HP Calculations and other formulas - The Unofficial BMW M5 Messageboard (m5board.com)

Bart Carter · 3rd November 2001, 20:28

Because of the recent discussions on the E39 Forum, I have posted a thread on "HP Calculations and other formulas" in the Tips and Tricks forum.

This is a fun calculation. The HP is very accurate. The ET is so traction dependent that it only approximates what can be expected. When you can't get traction at higher HP levels it is practically useless.

IvanDias · 3rd November 2001, 21:19

Thanks,

What a good post.

I`m going to have fun putting all those ricer cars figures thru the mill.

One thing though,

Quote - "A simular formula for the ET in a quarter mile can be also calculated, but THIS FORMULA ASSUMES MAXIMUM TRACTION AND GEARING. "

I take it that this means that the driver gets a perfect launch, but also that the gearing and diff ratios are geared for maximum acceleration, to top out at the terminal speed of the qtr mile.

So in other words, the car is designed for the dragstrip.

Ivan.

Bart Carter · 4th November 2001, 00:24

IvanDias, yes you assume right.

But even more is actual tire traction. When you get to big HP, tires become a limiting factor. If you have a stock Civic, you really don't loose much on traction and your gears will keep you pretty much in the correct RPM range.

If you have an M5, and lets just add a Nowack conversion, hehe, traction is going to be very difficult and ET will suffer. But -- you're MPH will be consistant.

And you're also right about "catching" people and even manufacturers about HP claims. Most manufacturers are pretty accurate, but some downright lie.