DDgonzal

Hello there

Ok, you are right the Honda VTEC system increases valve crossing with the increase in the RPM. However, I think (maybe I am wrong) that the VTEC system doesn't advances or retard the camshaft gears. The VTEC system is DOHC and instead of having one came for each valve it has 2 (or 3 on the S2000) came for each valve, with increasingly higher and sharp dimensions. The came movement is transmited to the valve by 2 (or 3) special rockers (I think this is the name for it). When the oil pressure is low only the first rocker is activated. If the oil pressure raises a litle more (higher RPM) the second rocker will get conected by a moving pin (activated by oil pressure) to the first rocker, so the higher and sharper came is controling the valve. If the system has a 3rd came then its rocker is going to begin to work at even higher RPM.

Some other cars have fase variators (is this correct?) and those advance and retard the camshaft gears.

However I was asking about the A12 engine, since if you have only one camshaft you can only retard or avance all the valve cycle and you can not change the valve crossing (because this is determined by the came position on the came shaft).

Thanks

Ricardo