Location: Brooklyn New York The DVL and the chicken sleep with the fishes....
A/F Ratio Question
What should to optimal A/F ratio be on an otherwise stock ls2 with a procharger or similar system ? More importantly , what is the point that is so lean that it can cause damage ? Thanks Folks !
What should to optimal A/F ratio be on an otherwise stock ls2 with a procharger or similar system ? More importantly , what is the point that is so lean that it can cause damage ? Thanks Folks !
Engines are all a little different so optimum AFR will vary slightly as far as producing max HP.
GM puts a very conservative tune to fuel you engine to make up for all the differences in the LS2's.
That is why people are getting some free HP just tweaking a stock computer.
As far as AFR on a stock engine with add on forced induction shoot for 12.5 - 12.8 at WOT .
I have an EGT in my car on the leanest running cyl on LS engines, #7 .Then I tune my car for optimum temp on that cyl.
If you are running high boost levels you can go as rich as 11.0 or more to achieve max power. Running a little richer also reduces detonation by it's cooling effect.
As far as leaning it out where it can cause damage. At WOT your AFR is critical, so running leaner than your optimum tune for power is going to create extra heat and detonation in your engine. You have cast pistons and they would not fare well.
That being said , It depends how long you stand on the throttle when the lean condition arises.
If you have a fuel problem at WOT you need to take care of it before it takes care of your motor. Much more critical with forced induction..
C6Dude,
I think you meant to say 11.5 to 11.8 for a blown situation, 12.5 to 12.8 is way too lean for a force inducted engine, general rule of thumb for tuning is 12.8 to 13.0 for a naturally aspirated engine, and 11.8 to 12.0, with a little more fuel at peak torque for a forced inducted engine (supercharger or turbo), some engines are different and want more fuel. Every engine is different and will tell you what they want on the dyno when tuning, just make sure you keep your timing reasonable when tuning for blown applications, so you don't get into any detonation. Good Luck, Geoff.
C6Dude,
I think you meant to say 11.5 to 11.8 for a blown situation, 12.5 to 12.8 is way too lean for a force inducted engine, general rule of thumb for tuning is 12.8 to 13.0 for a naturally aspirated engine, and 11.8 to 12.0, with a little more fuel at peak torque for a forced inducted engine (supercharger or turbo), some engines are different and want more fuel.
C6Dude,
I think you meant to say 11.5 to 11.8 for a blown situation, 12.5 to 12.8 is way too lean for a force inducted engine, general rule of thumb for tuning is 12.8 to 13.0 for a naturally aspirated engine, and 11.8 to 12.0, with a little more fuel at peak torque for a forced inducted engine (supercharger or turbo), some engines are different and want more fuel. Every engine is different and will tell you what they want on the dyno when tuning, just make sure you keep your timing reasonable when tuning for blown applications, so you don't get into any detonation. Good Luck, Geoff.
Geoff
12.5 -12.8 is what I meant.
The reason is because he said on a stock LS2 with a bolt on kit.
I agree with richer AFR for higher boost levels.
There is a tuner on this forum who goes even leaner, 13 or more at WOT with no detonation. He has tuned cars for many years and is a veteran tuner. I was at his house a couple of months ago and he gave me some pointers and showed me some of his results. I was floored when he told me that and I was real sceptical. I will not reveal his name because he is secretive with his tuning like most tuners.
Some tuners I know in my area will run very rich AFR's to cool the cylinders if they are experiencing detonation because they do not want to lower their timing any more. I think that is a bandaid approach.
Myself ,I put a base timing map for F/A apps. Then I set the AFR where it makes the most power on the dyno. After that I start playing with the timing tables again raising timing slowly until slight detonation is present ,then I back it off until it's completely gone.
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12.5 -12.8 is what I meant.
The reason is because he said on a stock LS2 with a bolt on kit.
I've got a stock LS2 with a bolt on kit and you woudn't catch me dead running anything over low 12's on a FI car.....and I run Torco and straight meth, so detnoation is no problem for me. My current A/F up top is 11.7-11.8. To each their own though.....opinions on FI cars, safe boost levels, A/F ratios, is like watching the local weather forecast, every channel has a different % chance of rain.
Location: Brooklyn New York The DVL and the chicken sleep with the fishes....
On my last Dyno run the car was pretty much stable at 10.2 to 10.6 through the rev band - Of course I had told my tuner that I wanted a very conservative tune - but is this running TOO rich ? Based on your explanations it seems I have a good amount of horsepower to gain while still staying in "safe" territory ? Thanks Guys
On my last Dyno run the car was pretty much stable at 10.2 to 10.6 through the rev band - Of course I had told my tuner that I wanted a very conservative tune - but is this running TOO rich ? Based on your explanations it seems I have a good amount of horsepower to gain while still staying in "safe" territory ? Thanks Guys
Damn, that's REAL rich.....and unnecessary if you ask me. You should really be in th levels discussed above.....conservative would be 11.0-11.5, IMO. But, I'm no expert and no tuner.......some actual "tuners" may chime in here
Damn, that's REAL rich.....and unnecessary if you ask me. You should really be in th levels discussed above.....conservative would be 11.0-11.5, IMO. But, I'm no expert and no tuner.......some actual "tuners" may chime in here
Way too rich....
You have some power left on the table thats for damn sure.
...... For a conservative safe tune for people that are street cruisers and daily drivers ,I set AFR to 12.0 at WOT. When I adjust their timing for power I back off a little more than usual after sensing KR to give them a bigger window for safety.
Aside from loosing potential power and maybe burning more fuel - are there any reliability downsides to running such a rich tune ?
.....A little rich is OK ,but yours is too rich
After a while you will form deposits on your pistons and combustion chambers in your heads. Then you risk detonation because the deposits glow red hot and ignite your mixture before the spark plug does. (very bad).
Location: Brooklyn New York The DVL and the chicken sleep with the fishes....
Quote:
Originally Posted by C6dude
.....A little rich is OK ,but yours is too rich
After a while you will form deposits on your pistons and combustion chambers in your heads. Then you risk detonation because the deposits glow red hot and ignite your mixture before the spark plug does. (very bad).
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Gotcha - That makes alot of sense I guess this is something I have to take care of - Thanks for the Info !!
.....A little rich is OK ,but yours is too rich
After a while you will form deposits on your pistons and combustion chambers in your heads. Then you risk detonation because the deposits glow red hot and ignite your mixture before the spark plug does. (very bad).
On my last Dyno run the car was pretty much stable at 10.2 to 10.6 through the rev band - Of course I had told my tuner that I wanted a very conservative tune - but is this running TOO rich ? Based on your explanations it seems I have a good amount of horsepower to gain while still staying in "safe" territory ? Thanks Guys
How do you know what your air fuel is do you have a guage in the car.
When i get my clutch fixed i would like to put An LM1 wide band in my car.
Location: Brooklyn New York The DVL and the chicken sleep with the fishes....
Quote:
Originally Posted by LS7 ZO6
How do you know what your air fuel is do you have a guage in the car.
When i get my clutch fixed i would like to put An LM1 wide band in my car.
I dont have a guage , but I am thinking about getting one now.... right now all I have is a boost and FP guage . When my tuner runs it on the dyno , they moniter A/F ratio on their comp.
i just put a aem wide band in my car ($275.00). works great. it also works well with my hp tuners software. they already have it in their menus. it nice to know when you got this much damage potential that things are ok!!!!
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A/F Ratio Question
