Thread: Why I tune to 12.0:1 A/F ratio (0.82 lambda) and why you should too. (all welcome)

Stratton, I would say you're pushing that T28 a bit too hard with the 16 psi and S4s. You might try less boost on the dyno, you might gain power. Worth a shot.
Also, Coheed's advice is good. Use it.

I've driven a DET as rich as yours. It was an absolute mess drivability wise. Fixed the fuel and it ripped.

As for extra power, I think you might make a little bit more, but that T28 is getting to its limit. I think you could make the same power with maybe 13 psi and better fueling. Try a few things on the dyno. Keep that top mount cool.

no top mount. its a fmic.

but maybe i am pushing it to hard.

as far as driveability goes its great only time you really notice how bad the a/f is after say 6500 were power starts dropping off so if i shift at about 6500 and dont wind it out to 7800 in 3rd and fourth or even fifth lol its good.

but thank you very much for the advice.

i will recommend to my tuner that he gets the a/f right and then start dropping the psi a bit.

stratton.

Might want to edit your previous post then.


You're really limited without being able to tune timing. Normally, once you get the fuel sorted then you can mess with timing and try to actually make power. You're missin' out man! =]

Actually have you tested on a Dyno how much whp do you get from leaning a car from lets say 11.00 to 12.00 at a same amount of boost and same timing i dont know I will just guess 5-10whp I dont think its worth it to risk how much the engine will last for 5-10 whp on a street driven car...

Okay, there seems to be a lot of talk about 12.0:1 not being too safe, and richer being safer. I'd like to reiterate that while practically, that notion is true, you need to realize what you're giving up for that combustion safety (I think it's obvious by now I don't think you need that large of a margin of safety, but I digress).

By running too rich you are increasing the speed with which your (already cold and prone to fouling) spark plugs will foul.
Your O2 sensor is also suffering the same fate.
Your catalytic converter (if you have one) will surely be ruined in a matter of weeks, likely melted into a solid mass on the inside.
Your fueling system is being taxed unnecessarily. You could have saved money and kept the other benefits of running smaller injectors.
The oil around your cylinder walls is being washed away each intake and exhaust cycle causing premature wear of the cylinder walls/piston rings and extra heat. The oil is also added to the combustion mixture increasing oil consumption, spark plug and O2 fouling.
You consume more fuel than you have to.


If you want to make abso-freakin-lutely-sure you don't detonate, and are willing to accept the consequences, then by all means, go ahead.

I'll take the extra 5-10 WHP, fuel savings, less wear and tear, less fouling of parts, and still avoid any hint of detonation thank you very much.

Dude i dont get your point^^^^ you dont tune your car to run ALL THE TIME on 12.00 AFR only on WOT you run that rich...When i tune my car it idle at 14.0-14.5 and It runs like that cruising too and it richens up when you get on partial load up to 13.5 and WOT it goes progressive to 11.2... So all the parts you mentioned that will be damaged from over fueling wont be damaged at all .... Because you don run WOT all the time unless you have a rececar.... And I get 20mpg+ on a 484whp street driven car on pump gas plus meth without braking any parts...

Since you brought up idle and partial throttle conditions I'll address that again (second time in this thread).

Personally I tune idle to as lean as I can while avoiding lean misfires. For my engine that means anywhere from 14.8:1 to 15.7:1 (it tends to wander).

Cruising I tend to aim for 15.4:1 exactly and do a good job of that.

Partial throttle acceleration can be anywhere from 14.7:1 to 13.8:1 depending on how "partial". =]


I see you like to tune much richer than I do everywhere Payu. I can't say I'm surprised. Care to explain your reason(s)?

I can't think of a single advantage of running richer during cruise, idle, etc.
It's not like we need to avoid overheating.

You'd be surprised at how often I'm at WOT, and others I know. I know people with cars as powerful as yours who are either full throttle or on the brakes during their daily driving. Don't ask me why, they just are. Sure, that's a bad example, but you'd be surprised at how fast you ruin things running rich at WOT. Running lean at cruise and idle can certainly help avoid fouling up the plugs and O2 sensor but I'd argue you're not running lean enough to do that, and even if you were, it only helps so much.

I tune that way because I don't like the hesitation of lean misfires with cams and I don't like the V8 Idle that cams produce and also I like the throttle response those AFR's provide also WE live in the tropic and it tends to get very hot and humid during the day and when you get into the everyday traffic it gets worse.....

Good thread...

From my experience..

I like to run crusing at 15,5 16 a/f all the time this give better gas miles keep the copper plugs clean etc. on partial throttle 13,5-8 then its gets rich at 85% of throttle at 12,5-1 and depens on what fuel Im using 12 to 13( yea 13 at wot never had a single prob doing this
you get better flame distribution better burn flame and clean flame doing this... that means knock resistant ( all of this on meth) .
on pure pump fuel its depends on the boost but 11,5 to 12 its ideal.
I always tune with a EGT from 11,1 to 12 there are just a cuple of hp but the burn rate changes dramaticly the responce is totally diferent You got better recover from gear change etc...well the egt at 11,1 start slowing up to a 760celcious at 12 .1 I got 770 on pump .. if you ad meth (depends on the cuantity) the temp drop incredible up to 650c so On meth I lilke to run at 12,5 , on race gas plus meth o water 12 high same egt.. less than 700c in 4 gear to 7700 rpm, you people need to control knock with timing more than fuel. My setup is focus on top speed racing, for road racing I would tune a little diferent .
Cheers.

good point.
In every wheather the tune has to be diferent humity mens more knock so you need to be more conservative.