Auto VE = 120%

[L31Sleeper]

After a few rounds of Auto VE I'm starting to see almost 120% in some places
with supporting numbers all around them 110-118. It's in OLSD
Could there be something I'm missing ??

This is an almost stock L31 Vortec 350, K&N cold air kit, 1.6 rockers (OE is 1.5), modified throttle body.
I don't see why a NA motor should see over 100% ??

[5.7ute]

First up the VE% is only a calculation & not meant to be 100% accurate. However it is pretty close.
You would more than likely find that your Fuel model is wrong for your system. This could be something as simple as your fuel pressure is too low or dropping at WOT. Or the wrong injector data is in the tunefile.

[joecar]

Post log and tune files.

Set your VE units to g*K/kPa, then you won't be thinking in % anymore.

(You already know this: make sure fuel units are not Lambda).

What 5.7ute said... something else (injector/FPR related) is out, causing your VE to "correct" high...

With long tube headers it has been found that NA cylinder fill may be as high as 105-110% (just from the timing of the low pressure pulses "expanding" back up the primaries, and even a little higher that that at the tube resonant frequency... David Vizard has good reading material on this... he has found by experiment that the pressure difference across the intake valve [i.e. what causes cylinder fill on a NA motor] due to correctly designed headers can be upto 8 times greater than without headers (i.e compared to poor designed log style manifold... of course, the OEM LSx manifold designs are said to be fairly good, altho not as good as LT headers).

If you read the various papers you will find that LSx head design is said to promote very high cylinder fill (exceeding 100%).

[joecar]

BTW: long tube headers are a very good bang-per-buck with minimal wrench-turning, even on a stock motor.

[L31Sleeper]

Come to think of it I did change the injector package from the CPFI ( Central Port Fuel Injection ) a very bad system. To the MPI ( Multi Port Injection )
It is supposed to be a "direct" replacement.


http://contentinfo.autozone.com/znetcs/product-info/en/US/gps/800-1513N/image/8/