i'm building a locost trike using a motorcycle engine and i'm wondering if i will need to add a turbo to get decent performance. i know the performance numbers for the bike and i know the approxamet weight of the final car, dose anyone have a way to calculate the final performance.

There's a DOS application called "cartest" which you can add all your available information to to get approximate figures - google for it cheers
Bob

Cartest is a good program but if you want to get a quick estimate of the performance I'd say top speed will be about the same, maybe a bit lower due to increased aero drag, and for an idea of 0-60 take the 0-60 of the bike, divide by the weight of the bike and multiply by the estimated weight of the trike.

Pete