kidkutz

Was thinking of using 0.5mm over valves...is it worth the machine work to put them in?

PrecisionH23a

i was told that on a turbocharged application you will compensate your lower end power but gain a little bit of top end power from the o.s. valves. On my h23a i was told it would not be that benificial, but o.s. valves have to do something... feel free to post some info on this topic, im curious about the exact pro's and con's of having os valves are

2K_TEG

In some situations an oversized valve actually hurts performance -- Joe Alaniz.

93LSivic

From what Ive heard on the LS motors is that only .5 oversize on the exhaust valves seem to be good. Stock on the intake. But this is just what I heard, and Im sure H motors might be different.

RCSIVTEC

i would go with a 1mm oversized but you have to use the right combination for the intake and exhaust. remmber if you have alot of air comming in you also have to have a lot of exhaust comming out to.

kidkutz

why would you go 1mm over?

so what you're saying is if you go 1mm over on the intake...go one over on the exhaust as well right?

RCSIVTEC

i would personally go 34mm intake and 29 mm exhaust thats if you running on a vtec head. that should give you all the flow that you will ever need. use ferrea superflow valves a bit more expensive but you get what you pay for.

trbob16a

This may be a dumb question, but are there any issues with running larger valves and having them not fit into the valve cut outs on the piston? I haven't measured mine because the block is 1200 miles away, but I was thinking about claying the motor just to be safe. I have 1mm over with arias 9:1.

RCSIVTEC

i only assume when you are running larger valves you have to take into account the valve size cut on the pistion. everything has to measure extaclly so it can work in harmony