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Oversized valves on the street?

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Hey all, I'm trying to pin down whether it's a good idea to fit larger valves while I'm having my EVO head ported. The car is for the street, so I'm making sure mods I do, do not compromise the bottom end driveability too much. As such I'm using GSC S1 268 cams (3000 - 8000) rather than the more popular 272 sizes that everyone goes for. I am planning on stuffing 30psi through it though.


The head is going on a 8.5:1, 94mm stroker.


So the question is, will bigger valves and the porting to make them worth while, badly compromise the bottom end?


Experiences of anyone who has done this would be most appreciated.

ECM Link, 399 MAF, 560cc injectors, 270 cams, TD05-20G @22psi, 3" dump, full 3" mandrel exhaust, intercooler, Fidanza alloy flywheel, 4 bolt LSD, EVO IV brakes, Strut braces, coil overs and sway bars.



    Grumpy old man from the school of hard knocks

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Ive done the oversize valves in several builds and not had a negative on any of them.

  • ted likes this

Black evo 1 full road rego and done properly/legally

I have heaps of parts...but never the one I need.



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