i found this little program that is supposed to calculate HP from your vehicle weight and 1/4 mile times. Dunno how accurate it is but have fun!
http://www.4lo.com/calc/dynocalc.htm

 

Its close

 

wow

 

I wrote a windows version a long time ago:

Window HP Calculator w/ 0-60mph times - Windows version of the horsepower calculator. It will show the minimum, average, and maximum horsepower given the total weight of the vehicle, et, and trapspeed. You can also calculate your 0-60 mph times using the 1/8th mile values

I also wrote a cellphone version so you can use it when at the drag strip:

Horsepower Calculator - Mobile Edition - Java version for use on your cellphone. It will show the minimum, average, and maximum horsepower given the total weight of the vehicle, et, and trapspeed. Here is a direct URL you can download directly from your cellphone: (http://tagtag.com/jestr)

I wrote this for sprocket changing in motorcycles, but the same rules apply for cars:

Topspeed Calculator - Calculate the top speed for each gear given the gear ratios.

 

wow jestr, didn't know you were so good at programming.

could you show how to work it out by hand given the variables. that would be awesome

 

This is on of the best multi-calculators that I've found. Turbo Fast- Turbo calculator 2.3. http://www.turbofast.com.au/freesoftware.html

 

I believe Jestr has a software engineering background. Helps abit i guess.

 

I totally forgot about this, that thing is pretty damn close