HP, TQ, RPMs

[Belatti]

Not having to whatch your revs all the time, freeing your right arm to entertain your mistress while driving perhaps?

Well, I like when she grabs the stick to change gears...

[xpensive]

FYI, I drive a 4.6 V8 automatic...

[riff_raff]

In an engine which is better also knowing you can change gear ratios to rev to redline?

Shrek,

Here's your simple answer:

Torque is defined as the ability of an engine to do work.

Horsepower is defined as how fast that same engine gets the work done.

For a racing engine with a transmission, horsepower is most important.

Regards,
Terry

[alelanza]

Way I see it, HP accelerates the car, and torque breaks stuff within the car , which i guess someone else already pointed out. That being said, since most of the times you only get peak values, it's important to know how to read max torque/max hp and the revs at which they occur. Along with gearing, that explains how a 140hp/140tq car can beat a 160hp/110tq car off the line. But again that's just because you are only looking at peak values, instead of looking at the area under the power curve along with respective gearing for the intended use.

I think i once read Mr Enzo saying something along the lines of:

"Horse power sells cars, torque wins races"

Didn't he also think front engined cars were superior as that's how horse carriages worked (in his view)?
I think it also took some convincing to get him to accept disc brakes were better than drum brakes for most applications. Or to acknowledge car development was more than just engine development and that aerodynamics did matter...

[xpensive]

A 720 Hp F1 engine at 18k Rpm have 280 Nm of torque, most BMW street cars have more than that.

[Scotracer]

A 720 Hp F1 engine at 18k Rpm have 280 Nm of torque, most BMW street cars have more than that.

Most BMWs have bigger engines

But if you compare torque about the rear wheels then get back to me

[xpensive]

Head on the nail Scot, head on the nail =D> ...or how about propulsion-force just to make things totally comparable?

[Scotracer]

Head on the nail Scot, head on the nail =D> ...or how about propulsion-force just to make things totally comparable?

In effect the same thing as torque about the rear-wheel if you take into consideration the rear wheel radius.

[xpensive]

Not really, when power is propulsion-force times vehicle-speed, the same power at the same speed will give different wheel-torques with different wheel-radiuses.

[Scotracer]

Maybe I'm just tired but it appears we're getting two different analysis methods confused...

well, it's certainly confusing me

[Flummo]

But if you compare torque about the rear wheels then get back to me

Compare torque at the rear wheels all you like, the more power you have at that particular engine rpm and wheel speed, the higher torque you will have at the wheels.

[Scotracer]

But if you compare torque about the rear wheels then get back to me

Compare torque at the rear wheels all you like, the more power you have at that particular engine rpm and wheel speed, the higher torque you will have at the wheels.

Thank you, Captain Obvious. Now back to your ship

[xpensive]

Maybe I'm just tired but it appears we're getting two different analysis methods confused...

well, it's certainly confusing me

Sorry for coming across as arrogant Scot, but see it another way;
Two identical cars, travelling at the same speed, applying the same amount of Power, while one of the cars has wheel-radius of 0.6 m, the other's got big 0.8 mothers.

With the same Vehicle-speed and Power applied, and when power is Torque times Rpm, two different Wheel-radiuses must give different Wheel-rpm and as a consequence different Wheel-torque, no?

[flynfrog]

one is trading rpm for torque they are both applying the same power. Thus getting the same amount of work done. assuming the engines to be linear and assuming the wheels to be mass-less

[xpensive]

Correct flyn, but I didn't say the two cars were accellerating, why we can forget wheel-mass and engine-characteristics.