Nistune Forums

Hmmm ... maybe my VTC is not working on my RB25, since when it makes such a difference I should really feel that while driving.

On Z32 it is 10 degrees!

Funny thing anyhow, since IMHO more overlap is bad for torque.
If you want good low end torque you have as little overlap as possible.

Maybe with a turbo engine this is different, but usually a lot of the fresh mixture escapes through the exhaust-valves
when you overlap at low rpm.

Good nite ..

PL wrote:All SR20's are 20 degrees. Not sure on the other engines cos they're not really my thing...

PL

Easy to tell. Unplug the VTC solenoid and go for a drive. Without VTC it'll drive like a laggy slug (assuming your're starting with std cams and sprockets).

Workshop manual shows R33 RB25DET as 20 crankshaft degrees too - so Z32 must be the odd one out at 10.

Advancing the inlet cam has always given midrange improvements on engines I've dealt with - be they SR20DE or DET. Same deal on RB25DET. I've spent quite a bit of time investigating this. My theory is that they run minimal overlap std - so you can increase this quite a bit before you get any appreciable negative effects.

PL

i have mine working all fine with vtc.... but still can't find time to put it on rollers

but will do so - asap

with vtc sol OFF - it's not the same car no chance to miss it out....

bit too late... but got it checked.

first run : stock boost VTC sol. off
second : same but with VTC ON
fird - 11 psi ign not touched. ( AFR 12.0 all the way ).

Very interesting, which run is which (colour?)

Could you post this in a larger size/resolution?

look at the "bank" and HP on y axis

on stock turbo and stock actuator - it's crap on the top

Thanks,

Now it's clearer

Interesting,

I always thought there was a point when VCT would be detrimental to power output. (at high RPM)
Assuming VCT is on all the time (in the RED) it looks like VCT could be left active all the time anyhow???

Is this Dyno meassured 'at the wheels' or 'at the clutch'?

secod run VTC on - i meant working as standard or almost as standard ( can;t remember now what was it set up to shut off ).

it's engine power.

cheers.