Operations

Just thinking out loud, seeing that this performance update is for the 15/16 year models, seems that this programing is intended to address issues that GM addressed in the 2017 pertaining to the supercharger lid/bricks.

Of course it does not fix the high inlet temps, but higher octane with revised tuning would seemingly stop or reduce timing being pulled under track conditions.

Knowing GM, they found a way for the customer to pay for a fix by wrapping it up in a upgrade package.

Just sayin...

tail_lights

Good point.... Interested in results!

SgtC6

Quick update. TCSC has located the tune but won't released it without an authorization code. So now trying to get that straight.

SBC_and_a_stick

I also wonder if it actually runs more conservatively on 93... Running 91 with it could also be a way to void warranty.

In a way I don't think there is a choice. In my experience, the car requires 93+ on track to run without hiccups. By that logic we're already paying for it.

Hard to know what the tune does. Hopefully some of the better tech guys on here will break it down into its basic functioning for us.

Bad Dad

Higgs Boson

If I can get my hands on the tune I will compare it....My Z is at the dealer now actually getting a couple items addressed so I will ask them to flash it with this tune (if they will do it free).... Otherwise, I am sure a copy will pop up on the HPT tune bank eventually.

Many times GM makes changes that are not visible in the traditional tables in the tuning software though so there's a chance we won't "see" anything at all.

Talking about spark, etc is all speculation at this point. Based on the description, the only changes I would expect is an alteration to the IAT Spark Modifier table so it doesn't pull a bunch of timing when IAT gets hot....something I already modify in my base tunes.....

If that's the case, then the 100 octane requirement for track use is a safety precaution to stave off real heat induced knock and for normal street driving you actually could run 91 and be fine.

We will see.

BLKTA

I think this is pretty cool on GM's part to offer this option especially for the LT4. Almost all 100 unleaded racing gas is clear with no ethanol, so right there it will run richer (assuming they don't change stoich) which in turn will help keep combustion chamber temps down (especially nice in hot weather). I would guess they will add WOT timing which even 2 degrees should pick up 20 hp on a SC motor. Either way, curious to see the tweaks and results.

Higgs Boson

When you say ethanol free gasoline "runs richer" what do you mean?
When you say "as long as they don't change stoich" what do you mean?

Stoich is lambda 1 no matter what fuel you have in the tank so "changing stoich" in the tune will only change fuel trims, not lambda.

Last time I checked, E0 is 14.7:1 Air:Fuel Ratio and E85 is 9.85 Air:Fuel Ratio. When you have more air per part of fuel that is leaner, not richer.

GSpeed

We did all of our baseline dynos today, downloaded the factory tune, and have submitted the Vin and mileage to our local dealer. Currently have the work order at the dealer and they are working on making it all happen. Will
Provide all the dyno, tune, and logs as we get them!

Car made 520-528 5 hot pulls in a row.

Operations

Thanks, Good to know

JoesC5

E10 is 14:1 Air:Fuel Ratio and I understand that is what the C7 is tuned for, whereas the C6 was tuned for E0's 14.7:1.

What happens when you run E0 in a car that is tuned for E10?

GSpeed

Minimal, from a math standpoint. It's 3-4% difference in fueling. Something to disregard? Not really. Will it affect people with this calibration? Probably not.

JoesC5

What would happen in the real world?

If you did a 100% pure stock C7 pull with E10, 91 octane, and then drained the tank and put in E0 91 octane and did a pull. What would the dyno results be?

GSpeed

3-4% richer. Maybe 10hp. However, part throttle fuel trims will pick it up, and make the change. Once the Ecu learns, it will be a wash.

BLKTA

That's what I've seen when running clear gas and what I was referring to when I said it will run richer.

JoesC5

What I'm having trouble understanding is if the computer is constantly adjusting to have the engine run at 14:1 A/F ratio and then you put in a gas that delivers it's highest power when running at 14.7 A/F ratio, how does the computer know that. It seems to me that the computer would always be adjusting the A/F ratio so that it's 14:1.

What am I missing?

jbsblownc5

Very interested to see the results of the 100 Octane tune, I will certainly do a bunch of dyno testing once my car comes in...

Running Alky/meth injection, and Torco with the 100 tune, might be the ticket to not losing the warranty and still bumping the tune/HP. Throw on the ram air Halltec, already sitting on my garage floor, and this car will pull nicely!

Again, I'll ease into things on the dyno with HP tuners, checking for knock as we compare tunes...

Higgs Boson

It doesn't run richer, it runs the exact same just with positive fuel trims. Positive fuel trims means it is lean.

johnglenntwo

I recall it started with an original Halltech, and A&A was involved. A EFILive owner ended up testing 100oct and Torco, as I recall. He was able to turn smoothing off. He was into it, hence, I picked up his terminology: happier engine.

And No! Torco is obvious, and they could probably find remnents in your oil from the alcohal as well.

Or if you grenade your motor just make sure you have used oil not contaminated for after you flush it out, and have left the junk all in tact.
​​​​​​

Dave Schotz

Did you dyno with 93 or 100 in the car?. Will be best to see apples to apples with same fuel.

Best Regards,
Dave