2015 c7 afr ?

[LS1408]

Anyone have any idea why the commanded AFR is going back to 14.11 at 5200 rpm? PE comes in and fuel goes to 11.9 until 5200 where the PE goes back to stoich. Here a scan showing a WOT pull. Thanks for any help.

This is with 7 psi at 5200rpm.

[veee8]

Hard to say without the tune. My best guess would be the PE torque threshold is kicking it out. Try setting it lower if so.

[LS1408]

Sorry here's the tune file. This is my first supercharged C7 so I have a few questions if yall don't mind.
Its making 7 to 8 psi with a A & A kit, what timing do these LT1's like with boost? I have 12* with 11.9/12 AFR now. Also its the 8L90 trans. Looks like 6th gear is the 1:1 gear. Is this the gear normally used?

[LS1408]

PE torque fixed that problem, set it to 20 all the way across.

[LS1408]

What timing is close on these cars with 8 pounds of boost and AFR? I'm at 13 degrees and 12.0 AFR now. it put down 560rwhp at that.

[SultanHassanMasTuning]

I wouldnt go higher on timing.

[LS1408]

I wouldnt go higher on timing.

Thanks, 12.0 about right on the fuel? It seems pretty happy there.

[LS1408]

Are y'all pulling these cars in 6th gear or a lower gear to keep the MPH down?

[veee8]

I pull them in 5th gear.

[LS1408]

Dropped timing to 12 and power dropped and graph looks terrible. Deff. seems to want a little more timing.

[mowton]

My rule of thumb is no more than 12 degrees at Max Pressure (Torque) and no more than 14 degrees at Max Horsepower.....Ring lands are the weak link...

Ed M

[veee8]

My rule of thumb is no more than 12 degrees at Max Pressure (Torque) and no more than 14 degrees at Max Horsepower.....Ring lands are the weak link...

Ed M

Same rule of thumb I go by......

[LS1408]

So even if the plugs and dyno graph show it needs more timing everyone uses a rule of 14 degrees?

[Ben Charles]

You spraying meth????
I tend to run around 13/14 degrees, but have used 16 on meth cars... Edelbrock and Maggie both setup there tunes to be around 15-16 degrees for what's it worth...

Lt4 (10.1 CR however) I've had good luck around 22 degrees

[Redline MS]

So even if the plugs and dyno graph show it needs more timing everyone uses a rule of 14 degrees?

rule a thumb is a good place to start but why don't you really try to find peak cylinder pressure (aka Spark Hook Test). Boost and spark don't quite go hand in hand. Its about charge motion which includes mass (volume) which has an impact on spark optimization. Edelbrock runs about 20 degrees on there E Force systems but an ECS system tends to like 15-16.

More importantly you need to get the fueling in line. This in theory seems obvious and easy but as I have stated a few times; charge motion into the combustion chamber gets all messed up when you start ramming higher then stock airflow which has a impact on the chambers ability to mix all the air/fuel. This is where injection timing and rail pressure start to get interesting. Once the mixture is correct only then should spark timing start to creep up.

[LS1408]

This is an A and A V3 kit with a 3.8" pulley. 16 to 17 degrees is what it seems to want. At 14 power drops off.

[Ben Charles]

I assume this is a 93 octane meth car then??? 3.8 pulley is good for around 600rwhp

[LS1408]

These engines require meth at 10 pounds of boost?

[Higgs Boson]

These engines require meth at 10 pounds of boost?

these fuel systems do, not the engines. mostly due to no available bigger injectors yet.

[SultanHassanMasTuning]

upgrade to LT4 pump and injectors