Why does the amount of HP seem to go up exponentially for each second of time you drop. Like in reacent post, it was stated that you need something 1500 hp to push mustang to 7.5 seconds. Yet, you need about 530 to each 11/10s and only about 200 to do 15's(stock). See 300 hp drops you about 5 seconds, yet another 300 doesn't drop you from 11's to 6's. What gives? Thanks~ Arnold

 

Couple of things.

The drag coefficient (Cd) for a car increase as the square of the air speed (vehicle speed).

p - air density
A - frontal area
V - velocity (of air)

Cd = 1/2 * p * A * V ^ 2 (something like that).

You go twice as fast, you'll have 4 times the drag on you.


Also another (simply stated) is how distance is related to acceleration. This example is for constant acceleration.

d - distance
a - acceleration
t - time

d = 1/2 * a * t ^ 2

t ^ 2 = 2 * d / a

or

t = (2 * d / a) ^ 0.5

So, if we want to cut our time in half, we have to accelerate 4 times greater over the same distance.

And

F - Force
m - vehicle

F = m * a

So if we want to accelerate 4 times faster, we need to apply a force 4 times greater. Torque directly relates to force, so torque needs to go up 4 times also.

Horsepower = Torque * RPMs / 5252

If torque is increased 4 times, power also increase 4 times.

These are simple equations that explain the jist of it. You can see why you must get so non-linear when going fast.

[This message has been edited by a73camaro (edited May 01, 2001).]

 

Whoa!!! That was DEEP!

 

Thanks so much for the answer, you explained it very well. ~Arnold