I'm just curious how you can basically bolt on a supercharger kit and have it run fine with stock programming? I know most supercharger kits include another fuel pump to bump up pressure under boost, but how does the cpu not crap itself when is sees all this extra incoming air, while as far as the cpu knows it's still only supplying the stock amount of fuel for an N/A application? Does the computer just open up the injectors all the way and then the extra fuel from the supercharger FMU makes up for the extra incoming air?
Does the computer only pull out timing if it senses knock, so if there's no knock the computer won't pull timing, just stay maxed out under boost?

Basically I'm just trying to figure out how you can bolt on a supercharger kit and go?

Thanks everyone.

 

its not an exact science when it come to a supercharger kit "as delivered". The FMU has a predetermined "gain" like a 8:1 FMU (adds 8 psi fuel for every 1 psi boost). This is done the same way the factory regulator works by restricting the return line. Most "as delivered" FMU's are a ratio too high like 12:1 or 10:1 and this is to make it run rich for safety. Nitrous companies do something similar. The FMU is adding the extra fuel and the computer just goes on its merry way of running the injectors like nothing has changed for the most part. A properly tuned FMU works just fine if you can do it on a dyno using the proper ratio FMU, a vacuum/boost line restrictor orafice (to be determined on the dyno), and a vacuum/boost line bleed orafice (to be determined on the dyno) up to a certain HP then even the extra fuel added by jacking the fuel up through the injectors you have isnt enough. then to get bigger injectors you need a chip. I like to go this way a stock motor (305,350, crate motor) and a regular non race blower kit will work fine with the FMU when you move beyond those parts the FMU become obsolete for the most part.