4g63 t valve reliefs, comp ratio

[Woodduck]

Hi, does anybody now how much deeper valve cut outs are needed when adding a higher performance cam. (just a guide would be good. ) Just doing a motor and want to allow for developement later on. Motor is a 4g63t sohc 8v. Using Toyota 3sge turbo pistons. Pistons give approx 8.9:1 comp at moments, any recommendations on CR. will be running premium fuel. Thanks

[cheaterparts]

Hi, does anybody now how much deeper valve cut outs are needed when adding a higher performance cam. (just a guide would be good. ) Just doing a motor and want to allow for developement later on. Motor is a 4g63t sohc 8v. Using Toyota 3sge turbo pistons. Pistons give approx 8.9:1 comp at moments, any recommendations on CR. will be running premium fuel. Thanks

when changing cams and pistons it's worth dummy assembling the engine and doing the clearance checks

as for CR it depends on the cam you are using however as you are turboing the cam with more than likely not be a huge over lap thing with the valves a long way off the seats at TDC
most if not all Turbo high performance cams have little over lap and even longer duration cams have wide lobe centres to cut the over lap down

CR is also dependent on the amount of boost you wont to run -- if you are using an effictive intercooler or not

[Woodduck]

Thanks for the reply. I have already done a dummy assembly with the std cam and have about 2.5mm on the inlet and more on the exhaust. Just trying to get some idea how much extra I need to allow for a future cam upgrade. I will be checking the clearance using the dial method when I upgrade the cam but if I would like to avoid pulling off the head by giving it a little bit extra now. As far as boost I am looking approx 15 psi. We are using an aftermarket intercooler. The vehicle it is going in is a triton ute off road race car.(performance 2wd) The reason we a sticking with the sohc is because the shock, spring towers come up into the engine room making space a bit tight.