Contour Enthusiasts Group Archives Forums Modifications Duratec Performance ported and polished heads

As with all intake upgrades,test data is the true way to see any improvement and even that can be misleading.For example, a baseline test of a port /valve flow rate on a Flobench Vs the upgrade may show greater flow but the dyno could show low or no gains.This is where velocity Vs volume vs turbulance come in.A lot of engines perform worse if you polish as they need the tubulance to get better cylinder filling etc.Its not 'one thing' its a series of actions that improve the charge and the quality of the charge entering the cylinder.