What is it about big cams that our maf cars don't like. I know that map cars need vacuum readings to know how much fuel to supply the engine, and if the cam changes these vacuum readings will trick the computer, but what do big cams do to maf cars that the computers hate?

 

They change the air flow rate at idle. The LS1 guys just lean down the lower levels of their VE table so they get less fuel at idle and low speed.

Long overlap will increase air through the MAF at idle but a lot of the fresh air gets wasted out the exhaust, and some burnt exhaust gets back into the chamber due to reversion. The end result is too much fuel at idle.

The other problem is idle speed tends to fluctuate with a large cam and the ECM has the IAC going nuts trying to compensate. Reduce the effect of the IAC and idle will be more stable.

 

As long as your chip ain't stock, you can run as big a cam as you want.

 

i have a stock chip with svo injectors and comp cam 510/510 lift 220/230 dur 114 lsa good idle 600rpm