1mm O/S valves

[Steve885]

Has anyone gone this route ? Was there a noticeable difference..

 

[Galantvr41062]

I think most high HP builds, 600+ AWHP have 1mm over intake and exhaust valves. Just putting in 1mm over valves with no machine work to the head will hurt flow, and HP/torque. But if the valve seats are cut to fit over sized valves and the port work is matched and your setup will support it I think its a good idea.

~John

 

[Steve885]

Sorry should of explained my self..I'm in the process of replacing all valves due to a timing misshap..the heads going to the machine shop Monday. Just thinking of how I could put every dollar I have into this f#%*ing car

 

[Galantvr41062]

what is the current setup? future plans/goals for the car. I know a lot of people my self included that has gone plenty fast and made good power with stock valves.

 

[TomN]

If your replacing the valves anyways then yes have 1mm over put in.

 

[5OF2k]

You dont need OS valves, at all. Keep the stock sized valves and go flatfaced if you want a benefit in power. Also, be sure the machine shop grinds the seats and faces at 5angles and for a turbo setup. Ive seen machine shops grind the faces of turbo valves to NA spec, and you'll burn right through the valves.

As a for instance, my old built head from one of my last Talons is now on my friends car. By built, i mean crower springs/retainers and flat faced factory-spec cut valves BTW. Anyway, his car makes 790AWHP at 40psi on a bigass BW snail.

Oversized valves are not necessary, and could actually decrease efficiency dependant on setup, especially for a street car. The heads on these cars are capable of handling a lot of airflow from the factory. A LOT.

-Jake

-Jake

 

[Steve885]

That's the answer I was looking for...thanks