower.

"My car has 200HP," grunts one.

"I changed air filters and gained 5HP," grunts another.

But really, what does horsepower mean for performance? In truth, claims like the above tell you very little about how fast a car accelerates.

First off, figures like these are a measurement of horsepower at a specific RPM. We're talking about cars engines, though, which run over a wide range of speeds. When an auto manufacturer states their engine produces 240HP at 6000RPM, it means that ONLY at 6000RPM is it capable of 240HP. At speeds above and below that, the value drops.

Furthermore, horsepower is in a sense, unimportant. Horsepower doesn't move a car. It is really a measurement of how capable the engine is of maintaining the force that really is moving the car. I'm sorry about the vagueness, I'll try to clear things up as we go on.

What does move the car? What makes it get from 0-60mph? The same thing that basic physics teaches us is required to move anything: Force.
( my share so topic, u cn see d full dtails of this in this website. http://ubermensch.org/Cars/Technical/hp-tq )

[Walter]

Horsepower sells cars.
Torque wins races.

[RafRaf]

Akala ko kasi torque is limited to pulling power (like carrying loads and stuff) and horsepower is a factor in getting speed.

So in practical terms, when I check my manual/specs... if I want to get the most speed, I should operate my ride at its max torque spec (get into the specified rpm)?

[luckytruck]

as far as i recall, someone on this board said that in order to accelerate in the most efficient manner (not waste any engine force), shifting should be done at the rpm where there is the max torque. anything above that, you are just wasting energy. tama ba yon?

andy

[xox]

i still don't get it btw, is torque like acceleration which measures speed without the weight of the car or is it more like horsepower where you have to take into consideration the weight?

I mean a 0-100 7 sec. car is as fast as a 0-100 7 sec. truck, however a 200 horsepower car should be faster than a 200 horsepower truck keeping everything else other than weight similar. Which is torque more related to? Will a 500lb-ft car be as fast as a 500lb-ft truck?

[racerx]

ako analogy ko ganito:
torque parang diesel engine while horspower parang gas. puwede mong istart from standstill on 2nd gear ang diesel while sa gas, baka mamatayan ka ng makina unless you step on the gas more and slip the clutch.

another thing to confuse you is the characteristics of the L300 gas as compared to the 2.0l engine of the adventure. mas torquey (IMO) ang sa L300 gas pero may higher top speed ang adventure. hth

[EVO-V]

ako analogy ko ganito:
torque parang diesel engine while horspower parang gas. puwede mong istart from standstill on 2nd gear ang diesel while sa gas, baka mamatayan ka ng makina unless you step on the gas more and slip the clutch.

another thing to confuse you is the characteristics of the L300 gas as compared to the 2.0l engine of the adventure. mas torquey (IMO) ang sa L300 gas pero may higher top speed ang adventure. hth

Best check the numbers on that.

The venerable 4D56 whether NA or turbo gives out max torque at 2000rpm

The turbo gives about 24 kg-m with 96ps *4500rpm if I remember correctly.

The gasoline engine of mitsu on the L300 is simply a gas guzzler with all the weight it has to haul, and I yet have to see any petrol engine from Mitsu that can get that performance at a pricepoint enough for an L300.

[RafRaf]

hmmm... on humps, I usually thift down to third (speed down to 10-15kph) and slip the clutch a bit (so as not to lug the engine) then get back to speed... hindi naman masyadong hirap ang engine ng adventure (diesel) ko. Is that ok or am I wearing of my clutch too soon?

[racerx]

afaik you should go down to 2nd at least

[wiretap_md]

H for horsepower = Honda
T for torque = Toyota

[trisky]

Ang power po ay product ng torque at angular speed.
Units for power are Hp, kW etc.
Torque units naman are in N-m, ft-lbs etc. (perpendicular force x distance ~ to create a turning effect called moment)
Units of angular speed naman po ay rad/sec, rpm etc.

Do the maths from here... hehehehe....

Ang ibig pong sabihin nito, at a certain rpm, power is directly proportional to torque, i.e., the higher the torque, the higher the power, or vice-versa, the higher the power, the higher the torque.

So if you look at torque-speed curves, you'll notice that power is not mentioned. Simply because it's the product of torque and speed at a point in the curve. If you know the torque and speed at a point, you can calculate the power requirement at that point. Just make sure your units are consistent.

Boring huh?

[ebbfolls]

I also got purdy confused about this some time ago and all the books, magazines, etc, that Ive read about it on didnt give me a clear understanding of what torque and horsepower really were. Most of them said torque was the twisting force and horsepower was the ability to do work in a given time. That made sense, but there was something that still didnt make it all fit together. So I tried figuring the formula for horsepower. HP = Torque X RPM/5252. And that's how I think I've finally figured out the basic truth about the whole thing:

Torque, as how the word is mostly used, means the twisting force, which ultimately translates to "hatak".

Horsepower simply means Torque X RPM/5252, thus if it is said that an engine has a high horsepower rating, it either means it has a lot of torque at a low rpm (e.g., large displacement diesels as used in commercial trucks or in marine application) or it is capable of very high rpm though it can only produce relatively little torque(e.g., racebikes, small displacement/high HP cars like the Honda S2000), or both(like the large displacement, high HP engines found in expensive sports cars/sedans).

So when a layman says a car is "torquey" it usually means the engine produces a lot of torque at low rpm(Low RPM Torque). (Ever notice how this characteristic is strong among diesels? Well that's because diesels are designed to breathe efficiently at lower rpm by reason of the slower burn rate of diesel fuel. It's just much harder for a diesel engine to burn a charge efficiently for a period of .005 sec, which is the time the entire power stroke takes from TDC to BDC at 6000 RPM.) In contrast, a high HP car would be relatively weak at low rpm but would suddenly feel strong at mid to high rpm(High RPM Torque). This characteristic of the engine is all a part of engine tuning(intake/exhaust design and valve timing)--which basically addresses the question: at what rpm do you want your engine to be strong at?

Low-End torque and High-End torque both have pros and cons which I need not explain further. To get the best of both worlds, engineers have come up with techniques that allow the engine to breathe equally well at all rpm's. There are 2 basic was to do this: Variable Valve Timing and Variable Intake Runners.

To conclude: "torquey" means the car is STRONG, while High HP means that the car is FAST.

[ebbfolls]

Originally posted by wiretap_md
H for horsepower = Honda
T for torque = Toyota

LOL! That's a good observation. It does hold true for the most part.

[ebbfolls]

Originally posted by luckytruck
as far as i recall, someone on this board said that in order to accelerate in the most efficient manner (not waste any engine force), shifting should be done at the rpm where there is the max torque. anything above that, you are just wasting energy. tama ba yon?

andy

That depends on what you mean by efficiently. If you mean efficient as in the quickest way to accelerate, theory dictates that you shift up ONLY at the roadspeed that will cause your next higher gear to spin the engine at the rpm slightly lower than the rpm where it is making the most TORQUE. Fpr example, if your car is running at 40 mph and the engine is spinning at say 5,500 rpm in first gear, and that 2nd gear at 40 mph vehicle speed would spin the engine at 4,200 rpm, while peak torque is found at 4,500 rpm, then yes 5,500 rpm is your most efficient shift point when shifting from 1st to 2nd. If you upshift from 1st at 30 mph, the engine would only be spinning at 4,125 rpm and would then translate to 3,150 rpm at 2nd gear, which is way below the 4,500 rpm at which max torque occurs(depending on the torque curve characteristic of the engine, this may not be too bad--but if the engine is "peaky" it would really make a big difference).

On the other hande, if you mean efficient as in frugal, then it would be best to shift at the vehicle speed that would allow the engine to spin at an rpm enough for it to make the torque required to move the car in the next higher gear. The engine is operating at its leanest at the least amount of throttle opening for a given speed and load. So, in order to be fuel efficient, one needs only to push down on the accelerator gently and shift up soon enough as to allow the engine to pull the car without need for excessive accelerator pedal pressure(which may be accompanied by knocking).

[acenie]

That depends on what you mean by efficiently. If you mean efficient as in the quickest way to accelerate, theory dictates that you shift up ONLY at the roadspeed that will cause your next higher gear to spin the engine at the rpm slightly lower than the rpm where it is making the most TORQUE. Fpr example, if your car is running at 40 mph and the engine is spinning at say 5,500 rpm in first gear, and that 2nd gear at 40 mph vehicle speed would spin the engine at 4,200 rpm, while peak torque is found at 4,500 rpm, then yes 5,500 rpm is your most efficient shift point when shifting from 1st to 2nd. If you upshift from 1st at 30 mph, the engine would only be spinning at 4,125 rpm and would then translate to 3,150 rpm at 2nd gear, which is way below the 4,500 rpm at which max torque occurs(depending on the torque curve characteristic of the engine, this may not be too bad--but if the engine is "peaky" it would really make a big difference).

On the other hande, if you mean efficient as in frugal, then it would be best to shift at the vehicle speed that would allow the engine to spin at an rpm enough for it to make the torque required to move the car in the next higher gear. The engine is operating at its leanest at the least amount of throttle opening for a given speed and load. So, in order to be fuel efficient, one needs only to push down on the accelerator gently and shift up soon enough as to allow the engine to pull the car without need for excessive accelerator pedal pressure(which may be accompanied by knocking).

Paano nyo malalaman ang MAX TORQUE? para alam mo kung shift/change gear na?

[RafRaf]

trisky, ebbfolls... learned a lot from your posts... I see the light... thank you!