Quote:
Originally Posted by Eldi Z
Thanks for the information Cjperformance and ZchU about your experience with the PC Canned (S**t) tune. Bottom line: Never use canned tunes, only dedicated ones which are written by a tuner on your engine - probably no way around it.
Seems like the P1X with the Stg.2 FMIC + LT4 fueling + Professional Tune, is the right way to go for a fun street car.
One more question: What is the advantage of using a 3 Bar MAP ? Why is a breakout harness necessary ?
I am learning a lot here... :-)
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I think you only need LT4 fueling above 580 RWHP, but a good idea if you plan on going over that at any point. More specifically, my understanding is if your injector pulse width is over 5ms.
1 Bar = around 14.7 psi, which is also atmospheric pressure, so a 1 Bar can not measure boost. For example 7 psi of boost is actually 21.7 psi (14.7 ambient + 7 psi boost) or 1.5 bar. Basically the tunes that dont use a 3 bar are fudging the values, or faking it. That's my technical explanation.... just faking it. I'll explain more when I understand it myself.
The breakout allows you to measure atmospheric pressure outside the pressurized intake tract by adding in another map sensor. One outside the pressurized intake tract to measure atmospheric pressure, usually your old 1 bar, and another (usually the 3 bar) to measure boost (or vacuum for that matter) in the intake. This allows correct calculation of the pressure ratio which is dividing the intake pressure by the ambient pressure (or vice versa maybe).
For example, 21.7 intake press / 14.7 atmospheric = 1.47 pressure ratio, which affects VVE table calculations (or lookups....) . Again, at least that's my understanding. If I'm wrong, please correct me
