(ot)i realyy hate to ask this ? here but.... VTEC explained

[LXVTEC@aol.com (LXVTEC@aol.com)]

Vtec does control the duration and lift of the cam but not the way you are 
thinking. the Cam or cams has 2 different profiles on the cam. on SOHC it 
controls either 1 or 2 intake valves depending on VTEC (2 intake valves)or 
VTEC-E (1 intake valve). on DOHC 1 cam controls the intake and the other cam 
controls exhaust valves. On certain motors they open at the same time. on 
other motors (Prelude and NSX) they open at different times. 

The way VTEC does this is by using oil pressure controlled by a VTEC solenoid 
which when activated slides a rod into the rocker arms so the valves use the 
higher profile.

So VTEC is basically haveing a low profile cam and high profile cam at the 
same time at different  RPM's and the switchover point is usually around 4400 
RPM's

Masun Dixon
78 Scirocco 16V
87 Scirocco 16V