[Nabush]

Guys,

It's for my vette but the same engine as your Gen6 SS, and there are more technical ressources here than in the Corvette forum

I just installed my American Racing headers and my AFE CAI on my 17 GS.

I also bought a wideband O2.

I'm running 13.1-13.3 AFR at WOT with the stock tune and 91 Chevron (probably close to 10% Ethanol)

Edit : After calibrating my probe, I run 0.88-0.89 Lambda = 12.5 AFR with E10 I probably have in the tank

Are my AFR safe to drive the car at WOT ?

I should receive my MSD Intake manifold in around 10 days and then planning to do a tune (dyno tune at JDP Motorsport, UT)

I'm also considering buying DiabloSport Intune 3 as it also to change fuelling and do custom tuning in the meantime if for you I'm too lean.

Thanks a lot for your help on that

[KingLT1]

Sounds a little lean. Ime you want to be around 12.8

[Nabush]

Originally Posted by KingLT1

Sounds a little lean. Ime you want to be around 12.8

Yeah I recall most dyno graphs I saw were a little bit below 13... but saw one or 2 just a little above 13...

[Poppacapp]

Originally Posted by Nabush

Guys,

It's for my vette but the same engine as your Gen6 SS, and there are more technical ressources here than in the Corvette forum

I just installed my American Racing headers and my AFE CAI on my 17 GS.

I also bought a wideband O2.

I'm running 13.1-13.3 AFR at WOT with the stock tune and 91 Chevron (probably close to 10% Ethanol)

Are my AFR safe to drive the car at WOT ?

I should receive my MSD Intake manifold in around 10 days and then planning to do a tune (dyno tune at JDP Motorsport, UT)

I'm also considering buying DiabloSport Intune 3 as it also to change fuelling and do custom tuning in the meantime if for you I'm too lean.

Thanks a lot for your help on that

You are a little lean. Try to stay out of the throttle until you get the tune.

[laynlo15]

12.2 to 12.5 would be a better number for your AFR

[dotfiles]

Why not just drive it conservatively until you get your MSD and custom tune? Should be fine at partial throttle but sounds a bit lean at WOT.

[T-Man]

That's perfectly fine. Anyone who says otherwise is still stuck with the PFI mindset.

[Nabush]

Guys,

We need to take in consideration the 91 Chevron I use can use up to 10% of ethanol.

Stochiometric A/F would be then 14.1/1

I switched to Lambda with my Bosh O2 wideband and I'm at 0.88-0.89 at WOT... Which should be 12.5 AFR with E10 (91 Chevron)

Z06 is around 0.85-0.86 with the supercharger...

I read everywhere DI runs leaner but by how much ?.... My 2018 Mustang GT with the new dual injection system runs 11.5 AFR at WOT @6000-7500 rpm and around 12-12.5 before .... which is very rich...

Thanks

[KingLT1]

I spend quite a bit of time reading literature on HPtuners forum. A few members over there have stated that 12.8 is a safe AFR for a naturally aspirated DI gen 5 engine running 93 octane. 12.5 is leaving power or the table, 12.8 is safe, 13.0 is ok, but 13.1-13.2 is getting a bit lean.

[Nabush]

Originally Posted by KingLT1

I spend quite a bit of time reading literature on HPtuners forum. A few members over there have stated that 12.8 is a safe AFR for a naturally aspirated DI gen 5 engine running 93 octane. 12.5 is leaving power or the table, 12.8 is safe, 13.0 is ok, but 13.1-13.2 is getting a bit lean.

Yes but AFR doesn't mean anything now since all fuel are E5-E10....
More and More tuners say " work with Lambda" instead...

Should aim for 0.85-0.88 Lambda...

[T-Man]

Originally Posted by Nabush

Yes but AFR doesn't mean anything now since all fuel are E5-E10....
More and More tuners say " work with Lambda" instead...

Should aim for 0.85-0.88 Lambda...

[Nabush]

Originally Posted by T-Man

Speaking of that, I used today C7 Afe Intake tune from Diablosport.

Still not totally relevant as I have LT headers also.

With this tune, Lambda is around 0.89 until 4000, goes up to 0.91 at 4100 then down to 0.87 then 0.85 at 6500. The car runs strong but I don't like this increase of Lambda at 4100...

Tried to add more fuel (+5%) , not a lot of effect... unless the feeling of less torque at low end if I go at 0.85 Lambda instead of 0.89....

When datalogging I see 0.5 to 5 degrees of Knock retard...but completely inconsistent..some runs I have almost nothing, some runs 5 degree mostly between 5000-5500 then it decreases.... Some runs it starts at 3000... Timing is high, between 21 and 26 deg...
Pulls in 3 rd gear show less knock retard than 2nd gear in average...

I read a HP tuner forums and it seems this engine has oversensitive KR sensors...

I tried something this night : copy the stock tune and rename it so intune sees it as a custom tune. then I added 5% of fuel everywhere. I will see tomorrow how it does.

Here are 2 logs 2 minutes apart...





Orange Knock retard
Pink RPM
Purple timing
Light blue : MAF
Blue: Throttle

First one I take 5 deg of knock retard
Second one I take only 0.74 deg of knock retard...

[Miami_1LE]

Originally Posted by KingLT1

Sounds a little lean. Ime you want to be around 12.8

What an idiot. Get out of the car game bro. 12.8 is leaner than 12.5. I'm hoping you made a mistake by writing that, if not and you think the higher the number means the richer the mix your totally wrong.

[6spdhyperblue]

Originally Posted by Miami_1LE

What an idiot. Get out of the car game bro. 12.8 is leaner than 12.5. I'm hoping you made a mistake by writing that, if not and you think the higher the number means the richer the mix your totally wrong.

that dude knows more about tuning that you do.


The post prior to edit was saying 13.2.