I understand the basic way it works, but my main question is, does it keep the valves open longer or push the valves in further?
or both?

who just got vtec weeeeee it's fun





[Modified by One2hit, 9:03 PM 1/7/2003]

 

it varies both lift and duration. The entire cam profile changes, from overlap values to maximum lift and duration, as well as ramp rate.

 

ok...my engine is a SOHC

is there just one stage to it? like either on or off?

at what rpms does this happen

 

1) If it's an SOHC Honda motor, VTEC is only a a part of the intake valvetrain. The exhaust valves have a single cam profile throughout the RPM range.
2) VTEC is a single stage setup on all production Honda motors.
3) VTEC isn't an on/off setup, it's a big cam/small cam setup. It's not as simple as thinking that VTEC = Power, as what cam timing works best depends on the RPM and throttle angle you are at. This is why it was invented in the first place; to run smaller valve timing at low RPM and big timing at high RPM to maximize power output and engine efficiency over the motor's RPM range.
3) I'd need information about what vehicle you own to tell you at what point you reach VTEC crossover.


[Modified by texan, 2:37 AM 1/8/2003]

 

the engine is a d16z6 in a '91 hatch

 

If you're using a stock P28 ECU, the crossover to the VTEC lobes should be occuring at 4800 RPM. I'm not 100% on this though, so someone correct me if I'm wrong.

 

i have a basically stock D16Z6 in my '92 Si and you get the VTEC "noise" at exactly 5k rpm's. all that's done to it, is intake and exhaust.

i'm guessing that's when it engages. unless my tach is off. i dunno.

 

It is supposed to be 4800rpm but again mine tach reads 5000rpm when u here the chance. If i remember right that honda standard tachos read higher than they should 200rpm ish. correct me if wrong.

 

ok, I just had put a brand new clutch in, so I havn't taken it up to 5k rpms yet...O_O

must.......break........in

wtf is VTEC gonna do?? give me a boost??

 

...let 2nd gear wind out to 5k today....nothing happened o_o