"I wish people would just quit talking about torque entirely. It is irrelevant."

Tim,
This is not true at all. Adding more torque across the rpm range will win a drag race everytime over more hp across the rpm range. Torque is what you want to look at for drag racing and hp should be second.

Now if you were talking about road racing where the rpms can stay higher, then hp is king.

 

you guys are saying _almost_ the same thing... just using different words.

racetested... I'm sure you realize that "more HP across the rev range" will also mean you're making more TQ across the rev range. You can't make HP without TQ as a function of rpm, and you if are making TQ, then you're making HP.

What is important is the HP produced over the rev-range in which you're racing in. If you've got a 3000rpm stall, that flashes to 3500 on launch on slicks, then all you care about is 3500-redline. Then on the upshift, how much does the rpm drop? Maybe to 4000-4300 or so. At this point, how much TQ (or HP) you make below this rpm is completely irrelevent. All you care about is HP produced.

If TQ wins races, then we'd all be throwing in 1500ft/lb turbo-diesels in our Lightnings. But it doesn't work that way b/c by 3000rpm, the thing is dead in the water. Average HP (which is certainly a function of TQ. No one said it wasn't) over the "racing rev-range" is what wins the race. Oh...and of course the ability to put this power to the ground.

Like Blown347 said... losing a bit of low-end TQ/HP is not a big deal when you're already fighting traction issues.

 

Torque and HP and tied to each other. When you have more torque, you will have more HP. If you add HP and are properly geared to keep your engine in its proper RPM range, then you will go faster. If torque was the only factor, then why do people modify engines (which almost always shows a torque loss at low RPM) and these mods which increase HP also make the vehicle accelerate faster? Beacse you can't have HP and no torque.

 

In my defense I said over the rpm range and not in general. You can create more torque by running a richer set-up and run more hp with a leaner set-up. YES hp and torque have a relationship, but you can tweak one to be more or less then the other and not be parallel across the rpm range.

 

So, you agree that having more HP across the RPM range is the more important consideration, and torque would just follow albeit the peak TQ number may have been moved up in RPM?

 

Depends on what type of racing you are doing.

More torque across the rpm range with a rich mixture will make you accelerate better for drag racing. More hp across the the rpm range will make you have higher terminal speeds but slower et's.

Again Et's and power have a relationship but tweaking a little bit can make one better then the other. Do you want a lower E.T or a few miles faster terminal speed?

 

Here's the formula: Horsepower equals torque times rpm divided by 5252. Or in equation form:

Horsepower = Torque X RPM/5252.

You can gain horsepower and loose torque and you can loose horsepower and gain torque. It is all a function of the point where they occur.

If we have an engine that makes 400 lb/ft at 2000 rpm, the math is as follows: 400 x 2000 / 5252 = 152 horsepower.

But if we move the torque peak up to 4000 rpm, things get different: 400 x 4000 / 5252 = 304 horsepower.

So we have the same torque, 400 lb/ft, making entirely different horsepower depending on the engine speed at which the engine is rotating. Why? Torque is a measure of work and horsepower is a measure of how fast it gets done. Lifting an object (like an engine) takes a given amount of work. If you do it with a chain hoist and it takes 30 seconds or a forklift and it takes 5 seconds, the work done is the same. The difference is in the time taken.

 

 

I just got my truck up and running a couple days ago with a ported blower.

It reminds me exactly of doing a very mild port job on a two stroke motor (banshee) I seem to have lost a little bottom end, but mid range hits harder...... and obviously more power up top.

Is it a good mod for the average Lightning owner ?

Unless I was drag racing every weekend at the track, I am not sure I would do it again.

 

Kerno,
Thanks for offering the formulas and explanation as I didn't feel like digging for them.

Point is things are not that black and white. That's why I kept saying depends on what type of racing you want to do or design a motor for. You can manipulate factors but which wat depends on the application on hand. There is no set linear movement between hp and torque as a few have mentioned.

Patrick,
Good comparison also.

 

Whoever says torque is irrelevant, go test drive a Honda S-2000. Lots of HP but from a stop light it's dead.

TB

 

Was curious what upper and lower pully combinations people are running with the ported blowers..Anyone running an 8lb lower with a 2.8 upper??

 

Trackbeast,
I was going to say the same thing about my girlfriends Honda Civic as an example. I had to drive it the other day to do some maintenance on it and I can't pull out into heavy traffic as it doesn't take off like my truck can. I was getting a bit irritated and missing my truck to say the least.