torque and horsepower

[Torched10]

Ive always wondered about the relationship between hp and torque---hers an interesting article http://vettenet.org/torquehp.html

[2010KonaBlueGT]

Ive always wondered about the relationship between hp and torque---hers an interesting article http://vettenet.org/torquehp.html

 

 

Simply defined, Torque is "twisting force". As in, torque wrench....you are measuring the amount of twisting force applied to a fastener.

 

With a engine, you are measuring the amount of TWISTING FORCE the engine is able to produce.

 

Horsepower is simply a *calculation*(a product) of Torque times RPM over 5252...or "power" (as opposed to a measurable "force").

 

 

Phill

[Torched10]

Simply defined, Torque is "twisting force". As in, torque wrench....you are measuring the amount of twisting force applied to a fastener.

 

With a engine, you are measuring the amount of TWISTING FORCE the engine is able to produce.

 

Horsepower is simply a *calculation*(a product) of Torque times RPM over 5252...or "power" (as opposed to a measurable "force").

 

 

Phill

 

thanks Phil--i always wondered which was the dependent variable here,hp or Torque--i alson wondered if cars with the same hp could have different torque at the same rpm, whoch now i know cant happen--although if one engine has its max torque at a lower rpm, it would have less hp even though the torque is the same,right

[2010KonaBlueGT]

thanks Phil--i always wondered which was the dependent variable here,hp or Torque--i alson wondered if cars with the same hp could have different torque at the same rpm, whoch now i know cant happen--although if one engine has its max torque at a lower rpm, it would have less hp even though the torque is the same,right

 

 

The equation to calculate HP is Tq * RPM / 5252.

 

There for (therefor?), 5252 is the *constant* in the equation.

 

Torque and Horsepower will ALWAYS cross (i.e. be the same) at 5252 RPM.

 

The variable is RPM as it is a measuement of speed (revolutions) vs. time (PER MINUTE). Or I should say, "speed AND time"?

 

I'm not a mathaholic so I probably didn't explain it well enough but you should be able to get the gist of the issue with my poor explaination.

 

And here's something interesting (to me) that most people don't know. When you hear people talk about the "power band", that is the area between peak TORQUE and peak HORSEPOWER on a dyno graph. A wide powerband is more desirealbe than a narrow power band on the street whereas a narrow power band may be more desireable on the strip.

 

So if you have a peak torque early in the RPM range with a peak HP late in the RPM range (which will always be the case) you have a much wider "power band". A peak Tq. later makes for a narrow power band.

 

And here's how I translate a dyno sheet: Your torque curve is simply a indication of cylinder fill. If you have a nice flat torque curve, you have a higher percentage of cylinder fill all the way across your RPM range. A torque curve that falls off early is a indication of cylinder fill falling off which is generally due to port flow (supersonic air flow = turbulance = poor flow) or Supercharger efficeincy falling off (belt slippage, heat generated from overspin, cavitation, etc. etc. etc.).

 

So next time you look at your dyno graph, you can see by the torque curve where your cylinder fill (which HP is completely dependant on) is falling off and you can generally figure out why that is. In the case of a forced induction system, it's generally going to be Supercharger efficiency. In a NA system, port flow or cam overlap/timing.

 

People tend to "overthink" a dyno graph but if you just look at it in SIMPLE terms (as I show) it's VERY easy to use a dyno graph as a tuning tool.

 

 

Just thowing some food for thought out there,

Phill

[Blown Away]

Phil, thanks for the info and explanation!!

 

Dan