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View Full Version : Wideband A/F ratio ballpark



overlordsshadow
01-05-2008, 01:04 PM
Hey guys,

Putting in the Lc-1 right now. Want to do some slight tuning later (only variables are cam and ignition timing). Have the stage 5 comp but mostly stock parts on there until the head is done. What is a safe fuel ratio? How will I be able to tell if it is detonating or not?

91 octane, mitsu turbo, intercooled, adjustable cam gear, stock ignition, open exhuast

BadAssPerformance
01-05-2008, 01:12 PM
For power? On a turbo car, shoot for ~11.5:1... at WOT at the top of 4th gear.

For gas mileage? Ask someone else! :D

overlordsshadow
01-05-2008, 01:18 PM
Alright, this damn LC-1 doesn't come with instructions for the digital gauge....


What is an unsafe fuel ration. I don't have anything to adjust the fuel with right now so I want to know once this is set up whether to switch back to stock.

BadAssPerformance
01-05-2008, 01:24 PM
If you cant adjust fuel, just start out at low boost. Run it off the manifold to start so it is less than 10psi. Make a couple passes, monitor your A/F. slowly raise the boost, like 1 or 2 psi at most at a time, make a couple passed with each step. I'd use 12.5:1 as the absolute lean limit for safety... but I tend to be a little conservative.

Frank
01-05-2008, 01:32 PM
If you cant adjust fuel, just start out at low boost. Run it off the manifold to start so it is less than 10psi. Make a couple passes, monitor your A/F. slowly raise the boost, like 1 or 2 psi at most at a time, make a couple passed with each step. I'd use 12.5:1 as the absolute lean limit for safety... but I tend to be a little conservative.

Yep! The only time you want to be higher then 12.5 is when you are cruise and not in boost.

overlordsshadow
01-05-2008, 02:02 PM
How far down from the swingvalve should I mount this thing?

Frank
01-05-2008, 02:10 PM
2-3 feet for reliability and to ensure accurate readings.

overlordsshadow
01-05-2008, 02:21 PM
looks a bit hard to get that sensor in there at that 10-2 angle on a shadow. I was thinking around 16-18 inches from start of DP.

Frank
01-05-2008, 02:30 PM
Well then just go for as far away as you can.

GLHNSLHT2
01-05-2008, 03:00 PM
min is mounted at the 1st slight bend in the d'pipe. Works great. http://www.pnw-sdac.org/gallery/main.php?g2_itemId=2537

This allows me to get the controller to mount on the tranny mount bracket on the driver's side. The O2 sensor lead is too short. Also clears all the shifter BS. And it's a position where water won't collect on it.

Check Innovates website for instructions on wiring up the gauge. They have a great PDF section that has all their instructions.

Did you get the DB gauge or the XD16?

Anthonytad1985
01-05-2008, 09:10 PM
Try not to install in a bend, the bend itself is a restriction then putting a sensor in is even worse. Just my .02

overlordsshadow
01-05-2008, 09:23 PM
What is lean and what is rich? I see all these numbers but I don't know which is which.

Anthonytad1985
01-05-2008, 09:49 PM
10-10.5 is real rich for WOT and anything higher than 12.5 is too lean at WOT. City driving you will be around 14.7 14.5-15.

t3rse
01-06-2008, 11:38 AM
you want to aim for 11.7-12.0. if you get any knock go to 11.5. don't go any richer...

not all widebands are created equal, so still check your plugs.

METZ
01-07-2008, 07:47 PM
For power? On a turbo car, shoot for ~11.5:1... at WOT at the top of 4th gear.

For gas mileage? Ask someone else! :D

I wonder how close the factory came to the optimum A/F ratio at WOT. Has anyone ever checked on a stock setup?

1FastCSX289
01-07-2008, 08:46 PM
What is lean and what is rich? I see all these numbers but I don't know which is which.

Technically, 14.7 is the stoichiometric (perfect) ratio......which is what you want while cruising and anything numerically lower is rich.....higher is lean. Like the others have said, aim for high 11's to low 12's depending on how much boost youre running. The higher the boost, the richer you want to run it to be safe. My ratios are all set in the 11.5 range for safety. The extra few HP you get from moving more towards 12 isnt worth it IMOP.

shadow88
01-07-2008, 10:54 PM
Just to add to 1fastcsx289, when I was setting my car up on a dyno in '06, I lost only 5 whp and 4 wtq while changing the a/f ratio almost 1 point richer.

METZ : I did it once. my car ran richer than 10.0:1 all the way to redline with 12 psi boost. 10:1 is as rich as my display reads.

GLHNSLHT2
01-08-2008, 01:41 AM
my buddies T1 85 yorker pegged the wideband on the dyno and it was mostly stock.

mario03SRT
01-08-2008, 11:14 AM
I'm going to go out on a limb and say the stock 2.2/2.5 engines come from the factory in the upper to mid 9's afr wise. All of the stock and staged srt ecus run very fat and on the AEM WB for instances were too rich to even read out.

johnl
01-08-2008, 02:11 PM
I'm going to go out on a limb and say the stock 2.2/2.5 engines come from the factory in the upper to mid 9's afr wise. All of the stock and staged srt ecus run very fat and on the AEM WB for instances were too rich to even read out.

Sounds like the safe thing to do, if you are a manufacturer (already meeting CAFE standards) looking to avoid warranty claims and anticipating "make it faster" owner/aftermarket modifications.

johnl
01-08-2008, 02:20 PM
What is lean and what is rich? I see all these numbers but I don't know which is which.

So you can remember which way to go, which is which -

After all, it is called - "Air vs Fuel" ratio. That is, the more air, the less fuel. So, we are talking about the first half - air - so a "12" means more air. A "12" is leaner than a "10."

People getted twisted around on this because a "10" (a lesser number) means more fuel. So, when your standing there, figuring which way to go on fuel, think "It is Air vs Fuel" and you'll get it right.

mario03SRT
01-08-2008, 03:41 PM
Sounds like the safe thing to do, if you are a manufacturer (already meeting CAFE standards) looking to avoid warranty claims and anticipating "make it faster" owner/aftermarket modifications.

Zaggly!