Hey guys has anyone ever heard of machining the stock twin cam heads for bigger exhaust valves? I've read quite a bit about building engines lately and haven't come across anyone mentioning this.I talked to a local Indy the other day and he said it helps with the heat and that the twin cams have smaller exhaust valves than the old Evo's did.Just checking around to see if anyone has thoughts on this or if you've ever heard about doing it.Thanks.

 

there is a whole lot of science behind it, most of which eludes me.

smaller valves can contribute to higher velocity--- exhaust tuning can REALLY impact the intake charge velocity and the density.

the evo combustion chamber was a different shape so larger valves may have made more sense there ( another interesting evo thing is the discovery that a rough wall on the intake actually contributed to higher flow numbers than "polished")

so larger valve may be a gain in the proper circumstances and as part of a complete system ( incl. cam specs)

mike

 

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