Increasing valve diameter

[Arctc Wolf]

I've been thinkin about everybody doin head work and getting huge cams and stuff. Why use higher valve lifts to get more air into and out of the cylinders when u can get extra air in using a bigger valve diameter on the intake and exhaust valves? now that overbore pistons r available, there's even more room to put in bigger valves. Why don't people who P&P heads increase valve size also? We could use less lift or less duration to make the same power, and have better chances of passing smog.

[pgriffith]

IF you increased the size of the valve do they have to machine the head to work with the valve? I also think its a good idea and valves areent too expensive and would be easy enough to do if you had the heads off. This is a good idea I think. I know Tom at supersix offers larger valves for the ford 3.8 im sure he could do something to our 3.8's also. Has anybody looked into this?

[Dominic]

zzperformance goes through fastbikesusa to have their headwork done - its astonishing quality. They do oversized valves. You're looking at around a 10% gain for every 0.2" you can get out of your valves... maybe 20-30hp if you can get the intake opened up nicely [img]smile.gif[/img] I doubt you can go past about 1.95"

[Arctc Wolf]

they don't mention that their valves r oversized. r u sure?

[Zooomer]

We run 1.88 valves on the intake and 1.57 on the E. We did this mainly to enable a Serdi continuous angle radius on the seat.