I am still working on ways of fitting a GSI 4 branch exhaust manifold to an ecotec (cheaply) and think I have just about got an easyish way of doing it.
Before I go much further does anyone have any Idea what the gains in bhp should be from doing so?
Interestingly, the port spacings are just the same on the ecotec head to the c20xe but the stud centers are totally different ;(
From the pic you can see that the kidney shaped head ports also have another hole which is meant for the egr system (not used on my c18xe) so I intend to ignore these and assume the ports are sized to the engine and these if blanked by the manifold and gasket from the GSI mod will cause no ill effects.
The lambda probe hole on the manifold is M16, anyone know the thread pitch to save me measuring as I have to make an adaptor for the manifold I am using (it doesnt have one)