Originally Posted by YeaItsAFourDoor
So Ivtec is Vtec and VTC combined? Oil pressure of course is what helps start it but I-vtec is the advancement and retardation of the intake cam to adjust overlay and such for fuel economy and power along the band? Vtec is just the oil pressure causing a different set of cams to open and close the valves faster and long and VTC is the variable cam timing? Please correct me if im wrong...
1: at the right RPM, the ECU sends a signal to the VTEC solenoid to open up and allow the locking pin to engage.
2: once open, the oil pressure is high enough to push the locking pin and engage the rocker arms related to the VTEC cam profiles.
3: the cams are a solid piece of metal that does not move vertically or horizontally, it just spins. the profiles of the cams (aka cam lobes) pushes down on the rocker arms, which pushes down on your valves.
4: the VTEC cams have two different profiles on them: one for non-vtec and the other for vtec. these are always spinning together and pushing on the rocker arms. the vtec rocker arms are not pushing down on the valves until the locking pin is engaged.
5: iVTEC has a better ability to control ignition timing. this has nothing to do with cams and its profile. the retarding and advancing is just when the spark actually ignites the fuel mixture. retarding means the spark ignites the mixture after the factory adjustments, advancing means the spark ignites before the factory adjustments