I'm going to be swapping out my cam soon and I want to know how can a prom make you car run smoother and more powerful? I know if you lean out the fuel a little that gives you better power and gas mileage. How does it make your car run smoother? Or am I wrong and it will not help my car run smoother after the swap.

The car is a 91 z-28 350 auto and the cam is a zz4.

Thanks.

 

The oem calibration, is purposely sloppy to allow for variances, in quality control (actual engine building), and driving for 100K miles.

Optimising it for one particular combination, can't help but to be better. Trick is just learning and experimenting.

 

Yeah i understand that. But I just cant figure out why it will run smoother? Can you tell the ecm to expect less vaccum or am I totally off?

thanks

 

my take on adjusting for a longer duration camshaft would be add more spark advance down low in the RPM's to make up for lower cylinder pressures.
The factory settings are already too rich, so no real need to go richer.

You would actually need to lean out the lower RPM range under light & low load conditions because of decreased vacuum like you say.
Well that's my 'guess'

 

evilho,

If you get a chance read through the 'P730' post below on tuning the fuel curve.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org