Originally Posted by wingracer

It's pretty simple really, the more air that is drawn through a carb, the more fuel will be drawn into it as well. Sounds ideal at first right? Well, the problem is that most car motors operate over a very wide range of conditions. So, carbs have evolved all kinds of complicated ways to meter that fuel over all those different conditions. Once things like O2 sensors and computers came along, it was far easier and more efficient to just do it electronically with injectors.

Fortunately, our RC motors don't need a lot of the complications that the real things do. We just want them to make power at wide open throttle and to hold an idle for more than a few seconds. Everything in between is sort of negotiable.

On a real car, if you drop a supercharger on it, you will need more fuel. You do this by putting bigger jets in it. Our carbs use an adjustable needle valve instead of jets. To get more fuel you just turn the needle out. However, if the demand for fuel gets greater than the size of the hole in the needle valve can handle, it will lean out. Just like a fuel injected car with so much boost that the stock injectors can't keep up any more. So you put more injectors on it, or get bigger injectors, or a needle valve with a bigger hole.