Smarter people
than me have calculated that your 1/4 mile elapsed time should be
proportional to total weight over horsepower raised to the power of
1/3. Really what's important is some type of average horsepower at the
engine speeds that you use during a pass except that the start of the
pass is more important than the end. Other factors like traction and
wind resistance have a small impact (at least on my car) and can be
accounted for with what I call a fudge factor. The following formula
seems to work well for my car.
E.T. = 6.1
* ((weight/hp) ** 1/3 )
In this case,
weight is total vehicle weight in lbs including the driver. Horsepower
is peak flywheel horsepower and 6.1 is the fudge factor to account for
traction, air resistance and the fact that the "average" rear wheel
horsepower is less than the peak flywheel horsepower.
The following
calculator is fun to play with for a while. You can see that if
you put in 4200 lbs and 370 hp you get about 13.7 seconds which is
about right for the stock car.
In racing trim, I think that my
total
weight is about 4100 lbs because I remove the spare tire and a few
other things. This seems to indicate that my peak flywheel
horsepower in ideal conditions must be nearly 485 hp. In reality I
think that it's probably nearer 450 hp and the rest of the improvement
is due to the torque converter and lower differential ratio.
How much more
power would I need to get a sub 12 second E.T. ?
If I ripped out all the seats and interior trim and all that
unnecessary equipment. How much faster would I go ?