Stingy74

Does maybe the NHRA or somebody publish a conversion for 1/8 mile to 1/4 mile with the same conversion for the mph's? I have a rough idea but it seems inaccurate.

Xracer

Try this it might give you what you want.

http://www.prestage.com/carmath/formulas.asp

Lohkay

There is no real way to convert it because it all depends on where your power is... For exemple, torque is the key on the 1/8 but hp is more important on the 1/4. Take a car that has 250hp and 150lbs of torque and another car that has 200hp and 200lbs of torque and the 200hp car will win in the 1/8. Put the same cars on the 1/4 and the 250hp one will win. Those calculators out there will just give you a very rough estimate of what you should get.

63Banshee

Multiplying the 1/8 mile time by 1.5832 will get you very close to the actual ¼ mile time. It has to do with acceleration characteristics more then power range… especially when you consider most guys are well into third gear by the end of the 1/8 mile mark. Any error in this formula will equal the difference in a ¼ mile time during hot and cold days, or dry and humid days.


Example:

I just found one of my time slips from Texas Motorplex…

1/8 … 7.459
MPH … 90.48
1/4 … 11.821
MPH … 11.66

If you use the formula that 1/8 mile time would translate to 11.809 in a ¼. I remember this race. I actually had to lift 100 feet before the trap because I was pushing 6200 rpm. I figured it would have run 11.78 if I stayed in it. So you see, the formula split the difference.


[Modified by 63Banshee, 1:01 PM 12/6/2001]

63Banshee

One more thing... If your car is a dog off the line or spins the tires like a "Banshee" :D then the times won't be nearly as close.