Originally Posted by
crazycage
i would of thought it would be the exhaust ports that would need opening up first as the inlet side is forced.
Nope, opening up the inlet is exactly what you need to do! Very restrictive on the CVH head and huge gains can be had from correct porting of the inlet side.
Originally Posted by
B16CVH
No point really, the valves are already too big for a start, plus, the gas will always find its way out anyway.
Spot on there mate!
Originally Posted by
crazycage
i can see what your saying but the exhaust side will choke before the need for ported inlet and bigger inlet valves but thats just from my own experiences.
Not on a CVH head mate, the exahust side is not restrictive and will flow till the cows come home! lol
The only part of the exhaust side that eventually becomes restrictive is the turbine wheel and that is why you then fit a bigger one (Stage 3 T3 has .48 for example), or fit a bigger turbo all together (like a T34).
Originally Posted by
crazycage
the way i see it is you are forcing the air into the engine with your turbo so you wont see as much of a gain on the inlet side as you would on the exhaust side,and the quicker you get the gas out the quicker you can start the process all over again.
p.s im no expert tho.
You will see a huge gain, by increasing flow your boost pressure will drop as will your ACT's meaning you can make more power easier (less chance of det).
On CVH heads the Inlet ports are opened up to match the valves and the exahust ports are only polished if touched at all (helps the gasses escape easier by reducing friction) most are left unmodified because they are already way over spec'd for the engine and can quite happily flow
over 250bhp's worth of exhaust gasses. In fact IIRC the flow limit of the exhaust ports and manifold has not been reached yet.... but dont quote me on it!