Torque vs Horsepower

[kevinthenerd]

Originally posted by: Demon-Xanth

Originally posted by: kevinthenerd

Originally posted by: AdamK47

Originally posted by: kevinthenerd

Originally posted by: AdamK47
Horsepower sells the car. Torque wins the races.

Wrong.

Horsepower does sell cars. It's marketing 101 for cripes sake!

Torque doesn't win races.

HP=torque*RPM/5252. If torque is 0. HP is 0.
/techinicality FTW!

LOL. You got me, but I hope you didn't lose the point here. To win races you need torque AND rpm.

 

[Summitdrinker]

well back in the 70's top fuel rail cars, were running 426 hemi based motors, nitro and supercharged..........................they never went above 6000 rpm, the tranny??????????? was a 2 speed. at the time they went about 200 to 220 mph at the end of 1/4 mile
it was both HP and torque, but really they were torque motors and the key was a wide high torque band

 

[kevinthenerd]

Originally posted by: Summitdrinker
well back in the 70's top fuel rail cars, were running 426 hemi based motors, nitro and supercharged..........................they never went above 6000 rpm, the tranny??????????? was a 2 speed. at the time they went about 200 to 220 mph at the end of 1/4 mile
it was both HP and torque, but really they were torque motors and the key was a wide high torque band

Did they use torque converters? Modern top fuel cars don't even have gears. They mostly just slip. It's still power that gets you down the track. Have you ever listened carefully to a highly tuned muscle car in a quarter mile? They typically launch at 6000 rpm. You can make power with lots of torque and some rpms or lots of rpms but some torque, but you can't suck at both and still make power. Torque alone will get you nothing. You need torque and revs; in other words, you need power. It wasn't a wide torque band that helped them do so well; it was a wide power band.

 

[Summitdrinker]

ya I think it had a TQ with two speed auto, but I am unsure

well look at the old muscle car debate; B body mopar 426 hemi against the 455 buick GS
who won? it was close. the buick didn't have that much HP, it had more torque at low rpm's compared to the hemi

true were talking about street cars, not race only cars

 

[Gillbot]

Originally posted by: kevinthenerd

Originally posted by: Summitdrinker
well back in the 70's top fuel rail cars, were running 426 hemi based motors, nitro and supercharged..........................they never went above 6000 rpm, the tranny??????????? was a 2 speed. at the time they went about 200 to 220 mph at the end of 1/4 mile
it was both HP and torque, but really they were torque motors and the key was a wide high torque band

Did they use torque converters? Modern top fuel cars don't even have gears. They mostly just slip. It's still power that gets you down the track. Have you ever listened carefully to a highly tuned muscle car in a quarter mile? They typically launch at 6000 rpm. You can make power with lots of torque and some rpms or lots of rpms but some torque, but you can't suck at both and still make power. Torque alone will get you nothing. You need torque and revs; in other words, you need power. It wasn't a wide torque band that helped them do so well; it was a wide power band.

I'll agree to some extent.

Torque gets the car moving, horsepower keeps it moving and accelerating. IE, torque over time or work which = power.

For example, you can launch a "highly tuned muscle car" at 6000 RPM's but without proper GEARING, that power is useless. That would be the equivalent of launching at 6k RPM but with the transmission in overdrive. Torque is multiplied through all the gearing to get everything going, then power "takes over" as the gearing increases.

Yes, this is not the proper description but I think it describes what i am trying to explain.

 

[Summitdrinker]

as you go up the gears, you need more torque

 

[Pacfanweb]

Originally posted by: kevinthenerd

Originally posted by: Summitdrinker
well back in the 70's top fuel rail cars, were running 426 hemi based motors, nitro and supercharged..........................they never went above 6000 rpm, the tranny??????????? was a 2 speed. at the time they went about 200 to 220 mph at the end of 1/4 mile
it was both HP and torque, but really they were torque motors and the key was a wide high torque band

Did they use torque converters? Modern top fuel cars don't even have gears. They mostly just slip. It's still power that gets you down the track. Have you ever listened carefully to a highly tuned muscle car in a quarter mile? They typically launch at 6000 rpm. You can make power with lots of torque and some rpms or lots of rpms but some torque, but you can't suck at both and still make power. Torque alone will get you nothing. You need torque and revs; in other words, you need power. It wasn't a wide torque band that helped them do so well; it was a wide power band.

Modern top fuel cars don't have TRANSMISSIONS. They certainly have rear end gearing. They have a multi-disc clutch pack that gradually locks up on the way down the track. It's basically a single-use CVT, in effect.

Back when the cars had trannys, they still used clutches. The torque converter that can stand up behind a fuel engine doesn't exist yet.

And yes, it was a wide torque band also. Torque and HP aren't mutually exclusive....can't have one without the other. By having a wide power band in a nitromethane fueled engine of 500 cubic inches, you automatically have a wide torque band.

 

[kevinthenerd]

Originally posted by: Pacfanweb

Originally posted by: kevinthenerd

Originally posted by: Summitdrinker
well back in the 70's top fuel rail cars, were running 426 hemi based motors, nitro and supercharged..........................they never went above 6000 rpm, the tranny??????????? was a 2 speed. at the time they went about 200 to 220 mph at the end of 1/4 mile
it was both HP and torque, but really they were torque motors and the key was a wide high torque band

Did they use torque converters? Modern top fuel cars don't even have gears. They mostly just slip. It's still power that gets you down the track. Have you ever listened carefully to a highly tuned muscle car in a quarter mile? They typically launch at 6000 rpm. You can make power with lots of torque and some rpms or lots of rpms but some torque, but you can't suck at both and still make power. Torque alone will get you nothing. You need torque and revs; in other words, you need power. It wasn't a wide torque band that helped them do so well; it was a wide power band.

Modern top fuel cars don't have TRANSMISSIONS. They certainly have rear end gearing. They have a multi-disc clutch pack that gradually locks up on the way down the track. It's basically a single-use CVT, in effect.

Back when the cars had trannys, they still used clutches. The torque converter that can stand up behind a fuel engine doesn't exist yet.

And yes, it was a wide torque band also. Torque and HP aren't mutually exclusive....can't have one without the other. By having a wide power band in a nitromethane fueled engine of 500 cubic inches, you automatically have a wide torque band.

Torque and horsepower aren't completely mutually exclusive, but if you had to choose between racing a high torque, low horsepower engine vs. a high horsepower, low torque engine, you'd be a fool for choosing the high torque engine.

By the way, saying that an engine has "more torque than horsepower" is like saying I'm heavier than I am tall. They're different units, and they mean different things. The only thing you're comparing is the number in front of the unit, and it's only a matter of convenience from our unit system that they're on the same order of magnitude with eachother.

 

[Pacfanweb]

Originally posted by: kevinthenerdTorque and horsepower aren't completely mutually exclusive, but if you had to choose between racing a high torque, low horsepower engine vs. a high horsepower, low torque engine, you'd be a fool for choosing the high torque engine.

Depends on what kind of racing you're doing. A big block engine with 500hp is going to have more torque than a small block with the same 500 HP, and is always going to out-accelerate the small block if everything else is equal. Reason is, I believe, that the higher-torque engine will have a broader powerband.
I think that the theoretical top speed might be the same, but the I'm pretty sure the acceleration won't be.

By the way, saying that an engine has "more torque than horsepower" is like saying I'm heavier than I am tall. They're different units, and they mean different things. The only thing you're comparing is the number in front of the unit, and it's only a matter of convenience from our unit system that they're on the same order of magnitude with eachother.

Most dynos measure torque and use calculations to get the HP from that measurement. I sort of get what you're saying, but I can't agree that they are as different as the example you mentioned.


Here's a great discussion in a physics forum about Torque vs HP...makes my head hurt

 

[Demon-Xanth]

Originally posted by: kevinthenerd
Torque and horsepower aren't completely mutually exclusive, but if you had to choose between racing a high torque, low horsepower engine vs. a high horsepower, low torque engine, you'd be a fool for choosing the high torque engine.

By the way, saying that an engine has "more torque than horsepower" is like saying I'm heavier than I am tall. They're different units, and they mean different things. The only thing you're comparing is the number in front of the unit, and it's only a matter of convenience from our unit system that they're on the same order of magnitude with eachother.

I've driven a 2.5RS (Subaru), Civic, an Integra, and a Prelude. All three had different engines, and respectively were lower revving to high. And frankly, the driving experience was favorably towards the other way. Even though the 2.5RS had 35 less HP than the Prelude, it felt much more usable and less annoying. The Subaru was the ONLY one that I thought actually felt good. The Prelude you had to choose between driving slow or driving fast. If you wanted to speed up, you had to drop two gears, if you wanted to cruise or came up to traffic, you had to either shift or the car would be jumpy and sound like a pissed off hornets nest. It couldn't be somewhere in the middle. Unless it was above 5500RPM, it wasn't fast at all.

That is why I choose the (reletively) low revving engines. They're more comfortable in the place between slow and fast.

And remember, a 2L engine at 8000RPM pumps as much air (ideally) as an 8L engine at 2000RPM. Don't expect the 2L engine to be magically fuel efficient when asked to be held at high RPMs to compensate for a lack of torque.

 

[Summitdrinker]

so if we take a new cummins desiel engine, put it in a small rear drive car that weighs about 3200 pounds, put a 6 speed manual over drive tranny in it and rear end with over drive gear ratio, like 0.7 to 1 ratio, well what will you have??????????????????????????????


















a car that is rather slow from zero to 150 mph, but tops out at like 250 mph, but why can't 500 hp chevy 350 engine get that top speed not matter what the gearing is

 

[91TTZ]

Originally posted by: Demon-Xanth

If someone designed a CVT that could handle high power/torque, have low drivetrain losses, is light, and is reliable, then you could concievaly program a sports car to go to peak power, and stay there until the RPM drops below or goes above the limits of the ratios.

That's why those old fashioned Powerglide transmissions are so popular at drag races. They're simple and sturdy, with only 2 or 3 speeds. They slip the torque converter the whole time and stay at a near-constant RPM. It's not very efficient, but it's better than the alternative when you're using it in a drag race.

 

[91TTZ]

Originally posted by: Summitdrinker
so if we take a new cummins desiel engine, put it in a small rear drive car that weighs about 3200 pounds, put a 6 speed manual over drive tranny in it and rear end with over drive gear ratio, like 0.7 to 1 ratio, well what will you have??????????????????????????????

a car that is rather slow from zero to 150 mph, but tops out at like 250 mph, but why can't 500 hp chevy 350 engine get that top speed not matter what the gearing is

Simple. It won't work that way.

The car with more HP will have a higher theoretical top speed than the diesel engine, assuming you gear them both correctly.

 

[Zenmervolt]

With a fixed number of gear ratios available, you're best off to have a wide, flat torque curve that extends from low to high RPM. Gearing can "manufacture" torque, but eventually you have to shift and the wide powerband allows you to pull through each gear with less reduction in pulling power.

If you have something like a CVT then the transmission can accommodate a much narrower powerband, and having the torque at higher RPM as you've described is definitely beneficial there.

ZV

 

[drpootums]

Originally posted by: kevinthenerd
Otherwise, the driver shouldn't really care about how fast the engine is spinning unless they're looking for a particular sound or something else irrational like that.

Not exactly. Wear on your engine (particularly the piston rings) is close to the square of engine speed. The faster your engine spins on average, the faster your rings (and other engine internals) will wear out, and the faster your engine will require a rebuild. If the driver wants his engine to last at all, he should care about how fast it's spinning. Some engines are designed to rev higher on average than others (4 cylinder engines vs. V8 engines), but in the end, higher revs = increased engine wear.

I know this isn't exactly the point of the thread, but I wanted to comment on that.

 

[Summitdrinker]

ok HP determines top speed not torque

 

[marincounty]

Power=work per unit of time
It's power that matters, unless you are trying to tow something from 0 mph, then you want low rpm torque. Interestingly electric motors have peak torque at 0 rpm, meaning that a hybrid truck or SUV could be an outstanding tow vehicle.
Power matters, that's why Formula 1 engines, limited to 2.4 liter V-8s, rev to 19,000 rpm, and make over 700 hp with minimal torque.

 

[overst33r]

Originally posted by: marincounty
Power=work per unit of time
It's power that matters, unless you are trying to tow something from 0 mph, then you want low rpm torque. Interestingly electric motors have peak torque at 0 rpm, meaning that a hybrid truck or SUV could be an outstanding tow vehicle.
Power matters, that's why Formula 1 engines, limited to 2.4 liter V-8s, rev to 19,000 rpm, and make over 700 hp with minimal torque.

That is because it is the only way to make so much power out of such a small engine.

 

[Demon-Xanth]

Yup, engines are air pumps and the fuel burns with a particular ratio. If you want to make more power, you need to get more air though it. Revving higher, adding displacement, or compressing the air on it's way in, or simply improving the design is how it's done.

 

[Pacfanweb]

Originally posted by: mariok2006

Originally posted by: marincounty
Power=work per unit of time
It's power that matters, unless you are trying to tow something from 0 mph, then you want low rpm torque. Interestingly electric motors have peak torque at 0 rpm, meaning that a hybrid truck or SUV could be an outstanding tow vehicle.
Power matters, that's why Formula 1 engines, limited to 2.4 liter V-8s, rev to 19,000 rpm, and make over 700 hp with minimal torque.

That is because it is the only way to make so much power out of such a small engine.

Exactly. If F1 was allowed to use larger engines, they wouldn't need to spin them as high to get the same HP, and they'd have more torque as a result.

 

[manowar821]

All I know is that Honda still makes the torqueless wonders, and that's hilarious.

 

[overst33r]

Originally posted by: manowar821
All I know is that Honda still makes the torqueless wonders, and that's hilarious.

Why exactly is that funny?

 

[manowar821]

Originally posted by: mariok2006

Originally posted by: manowar821
All I know is that Honda still makes the torqueless wonders, and that's hilarious.

Why exactly is that funny?

Because of the huge ricer crowd who think that civics are the ultimate racing machines. I have nothing against the cars themselves, or people who love them for what they are.

But when people start bragging about their vtech civics, it makes me giggle a little. I guess I'm just jaded because I've experienced the rx-7 in all it's stock glory.

 

[Ktulu]

Originally posted by: manowar821

Originally posted by: mariok2006

Originally posted by: manowar821
All I know is that Honda still makes the torqueless wonders, and that's hilarious.

Why exactly is that funny?

Because of the huge ricer crowd who think that civics are the ultimate racing machines. I have nothing against the cars themselves, or people who love them for what they are.

But when people start bragging about their vtech civics, it makes me giggle a little. I guess I'm just jaded because I've experienced the rx-7 in all it's stock glory.

But it's Vtech Yo...........

 

[91TTZ]

Originally posted by: mariok2006

Originally posted by: marincounty
Power=work per unit of time
It's power that matters, unless you are trying to tow something from 0 mph, then you want low rpm torque. Interestingly electric motors have peak torque at 0 rpm, meaning that a hybrid truck or SUV could be an outstanding tow vehicle.
Power matters, that's why Formula 1 engines, limited to 2.4 liter V-8s, rev to 19,000 rpm, and make over 700 hp with minimal torque.

That is because it is the only way to make so much power out of such a small engine.

It's the only way according to the current rules, but F1 used to allow turbochargers, and the cars produced more power 20 years ago.