$ Building a Slant 6 for performance
I thought his point was pretty self explanatory.
I didn't. It's a not-so-simple situation, regarding torque and horsepower.
For the purposes of our discussions (automobile engines,) horsepower is a number that is arrived at, mathemetically, with torque being one of the factors and rpm the other.
Like the song says, you can't have one without the other...
Torque is twisting force. Horsepower numbers are arrived at by crunching the numbers related to the RATE (RPM) of the torque being produced.
How this plays out is this:
Let's say you have 500 foot pounds of torque at 6,000 rpm. If you reduce the amount of rpm to 3,000, while maintaing the same amount of torque, your horsepower will be cut in half. The same thing is true if you maintain 6,000 rpm and reduce the available torque to 250 foot pounds; your horsepower will be cut in half.
One horsepower is the ability to raise 42,000 pounds one foot, vertically, in one minute. Or, 21,000 pounds, the same distance vertically, in 30 seconds... and on and on.
TIME figures into the horsepower equation as
rate of work done.
Torque has no such parameters; twisting force is twisting force. Period!
To show an example of how this works, let's say we have two Dusters that weigh 3,000 pounds each.
One has a 440.
The other has a 340.
The 440 is a mild build with a short-duration cam, 9:1 compression and a 600cfm 4bbl Holley on a 180-degree manifold.
It makes 400 horsepower at 5,000 rpm, horsepower and 500 foot pounds of torque.
The 340 is a more aggressive build, with a fairly long-duration cam, 11:1 pistons and an 750 Holley on a single-plane manifold.
It also makes 400 horsepower, but only 360 foot pounds of torque.
Put them both in the Dusters with optimum gearing and tires and they'll run the same e.t.
They each have 400 horsepower available to move the weight through the quarter-mile. Same weight, same horsepower = same e.t.
BUT, they have wildly varying amounts of torque. Five hundred foot pounds vs. 360.
Doesn't matter; the amount of HORSEPOWER available to move the same amount of weight in the same amount of time, is the same... so, the results will be the same IF they both have setups that take full advantage of their different "personalities."
Lots of gear (5.86:1 and a high rpm stall torque converter for the 340) and not-so-stiff gearing (4.10:1?) for the 440, with a MUCH tighter converter.
So, what wins races?
Horsepower. Same horsepower here = a dead heat.
Lots of torque at high rpm = lots of horsepower.
Lots of horsepower = low e.t.'s.
I'm a mathematical dunce, but even ~I~ can understand that.
A fact that I find interesting, but one that has to do with the way horsepower is determined is, the horsepower and torque numbers will ALWAYS be the same at 5,250 rpm. Always.
Go figure...
