Single 48mm Throttle Body VS Dual 44mm Carbs

Hey everyone! The question has been asked so many times. What is better a single throttle body or dual ITBs? So here is some data for you guys. As you can see, the single gives a big boost in low-end HP and TQ,. Unfortunately, the logs for the single were not recorded under 2500rpm. But if you check out the green trace, that is 25% more HP and TQ at 2500. I averaged out the numbers from 2500 to 3500 and that is 7% better. Over that, the single falls short by 3% to the dual ITBs, then it catches right back up at the top. It must be the harmonics in the runner length giving it a boost at the end.

So, if you are building a daily, spend a lot of time in traffic, and aren't on the throttle constantly, the single will do the job extremely well. No linkage, no syncing, no worries. Heavy bus? This will get you off the line better.

If you like to rev your engine out at each shift, love the ITB growl (who doesn't), or like to hit the track from time to time and don't mind a little extra maintenance you will probably be better off duals.

Engine 2180cc - FK7 - Panchito Heads - 9:1 Comp

Here are the engines side by side -