I'm working on the tune for my 2007 TBSS that is going to get twin turbos. I just finished the return fuel system with -8 lines and dual Walbro 450 pumps in the tank, and I installed DeatschWerks / Bosch 95lb injectors. Other than a 4L80E running off T43 TCM with 2008 Chevy Express OS (and the above mentioned mods), the truck is essentially stock.
DW provides all of the necessary injector numbers, so I put those in the tune already. I've decided on a 50% scale, so other than flattening then splitting the IFR table in half, I've scaled all the tables I can find by 50% - modified the label axis when I could, everything else was multiply by .50. Here is a short list of what I've done so far:
Modified for 12592525 MAP
MAF table x .50
Cranking table x .50
VE Coefficients adjusted (all VE tables x .50 via "Virtual Volumetric Efficiency")
IFR set for return fuel system at 44psi (injectors flow 86lb/hr at 44 psi, table set to 43lb/hr flat)
Offset vs. Press vs. IGNV, Short Pulse Limit, Short Pulse adder, and Min Injector Pulse adjusted per manufacturer specs (nothing adjusted here)
Following spark tables "scaled" (multiplied all by .50 - not sure this is done right):
-Max Torque Timing
-Main spark (high octane / low octane / HO (DOD) / LO (DOD)
-Idle Spark Advance (Base / Coastdown)
-IAT Spark (Base / Base Hi)
-ECT Spark (Base)
-Cat Lightoff (Normal / Coast / Idle P/N / Idle Gear)
-Variable Cam Spark
-Flex Fuel Spark
-EGR Correction
Supercharger enabled, no TQ Mgmt
No boost yet, just the fuel system changes. The truck will start but it's not right. I'm not sure if I get the whole idea of scaling, regardless of the multitude of things I've read. I'm hoping someone can take a look at my tune (I also attached the base tune for comparison). Am I missing something?
Thanks in advance