ldollar

Hey all,
At the risk of being publicly flogged to death for posing the stupidest questions on the entire worldwide web....

I am trying to gain a better understanding of what exactly TORQUE is and how it translates to real world applications (i.e. driving). I am trying to understand how exactly torque and horsepower relate to or affect each other.
Is there a simple way to explain the difference between horsepower and torque?
For example, in the following chart...
At 3750rpm, my hp is at 245 and my trq is 340.
At 4800rpm, my hp is at 328 and my trq is 358.
How does the torque affect my ability to access the horsepower? Or is it vice versa? Am I making any sense? Thanks guys, and please... Dont tear me a new one!

remicks

Torque as I understand it is the stump pulling power of your car. Basically its the factor that matters to get you off the line in a timely manner. Horsepower is what keeps you going fast after your intial push of the torque, also it factors into your top speed with a combo of your gearing.

Unless you are racing more than stop light to stop light I believe that torque is the more important stat.

67mustang302

They're not seperate entities. Horsepower is a measurement of work over time, torque is a measurement of force. Amazingly you asked a question that rareley gets asked, but doesn't get asked nearly often enough. Horsepower and torque are related via engine speed.

http://www.epi-eng.com/ET-PwrTrq.htm

ldollar

This is fascinating stuff.
I was just browing through that link you provided, 67mustang302 and it was a lot of good information. A little more than I am going to be able to digest at this hour of the night but just looking at the basics in the first 1/2 of the article helps.
Hmmmm. I better sleep on this one.
Cheers all, and thanks again for all your help here.

Starfury

All you need to remember is that HP = Torque x RPM รท 5252. HP is an imaginary numbercalculated from torque.

The saying goes: horsepower sells cars, torque wins races.

ldollar

Thanks, Tad. That keeps it real simple. So what do you think of my torque numbers from the dyno? Decent?

67mustang302

The last part of the article in that link I posted, the guy actually does a break down of where the 5252 comes from in the equation, which I thought was pretty neat

mySAVIOReigns

Are you an ME? I've only met a handful of people who knew that, and they were all MEs, like myself.

THUMPIN455

To break it down to simple laymans terms, Torque is a measurement of the twisting force of the engine. Just like they said above, HP is a mathmatical equation of torque over time. They should always be the same at 5250 rpm because that is the divisor. If you make your torque above 5250 rpm you will have more HP.

An extreme example is a diesel vs a 289. Lets say they are both 400hp engines, but the 289 can rev to 8000rpm and the diesel to 3000 rpm. Lets say that is the HP peak for both engines.
The 289 only has to make 265fltlbs of torque to make 400hp @8000 rpm.
The diesel has to make 700ftlbs to make 400hp @ 3000 rpm.

Still they make 400hp, but the 289 wont pull what the diesel will, it wont move a vehicle as easily unless you can get the RPM up to 8000rpm. To move the torque curve that far up you will sacrifice bottom end power, and an engine built that way would be a dog to drive around.

The import kids who brag about 200 or 300 hp from a tiny engine are being fooled by math into thinking they have something awesome. They make all the power over 5000 rpm, very little torque under 5000 rpm. So they need to wind it till the rod bolts stretch to get the power out of it, when they do get the power, it isnt as much as a 289 that makes 300hp @ 5000 rpm. That is why they get beat. Of course when you line up with a car that has over 600hp and 600ftlbs around 6000 rpm, they dont have much chance anyway.. Not many have that much power, its fun but you gotta respect it..

If I ever get that car legal/drivable again come on up and you can go for a ride, it never makes lower than 500ftlbs from 2000rpm to 6500rpm, its also a 467ci Pontiac.. big 4.25" stroke makes big torque..

Starfury

Lol, no, but I was an engineer at one point. Honestly, I didn't remember the actual number, had to look that up. But the concept isn't that complex once you understand the relationship between force and power. Basic physics