Hello, im building a 600-700whp h22 and i am trying to figure out what size valves I should use. I want this configuration to work and still be able to drive on the street occasionally on low boost so I dont want to loose low end if i go to big on the valves. If anyone has made this kind of power can someone let me know what your head setup is.

 

standard valve size has worked well for me

 

well i know the stock will work, but Im able to machine anything to make it work and I have already over bored it so I might as well go bigger valves, but like I said I want to get as much power as I can without losing low end. Anyone use oversized valves in there h22 boost set up? if so did you replace the seats?

 

i run stock size.. sorry

 

just because you can make them bigger doesnt mean they need to be bigger.

you have A LOT of variables and unless you can figure it out yourself, i suggest you talk to some of the machinists on here.

MAX_CFM
Combustion Contraption
DonF
...etc

 

well if there are some machinists out there that would like to answer this question and make it easier for me please feel free. thank you

 

alright, I called some machine shops and these are the answers I got, stock valve seats dont have to be replaced, but if you use skunk2 cams you can only use stock size valves because they might hit each other, if you use stock cams you can go the full 1mm oversize just on intake side. now I need some opinions. stock cams oversized valves? skunk2 stage2 turbo cams stock sized valves? which would make more power through the whole range?

 

I would just do the 1mm on intake use stock cams or have some custom grinds done to your specifics. Your talking 50whp to 150whp over what Im running now and my car is not very streetable the way it is. Im on stock cams springs also.