Apologies if this is repeated.

"You DRIVE torque, You SPEED horsepower".....can't be more simple.

Unkahal

 

For all practical purposes, the difference between horsepower and torque is gearing.

What I mean is this. On the one hand, you have the L98. It makes about 340 ft/lbs at 3200 rpm with a 4800 rpm redline.
Now take an imaginary F1 engine that makes the exact same torque but from 3200 all the way out to 15,000 rpm.

Put them in otherwise identical C4's and line them up at the drag strip.

When they launch, they're neck and neck. But as soon as the L98 car shifts to second, the F1 car starts pulling away. 340 ft/lbs at 15,000 rpm works out to over 900 hp, btw.

 

One mechanical horsepower lifts 550 pounds (250 kg) by 1 foot in 1 second.





The constant 5252 is the rounded value of (33,000 ft⋅lbf/min)/(2π rad/rev)

 

Oh resdoggie, since you put it that way it clears it right up...(sarcasm). I think my head just exploded!!! Actually, very nicely done.

 

HP is the rate of TQ the same way as speed is the rate of distance e.g, distance is 50 miles but to travel 50 miles in one hour is 50 miles/hr, i.e. the rate of distance. Also, acceleration is the rate of speed i.e. 32 ft/second/second or 32ft per second squared.

 

Every engine makes torque and horsepower. Its design can favor one or the other depending on its intended use. For example, imagine two engines with the same displacement, one with a long stroke and short bore and the other with a short stroke and a large bore. The long stroke engine makes a lot of torque at low rpm due to it's high relative compression, high charge velocity, relatively small valves (think Harley). The short stroke engine makes little power with each stroke, but its large bore allows room for large valves, and can tolerate high rpm due to its low piston speed and short stroke and that's where it makes it power, torque, not so much.

Why is this important, why do we care? Because you can build an engine depending on it's intended use. Back when the the Boss 302's were duking it out with the 302 Z/28's, Chevy needed a high revver and stay within a displacement class, so they destroked the 327 to maximize the bore and have a short stroke favoring horspower over torque. For a daily dependable- slug-it-out-for-the-masses small block usually hooked up to a powerglide Chevy gave you a 307, longer stroke, shorter bore, favoring torque over horsepower. Obviously cams, head porting, carburation, gearing, etc, all play a part as well, but generally speaking high revvers maximize horsepower over torque and stump pullers maximize torque and don't need a lot of rpm. (we're talking naturally aspirated engines here)

 

A Harley has HP,,, a 2 stroke Kawasaki has torque. Both can have 100 hp.

 

The math has been well covered above. It's Torque x RPM x (a constant) = HP

In the automotive application, it might be better described as "where in the RPM range do you want YOUR torque to be?"

You must have a preference! You can not have it all. You must choose where in the RPM range you want the torque to peak. If you want to have a low RPM torque peak, you will make less HP. If you want to make more HP....you need to move the torque peak to a higher RPM point. Remember, ....big HP comes from what ever your torque is... MULTIPLIED BY THE RPM!

You give up lower RPM torque and increase HP by moving the torque peak higher up in the RPM scale.

 

Actually you can have it all. With supercharging, turbocharging, variable valve timing and lift, there are engines out there that can do it all, albiet at the cost of complexity.

 

You can have it all with electric motors too....... run away........run away.............sorry, don't want to start anything........just trying to be funny......

 

I look at it like this
Torque gets you to work everyday.
HP takes all your cash you make at work and leads to divorce in the endless, mindless quest for more.
Both end up breaking the parts in your vette and you dump more into them.

 

All but quick recharge time.

Troof!

 

Tesla Torque / HP curve at different states of charge, just for fun.;-)
Model 3 Performance on a hub dyno showed 750 ft lbs @ 5,500 rpm.
S P100D in Ludacris mode put down 920 ft lbs on a chassis dyno @4,700rpm on it's 3rd pass and was spinning some...

How much torque do you want and where do you want it?

Adam

 

This gentleman's Vette had no torque
So everyone called him a dork
So with a 502 crate
He t-boned a gate
Now he can't eat with a fork