Inline 4 cylinder comp motor

[SSDiv6]

Originally Posted by RJ

For those that run them, what is the biggest issue facing a inline 4 cylinder comp motor? - vibration?, spread between intake cycles?

I see some with IR setups?, and some with plenums?

Thanks

Due to reversion at the higher RPM ranges, caused during the overlap event as it takes place on inline 4-Cylinder engines, the IR setup is more suited to making power when compared to a plenum. I cannot find all the data I accumulated in the past; many years ago, however, the reversion issue was a detriment for power to the extent I could see atomized fuel coming out the stacks of the Weber carburetors at high RPM.

Intakes with plenums required very shallow floors and a lot of work to make power, however, they did not make the power of an IR setup. Also, the lenght of the intake is very important. We built intakes with an aluminum base for the engine and another for the carburetors. For runners, we used hose for Turbo applications with clamps at each end so we could change the runner length easier.