Originally Posted by
senor honda
A general rule is that a bigger opening gives more flow and will be good for high speed/top end. A smaller opening will create more vacuum and give better acceleration. That's why a full bore race car that runs at Daytona gets beat on an autocross course....and a few other reasons....-Bob
your results may vary...
Yes ,drag engines are designed around power in the upper rpm range and autocross need a balance of mid and high rpm. Yet they can both use the same size T/B.I guess what we need to determine is what is considered big. I personally fell 68-70mm is big. 72 & up is huge for most hondas. I dont think you would see or fell any difference from a 68mm to 70mm t/b if switched.