If I change the cylinder volume for a 427 from a 346 will it make me go lean or rich?
02-11-2012, 11:00 AM
#1
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If I change the cylinder volume for a 427 from a 346 will it make me go lean or rich? My car was tuned a long time ago but I noticed the cylinder volume was still set using the 346. I wanted to know how to adjust the VE table. Thanks
03-01-2012, 09:44 AM
#5
I was under the impression that it was taken into account at least on ve calculations. I remember GB talking about changing it rather than rescaling injectors in his dvd when trying to avoid some limitation in the ecu. Disclamer: never tried it, just what I recall from the Banish dvd.
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03-02-2012, 07:56 AM
#8
I was under the impression that it was taken into account at least on ve calculations.
Theoretically speaking, increasing cylinder mass would predict more air being moved, thus add more fuel.
03-02-2012, 10:53 AM
#9
Apparently it depends on the ecu. Got confirmation from GB that in some earlier years where the ve table is in percent ve rather than gmve it is a critical part of the calculations. When they switched to gmve it became obsolete and was thought to no longer be a part of the calculations.
03-02-2012, 02:46 PM
#10
Looks like the first year I could find for the switch was 2005. From GB's description, the units in VE on the old system were in the 100's with the %VE tables (where cylinder volume matters) and then the GMVE numbers are in the 1000's (where cylinder volume is no longer important). So hope that clears this up for some folks.
Back to the OP, I am not sure what year ECU you have, but by them leaving the number at 346, that may be the tuner's method of scaling down the injectors in order to avoid hitting a hard limit in the ECU. You can probably tell by looking at the injector scaling.
Back to the OP, I am not sure what year ECU you have, but by them leaving the number at 346, that may be the tuner's method of scaling down the injectors in order to avoid hitting a hard limit in the ECU. You can probably tell by looking at the injector scaling.
03-02-2012, 03:54 PM
#11
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Looks like the first year I could find for the switch was 2005. From GB's description, the units in VE on the old system were in the 100's with the %VE tables (where cylinder volume matters) and then the GMVE numbers are in the 1000's (where cylinder volume is no longer important). So hope that clears this up for some folks.
Back to the OP, I am not sure what year ECU you have, but by them leaving the number at 346, that may be the tuner's method of scaling down the injectors in order to avoid hitting a hard limit in the ECU. You can probably tell by looking at the injector scaling.
Back to the OP, I am not sure what year ECU you have, but by them leaving the number at 346, that may be the tuner's method of scaling down the injectors in order to avoid hitting a hard limit in the ECU. You can probably tell by looking at the injector scaling.
e.g. HPT displays the 1998-2008 GenIII VE tables in % units, EFILive can display the same years as either % or g*K/kPa (aka gmve).
In any of these tunes if you change the cylinder volume parameter, there is no change in fueling that can be seen on a running engine.
03-02-2012, 04:32 PM
#13
Like I said, just what Greg Banish said...he has WAY more experience than I do, so I listen 
http://www.hptuners.com/forum/showthread.php?t=38034
It plays a HUGE role on determining cyl_air in speed density on the older systems. Newer systems retained the value for reference as a placeholder, but it really doesn't do anything. The way to tell is check and see if the units in your VE table are "% VE" or "GMVE". The older %VE (numbers typically 0-100ish) versions must multiply by the cylinder volume to get an actual airmass. When they switched to GMVE (numbers 1000-2000ish), the volume got baked into the numbers in the GMVE table, so the reference value scalar became redundant as far as fueling is concerned.
