AFR/Lambda question

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05-23-2020
jaydubb71

AFR/Lambda question

Greetings.

On the GM DI (Direct Injection) side, we tune for .85 Lambda (~12.5 AFR based on 93 octane with 0% Ethanol/14.7 stoich) WOT on boosted applications (1.176 EQ Ratio). Does the VR30DDTT like the same AFR/Lambda? If so, the factory tune is SUPER RICH. I've been lurking on the JB4 forum and Burger targets 12.5 with their fuel wires (I will be glad when EVERYONE speaks Lambda...). I honestly dont like how they accomplish this. Reminds me of the early days when we used resistors to fool IAT sensors (tricking the ECM into adding fuel and timing) and MAF translators. And it looks like the timing curve is VERY conservative. I really need to see the KR PID. As soon as I get some "supporting mods" installed on this thing, Im digging into the tune...
05-23-2020
evan.s@hptuners

Quote:

Originally Posted by jaydubb71

Greetings.

On the GM DI (Direct Injection) side, we tune for .85 Lambda (~12.5 AFR based on 93 octane with 0% Ethanol/14.7 stoich) WOT on boosted applications (1.176 EQ Ratio). Does the VR30DDTT like the same AFR/Lambda? If so, the factory tune is SUPER RICH. I've been lurking on the JB4 forum and Burger targets 12.5 with their fuel wires (I will be glad when EVERYONE speaks Lambda...). I honestly dont like how they accomplish this. Reminds me of the early days when we used resistors to fool IAT sensors (tricking the ECM into adding fuel and timing) and MAF translators. And it looks like the timing curve is VERY conservative. I really need to see the KR PID. As soon as I get some "supporting mods" installed on this thing, Im digging into the tune...

Yes the factory tune is very rich and these things love timing increases. When we were doing testing there was a pickup of something like 30-35whp alone on just timing and fuel changes alone, before we started testing boost changes (on an SS though, YMMV).
05-23-2020
jaydubb71

Quote:

Originally Posted by evan.s@hptuners

Yes the factory tune is very rich and these things love timing increases. When we were doing testing there was a pickup of something like 30-35whp alone on just timing and fuel changes alone, before we started testing boost changes (on an SS though, YMMV).

How lean did you all tune for during testing?