Re: Turbo Tuning

["TK" <terryk@foothill.net>]

----- Original Message -----
From: turbo31 v6 <turbo31v6@hotmail.com>
To: <gmecm@diy-efi.org>
Sent: Tuesday, April 18, 2000 6:31 PM
Subject: Turbo Tuning


> Let me first say where my brain resides, I understand GM digital fuel
> injection systems including sensors and controlled devices etc.  I also
have
> a good background in engine mechanics rebuilding stock and high
performance
> engines.  I also use and comfortable understand hex and decimal reading
> systems for our bins, being able to make changes and burn the EPROMs.  I
> Also understand GM calibrations (that was fun) regarding tables, calcs and
> usage strategy.  The tuning tips provided by such great guys such as
ECMNUT
> and Bruce P were excellent reading and helped fill the gaps as well as
> confirm previous areas of understanding.
>
> Now, the work that I am doing (and I feel that my ground breaking and
> learned results shared with the list here will help enlighten many who are
> coming up the ranks of being tuners) is to change the tables in my bin to
> accommodate the mechanical and external changes done to this engine.  I
have
> a set of high performance aluminum heads, more aggressive supposed
computer
> friendlier cam upgrade, 29 lb injectors and a 39 lb hr turbo, low
> compression pistons and a well done performance rebuild to the rest of the
> engine.  I will run pump gas for now but 100 octane will later satisfy the
> need for more speed, later.
>
> The good news for those willing to help me is I know the locations of all
> fueling and timing tables and calcs as well as single items such as
> disabling EGR etc (big sigh heard ;-).  So, with EGR, PE, AE, Purge, Boost
> mult tables (no boost till VEs done) and associated flags disabled, on to
> the work.  Right off with the large injectors, the stock turbo chip will
> need to be re-worked, and the claimed single values for injector rating
> GL/HR single injector flow rate and SEC/GM product of injector flow rate
and
> fuel calculation base constant for single fire were changed right off with
> little help at all.  Now the change for GL/HR was easy to convert but,
> SEC/GM? I assume seconds/gram of fuel (what)?  Taking this number down
> accordingly to the injector size increase did not help and I may try to go
> the other way (increase).  Next is the infamous VE tables, 3 of them, F29
> (TPS >/= to 2%) base VE for 600 to 4000 rpms and vac to boost load ranges,
> cool.  Then the F29 Extended table for TPS < 2% good again.  Now knowing
the
> big F29 is for main driving and the Extended F29 for fine tuning idle fuel
I
> am left with..F30 VE vrs RPM for?  For this table, RPM is below idle to
near
> read line and is a one liner (not 3D table) that I am not sure how to use,
> and which VE first to tune.  Can it be that the F30 is a bulk change
(maybe
> get the injectors closer right off?) and the F29s for the rest?
>
> Thanks for all the help in advance.
>
> Jesse
>
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