Can anyone give me an explanation of which does what for you and how they are related? Do you want to increase torque or horsepower for performance gains? It seems like you always here about HP first and then sometimes torque enters the conversation. Which is really more important and why?

 

Torque gets the party started( Like a shot) and the Horse Power keeps it going(Like a keg) :cheers:

 

The absolute BEST description of what both are and what they get you can be found here: http://www.vettenet.org/torquehp.html

 

Really, Torque is all that matters. Horsepower is a calculated value based off Torque at a certain RPM. The formula is HP=TQ*RPM/5252. That is why all dyno graphs sho the HP and TQ curves crossing at 5252. More torque is always better as long as it doesnt die off early, and the more TQ you have the more HP you have, especially in higher RPMs.

 

Have read that many time. It is a very good explaination.

 

Actual the are are related to each other I think the Formula for Torque = H.P./5250

That's why if you look a a HP vs FT lb they always cross at 5250

Torque is what gets the car moving Power at the low R's


H.P. get you that top speed


Think of this : motorcycles (Rice Rockets inline 4's)are fast they may very little torque but are stupid fast If you ever ridden one you've notice that there is no power down low it's all when you get going higher RPM's)

Now a Mac truck has a lot of torque it can pull tons of weight but we can agree that they aren't to fast.

The key is to have a good balance You neet the torque to get a goo launch (60' time) and you need the HP to run hard down the end of the track.


Having to much torque and not enough HP cause your car to fall on it's face having alot of HP and no torques takes to long to get going.

Hope that didn't confuse you to much

 

Thanks for that link. It's exactly what I was looking for. :cheers:

 

That link is excellent. Main point is both are important, but depending on how they are arrived at, either can be better. Take this as an example...

Assuming both cars weight the same, which is faster? Neither HP nor TQ is king...you have to see the curves.

 

Don't keep us in suspense Warlock! Which one is faster? :D

 

Tq is where its at baby!

 

Torque alone means nothing to performance. Rosie O'Donnel sitting on a sesaw may have 1000 ft lbs of torque!

It's only a long, flat horsepower curve that matters.

 

Some food for thought; Torque is probably more important for a heavy street car going from stop light to stop light. HP is a function of torque x RPM's and when we drive down the street we aren't normally going over 100 MPH. The most important aspect of all this is dependant on the type of driving you are planning on doing and the transmission and rear gear ratio's. You probably wnat to maximize the torque band between 2,500 - 5,500 RPM's, where the RPM band will lie between shifts. One of the best ways to maximize the 2,500-5,500 Torque/HP band is to change rear gear ratio's. :D

 

When running 1/4 miles it's torque that gets good E.T.'s but it takes horsepower to have a high MPH. :crazy:

Makes sense to me. :yesnod:

 

Torque is the engines ability to do work. Power is the rate at which the work can be done. Power is a derivative of torque. If I have a certain amount of torque at a certain engine speed then I can calculate power. They are both important. If I have alot of power, but it all comes at high engine speed, then I better have alot of gears if I want to go fast. Otherwise, I'll have alot of power as I get to redline, will have to shift, and will drop down to an engine speed range where I have little torque - it will take a long time to accelerate back to where the engine makes alot of power. Given two engines that have the same power, the one that has a fatter torque curve (i.e. one that has more torque at a lower engine speed) will be faster. How fast (acceleration wise) I can go will be related to the area under the speed torque curve.

 

I think you got that backwords, not the Rosie O'Donnel, the other part.
H.P. IS calculated off of torque, thus if your torque falls on it's face, HP will go with it. That's why these ricers can make good PEAK HP numbers but still get killed off the line. They might not make much torque, but since HP is calculated off of torque & RPM, the HP numbers can be high. A car that makes 300 pounds of torque at 3000 rpms, has X amount of HP. Now if the same car could turn 300 pounds of torque at 9000 rpms, HP would be much higher.

So what you want is your TORQUE curve to be flat, and that will make the HP build in a straight line. A "flat" HP curve would mean that your torque fell off the face of the planet. Look at my dyno graph for example, if my HP curve was flat, my torque curve would have to fall as the RPM's get higher, you don't want that.

This isn't my latest dyno graph, but it's the best representation because HP and torque are plotted on the same scale.



What is important aside from peak numbers is the "area under the curve" This area works as your "total torque" and "total hp" the larger these numbers are the faster your car will be all around. A flat HP curve would be bad because it would mean a declining torque curve, when torque equals 0, HP equals 0 again as well, so you don't want that at all.

That's why these high reving imports are so slow off the line, they might put up some healthy HP numbers in the very high RPM's, but the rest of their revs are useless. Personally I'll take my 6300 rpm's that every inch of is useful and I can't hardly be in the wrong gear over one of thse 9000 rpm motors in which only the top 1500 does me any good.

 

A very smart man in the peformance game once said, "You sell horsepower and drive torque".

 

You hear about HP numbers the most because that's what sells.