Tuning for Boost: LT1/GDI Motors Vs. LS/PI Motors
 

Trying to understand the differences in tuning the LT1 (High Comp.) in boosted applications (I.E. Centri Chargers) Vs. similar boosted setups on the earlier LS motors (I.E. LS3 or LS7). Talking about Pump Gas 91 and 93 applications.

What are the main parameters to watch out for in the newer LT1 GDIs?

A/F and Ignition Timing probably being the critical factors to take into account, however, the relation to Fuel pressure(I.E. much higher with the GDI motors?) and injectors' timing and fuel quantity / supply should be attended to in a different way I guess?

Thanks to those who are experienced can provide some education and guidance on how they go about safely tuning the SBE LT1 motors on boost.:thanks:

While there are plenty of guys on this board who know more about this than I do, I’ll get the party started by saying that in addition to AFR, you need to watch:

• Low side fuel pressure from the tank
• High side fuel pressure at the rail
• Injector PW time, I’d suggest keeping under 6.0ms

If any your fuel pressures drop below commanded, or injector PW goes over 6.0, I’d get that figured out before proceeding.

Thanks for chiming in. Lets see additional inputs from some of the tuner members. Specifically, in which areas the LT1 is different than say the LS3 when tuning for boost (I.E. ATI P1X based, Vortech 1500 based (ECS branded), Etc.)

The high pressure component is the big difference vs LS engines. You’re commanding around 2900 psi at WOT, and if that drops off your injector PW will get too far out. The injection window is more critical on the LT engines. Just because your AFR is good doesn’t mean you actually are... ;)

Exactly...injection timing is one of the most critical parameter on these DI engines.

Another thing is you will need to adjust your driver demand and torque limits.

Thanks for the inputs.
I guess that for added safety a HPFP (I.E of the LT4) would help with required fuel supply, in addition to strict adjustment of the injector timing?

LT4 in tank pump, high pressure fuel pump, and injectors are the bare minimum to enter the world of LT boost IMO. Desired power level, how much E you want to run, etc will determine what you need for fueling hardware. New XDI stuff from Katech as well as port injection setups mean the sky is the limit for all intents and purposes.

Good points. LT4 In-Tank, I already have from the factory (its an SS 1LE), so I would need the HPFP and LT4 injectors.
What about an in-tank pump voltage booster (AKA "BAP")?
My power goals are ~ 580 WHP, not more. I hope to be able to achieve it at ~ 8.5-9 Pounds max on 93 pump and still keep the timing advance and A/F in a "safe zone"
Is this achievable with I.E. a Novi 1500SL system?

That power level is achievable with any blower, frankly. If you tune your FSCM you will not need a BAP at that level.

Good to know. What is FSCM?

Are you referring to increasing the fuel pump voltage?

Fuel System Control Module, controls your in tank fuel pump among other things like AFM valves.

Yes

Can you tell me where the fuel pump voltage is in the FSCM? I have my tune pulled up and I see my AFM/NPP valve settings, so the FSCM is loaded. But System/General/Alternator - I see the "fuel system voltage min"...but that's in the ECM. as a matter of fact, everything under alternator is in the ECM.