FI VE question..
11-13-2006, 03:41 PM
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FI VE question.. Now, anything over 110kpa is supposed to be positive pressure in the intake, right? Now, one would assume with possitive pressure that the engines VE would be over 100%? Am I wrong for thinking about it like this? I did some logging and even at 10psi (165kpa), I still only have about 95% @4k RPMs per the AFR error % to the VE table.
11-13-2006, 04:20 PM
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No, the VE is the "fudge factor" to make mass of air
= MAP*RPM*IATmumblemumble*VE come out right.
The MAP reading ought to account for all the boost
effects. Presuming it's not pegged which I gather it
isn't, in your case.
Heavy boost would make for relief on the intake side
but the turbine on the exhaust stacks pressure up, so
maybe 95% is not too unreasonable (100% would
be both ideal extraction and filling).
Given that it's really just a fudge factor (table), all it
needs is the right answer out the back (actual AFR =
commanded) to call it "good enough". As long as you
believe in the fueling model anyway.
= MAP*RPM*IATmumblemumble*VE come out right.
The MAP reading ought to account for all the boost
effects. Presuming it's not pegged which I gather it
isn't, in your case.
Heavy boost would make for relief on the intake side
but the turbine on the exhaust stacks pressure up, so
maybe 95% is not too unreasonable (100% would
be both ideal extraction and filling).
Given that it's really just a fudge factor (table), all it
needs is the right answer out the back (actual AFR =
commanded) to call it "good enough". As long as you
believe in the fueling model anyway.
11-13-2006, 04:50 PM
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thanks for the answers. I just loaded the new VE and its just what I need it to be.. 14.7 at all but boost (except when I let off the gas and the MAP sees 15kpa.. I cant get it to budge from 11.x 
) and WOT is ~11.6.
This stuff is easy once you grasp it.
) and WOT is ~11.6.This stuff is easy once you grasp it.