OHC(also DOHC) and OHV, whats the difference

[pdubbs]

Originally Posted by Shev GTR XU-1

VVT, VCT, VTEC, its all very similar, ultimately varying the timing of when the valves open and close. Either by varying the cam, or somehow varying the valves in relation to the lobes on the cam, which I'm guessing is thru the system of 'dynamic vavle timing'.

I'm pretty sure OHC type setups still use rockers, while I agree its way better to have the lobe in direct contact with the valve (ie, no rocker), and also agree yes they would use that on more full house race engines, as it should be able to rev higher.

SOHC in a V configuration still uses rockers - DOHC generally does not, because you have the cams directly over each cylinder, making rockers unneccesary (cam lobes will drive valves directly with only a shim to seperate the two).

Can you post more info on the valve timing technologies discussed above (VVT, VCT, VTEC)? Very curious about these, my ride has VCT but I'm not sure what that means.