DMM

Enjoy it while it lasts. You're too lean, it's gonna go boom.

jclayc

iTrader: (8)

I don't know a lot but I thought SC engines could/should run a lower AFR number. From Magnuson "Each supercharger was finely tuned to a near-perfect 12:1 fuel/air ratio."

TorchRedRob

iTrader: (1)

I'm no expert, but I have heard you want to be closer to 11:1 if you are still at the stock (high) static compression ratio in order to combat detonation.

Whitten

iTrader: (1)

I know with boosted cars you generally want to run a richer mixture which I figure 12.3 would be good right? Or do you want it even lower than 12.3?

Naf

iTrader: (1)

11.5-11.7 is a safe tune, 12.1 is where you make the highest numbers boosted...

Took that info off others baggerin on ls1tech.

Its really up to the end user, if they are happy with their afr then great.

I run 12.8 on my truck and 12.2 on my caddy.

Both are NA but one is 9.85 cr while the other is much higher...

Sssnake

STOCK V2s run between 11 and 11.5 on better pistons with oil squirters. It is all a matter of choice but I don't see the increased power being worth the risk on a daily driver. Besides a little margin for error is a good thing (commanded AFR is not always the same as actual AFR).


If you are going to meth then you have to account for the difference in stoich for meth. Stoich ratio for meth is around 5.5:1. MUCH different than the 14.7 for gas or 14.13 for E10.

Naf

iTrader: (1)

You know every book i read states the commanded afr should reflect the actual afr.
Which means more time dialin in the maf and injector flow, but ppl arent that patient and take shortcuts...

Sssnake

The key word there is SHOULD. Go back and re-read those books and I am fairly certain they will tell you there is quite a bit of variability within the system that needs to be accounted for (at least all of mine do). Better yet, log a few cars at different times during the year (different temps, humidities, altitudes) and prove to me that they match with less than 1% variance. You can take all of the time in the world and you won't reach that goal. The VE tables and VVE equations are models of the expected airflow. ALL models contain inaccuracies and/or limitations in fidelity (as I have spent 20+ yrs modeling some of the most sophisticated systems in the world, I do consider myself an expert in the field of M&S). The MAF signal is fairly noisy itself and therefore cannot be trusted to produce 1% accuracy outside a very steady state conditions. Then there is the fuel system. How common is it for fuel pressure to drop at high demand. Pretty damn common. Our ECMs don't even measure fuel pressure. How about fuel temp. Several ECMs track it. Our ECMs don't. Do you test your gasoline every fill up. I bet not. What happens when you hit a bad tank of gas? SO if you feel comfortable being on the edge of detonation then have at it. But blindly suggesting it is VERY safe for others to do the same is asinine.

Now you will likely come back with some post harping on the arbitrary 1% value that I picked. As stated, it is arbitrary. How close does AFR need to be? It depends upon what your target is. This brings it all back to my point, go with a more tolerant setting and enjoy miles and miles of great performance. Go with a less tolerant setting and have a small error in the tune or with the engine and have fun rebuilding your engine.

Naf

iTrader: (1)

I said i got it off ls1tech where ppl are baggerin...

Try searchin the corvette forum...you will find what i am talkin about.

DMM

Charles is the man when it comes to this. He's spent a lot of time on fueling and is pretty much the go to guy for fuel systems for our cars.

For an LS6 to be at 12.3 AFR at the top of its rev range on boost tells me there was probably no MAF tuning done, as the OE tune leans out at 6k RPM. This is what I normally see when the PE is manipulated in an attempt to get a desired AFR.

OP's car may run like this forever. Or, if he does a long 4th gear pull it might pop, which would be my concern.

I'd stick to second gear pulls for the time being, OP.

Ls1drew

So should I be concerned with the 12.3? Where should it be?

Naf

iTrader: (1)

Your tune is a little lean basically anything over 3500 RPM you should be below 12.0 around 11.5 to 11.7

Ls1drew

Ls1drew

Seems to just get above 12 up top.

Ls1drew

Question.... I have 60# fuel injectors and the Kenny bell adjustable boost a pump right now, could I go e85 with this?

Naf

iTrader: (1)

No, you have to change the pump, and injectors to properly run e85.

1BADCTS

iTrader: (17)

So the meth would bring him right in line.

Naf

iTrader: (1)

He needs to correct it, but yes it will help when it is workin. When the fluid runs out he will be right back at square one

Ls1drew

Tuner agreed above 12 is too lean. He's gunna look at it Thursday. Thank you all for the feedback and information.

Ls1drew

Tuner has the car showing low 11s all the way to redline. Feels like this may have cost me a couple hp, no big deal if it means a longer life for my motor. Turned the fans to come on at 185°. And got it running smoother down low buy putting a nitrous pill in the tube coming from the throttle body.

One thing I've noticed on occasion, with traction and stability off (press and hold for 5 sec), in first gear, under full acceleration (usually lots of tire spinning with this), the power will cut out like traction control is on. And then come right back. Maybe 1 out of 10 times. And it's been up around 5k or 6k rpm. Is this a tune issue? Belt slip? Idk what's going on... any ideas? This was noticed before the tuning adjustments were recently made.