[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
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
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo@lists.diy-efi.org