my headswap car put down 279/314, with stock exhaust manifolds, a light cleanup job on the intake side of the heads, stock valves, and no tune
his car put down 20 more hp with oversized valves, LT headers, and a tune. Its very believable.
Theres a couple Stock PI motor, non headswap cars, putting down 300+rwhp with the stock PI intake, cams and bolt ons. This of coarse, is with stock PI heads.
No there were no PTV issues at all. Actually you can some clearance becuase the oversized valves are flat faced as compared to the stock valves that have a protuding ring on the face. On the other side of the coin the distance between the valve and cylinder wall is decreased but I havent heard or seen any problems that could be directly linked just from having oversized valves when nothing else was changed in a setup.
No there were no PTV issues at all. Actually you can some clearance becuase the oversized valves are flat faced as compared to the stock valves that have a protuding ring on the face. On the other side of the coin the distance between the valve and cylinder wall is decreased but I havent heard or seen any problems that could be directly linked just from having oversized valves when nothing else was changed in a setup.