can somebody explain what torque and hp mean in car advertising

[iwantanewcomputer]

torque = F*r
power = w/t = F*d/t = m*a*d/t (non-rotational)

I'd guess that torque should be all i care about.

power just gives the same units as torque divided by time.

 

[Eli]

It appears as if you've answered your own question......

 

[se7en]

torque will take you 0-60 from a stand still

hp will take you from 60ish to 180 =)

bah on numbers.. ..

 

[her209]

Torque is measured at the drive shaft, right?

 

[Demon-Xanth]

HP=(torque*RPM)/5252

I'd rather see torque curve graphs published, but most manufacturers won't do that. Especially when they have spikey curves that only have high end HP. You can get an idea of what it looks like by the spacing of the torque and HP RPM figures. If the peak torque is over 5252RPM, consider the car torqueless.

 

[Demon-Xanth]

Note the difference between these two charts:
Stock 4.7 Dakota, and modified throttlebody:
http://www.fbthrottlebodies.com/images/charts/4_772mm4inchvsstocksmall.gif
(rear wheel HP+torque)

Description is on the picture (Integra):
http://www.hstuners.com/articles/product-reviews/SKUNK2VSTypeR.jpg

 

[CrispyFried]

Torque is what smokes your tires on the holeshot and what pulls you out of that mud hole. Horsepower is what gives you that 130 mph top end.

 

[Jassi]

Carmakes have a saying:

Horsepower sells cars, Torque moves them.

 

[Demon-Xanth]

Although there's a 30HP difference in the base runs, there's a massive 143LBft difference. In the case of the two vehicles, the former pushes a 4000LB vehicle to a mid-high 15 second quarter mile time. The latter pushes a 2600LB vehicle to high 14, low 15 times.

Edit:
...I wonder what it'd take to shave 1400LBs off a Dakota...

 

[DingDingDao]

Numbers are useless without figures. If your car makes 300 lb-ft of torque, but it's at 5500 rpm, it's pointless. As is 400hp if it doesn't kick in until 6000 rpm (read: VTEC).

 

[fbrdphreak]

Originally posted by: Demon-Xanth
Although there's a 30HP difference in the base runs, there's a massive 143LBft difference. In the case of the two vehicles, the former pushes a 4000LB vehicle to a mid-high 15 second quarter mile time. The latter pushes a 2600LB vehicle to high 14, low 15 times.

Edit:
...I wonder what it'd take to shave 1400LBs off a Dakota...

Good example

There's another good saying I like:
"Horsepower lets you hit the wall at 120mph. Torque takes the wall with you."
Or something like that, my memory is fuzzy

 

[mb]

Take the 2003 Toyota 4Runner for example.
Specs are either:
4.7L 235 hp V8 (320 ft/lb @ 3400 RPM)
4.0L 245 hp V6 (283 ft/lb @ 3400 RPM)

We can see that while the V8 has less horsepower, it has more torque.

Take a look at the performance stats now:
0 - 60 Time (seconds) 1/4 Mile Time (seconds) 1/4 Mile Speed (mph) Braking 60 - 0 mph (ft.)
V8 4.7L (235 hp) 7.13 15.61 88.70 125
V6 4.0L (245 hp) 8.28 16.33 86.20 135

The V8 with more torque outperforms the V6 with more HP.

 

[91TTZ]

Originally posted by: iwantanewcomputer
torque = F*r
power = w/t = F*d/t = m*a*d/t (non-rotational)

I'd guess that torque should be all i care about.

power just gives the same units as torque divided by time.

It's actually the other way around.

Horsepower already accounts for torque and adds RPM to the mix (HP= [tq x rpm]/5252) Torque itself doesn't tell you much. You cannot have horsepower without torque, but you can have torque without horsepower. You could have 500 lbs of torque and do absolutely no work. An electric car will have torque even if it's pressed against a wall going nowhere. That motor will be producing a lot of torque, but no HP at all since it's not turning.

Horsepower tells you about the amount of work it does. Torque is only a single element of that and is meaningless by itself. This is theoretically speaking, of course. In reality, on an engine you do want loads of torque.

 

[Promethply]

If you race two identical cars, except one of them have its engine tweaked to produce greater torque, the tweaked car would accelerate quicker.

 

[91TTZ]

Originally posted by: Promethply
If you race two identical cars, except one of them have its engine tweaked to produce greater torque, the tweaked car would accelerate quicker.

Realistically, you are correct. In theory, both should accelerate at the same rate if the HP is equal, but reality never plays out like that.

 

[NiKeFiDO]

Torque is the thing thats lets you accelerate up steep hills while still in 5th gear (aka still able to pick up speed). Its the power per rotation of drive shaft....?...yeah, that came out of my ass....

 

[91TTZ]

Originally posted by: NiKeFiDO
Torque is the thing thats lets you accelerate up steep hills while still in 5th gear (aka still able to pick up speed). Its the power per rotation of drive shaft....?...yeah, that came out of my ass....

lol

It's the other way around though. The "power per rotation" of the crankshaft, to very loosely put it, is the Horsepower.

Torque doesn't take rotation into account. It's horsepower that does.

Horsepower equals (torque x RPM) divided by 5252.

 

[Subbaculcha]

Originally posted by: 91TTZ
Torque doesn't take rotation into account. It's horsepower that does.

Of course it does. Torque by definition is a measurement of ROTATIONAL force.

HP is a measure of work, it doesn't by definition need to be rotational.

 

[Eli]

Originally posted by: Subbaculcha

Originally posted by: 91TTZ
Torque doesn't take rotation into account. It's horsepower that does.

Of course it does. Torque by definition is a measurement of ROTATIONAL force.

HP is a measure of work, it doesn't by definition need to be rotational.

Yep...

Who's got it backwards now? lol

 

[91TTZ]

Originally posted by: Subbaculcha

Of course it does. Torque by definition is a measurement of ROTATIONAL force.

HP is a measure of work, it doesn't by definition need to be rotational.

No, it most definitely does not.

Torque is a unit of force, not work. Work requires movement, and movement denotes work being done. Rotation is movement. If torque took rotation into account, it would be a unit of work, not force.

If you put a wrench on a seized up bolt and tried unsucessfully to turn it, you'd be applying torque to the bolt, but there would not be rotation. Therefore no work is being done. As you can see, torque can exist without rotation.

However, horsepower cannot exist without rotation. That's because it's a unit of work, which is more involved than a unit of force. If you held the shaft of an electric motor so that it could not turn, the motor would still be putting out torque, but there would be 0 horsepower, since it cannot exist without movement. Torque, on the other hand, can.

Now like I originally said- Torque DOES NOT take rotation into account.

 

[91TTZ]

Originally posted by: Eli

Yep...

Who's got it backwards now? lol[/quote]


You don't make yourself look any brighter when you support the guy who is wrong and talk crap about it.

Who's got it backwards now?

It looks like you both do.

I'm on technical car forums all day, and I'm up to a pretty good level of technical discussion on there. Then I come to non-car forums like ATOT, and I see very basic questions being asked. I am shocked that I meet resistance from idiots who want to argue with me about the most basic things. You don't know what you're talking about, I do.

You can either face the facts, or you can make me own you by posting various links that state what I find to be obvious.

Like I said. Torque is a unit of force, and does not take motion into account. Whether any motion comes as a result of the torque is a completely seperate issue that's not a pre-requisite.

 

[StageLeft]

I've noticed that you can more easily predict a vehicle's 0-60 on its HP than its torque. Case in point: Honda S2000 has similar torque to weight ratio is a VW TDI. Think they get 0-60 similarly? Hell no. The S2000 has 240 hp vs 90.

As I mentioned in another thread I can gear it such that I can produce a million foot lbs of torque on my bike. The problem is that that torque will give me incredible force but it can't accelerate quickly at all.

If you can have a car produce 200 torque over a nice long range of RPM and another car that peaks at 250 but then quickly drops to 110, the 200 will do better.

People like to make simplistic statements like torque is good for acceleration and HP good for highend, etc. but it's not that simple.

howstuffworks.com has a nice article on torque and hP.

Of course it does. Torque by definition is a measurement of ROTATIONAL force.

HP is a measure of work, it doesn't by definition need to be rotational.

Yep, but do remember that torque doesn't represent the amount of work that can be done, pursuant to my one million foot lbs of torque on my bicycle.

 

[iwantanewcomputer]

ok so in comparing engine specs one should really ignore hp and look at torque.(and not max torque but the whole torque vs. rpm curve)

 

[91TTZ]

Originally posted by: Skoorb

howstuffworks.com has a nice article on torque and hP.

Of course it does. Torque by definition is a measurement of ROTATIONAL force.

HP is a measure of work, it doesn't by definition need to be rotational.

Yep, but do remember that torque doesn't represent the amount of work that can be done, pursuant to my one million foot lbs of torque on my bicycle.

These young fools who argue with me don't seem to comprehend the issue. They don't understand that torque is a unit of force and NOT a unit of work or power. Torque does not measure movement, it does not take movement into account. If they want movement to be part of the unit, they're looking at work, not torque. And if they want a time factor in there, they're looking at a unit of power, such as Horsepower.

 

[StageLeft]

Originally posted by: iwantanewcomputer
ok so in comparing engine specs one should really ignore hp and look at torque.(and not max torque but the whole torque vs. rpm curve)

Read the thread again.

EDIT: If you can pick only one to go but I'd always go by HP