I know the safe/conservative AFR @ WOT is in the 11.xx:1 range. What should my AFR be to be safe?

 

Depends on your specific engine and modifications. Most professional tuners choose to tune AFR @ WOT to Rich Best Torque (RBT). Differing AFR's within a "window" of adequate fueling will make roughly the same power. That said, being on the richer side of the same power level will make your engine last longer as fuel cools the combustion process. Think of proper fueling as thermal management.

I target 12.2:1 during spoolup tapering to 11.1:1 at redline.

 

holly cow my car at WOT close to red line is on 10.0 is that too bad should I be worried? I will be calling the company that flashed my ECU

 

10.0 Would be very very rich. Need to lean that out some in the low 11's

 

Yah I am definately looking for engine longevity. This is my dd, I have a race car in the garage. Looking for 100K+ miles. I beat on it quite a bit, but am a stickler for premature maintenance. Does that help hone in on a better AFR I should be shooting for?

 

mine is 10.0 I have a flash from AMS

 

For email flashes, tunes have to be safe for a variety of engines so there is an extra safety factor. When you get a custom tune, the tuner is able to tune your AFR to the specific needs of your engine. Additionally, if your road racing you may want to tune extra rich to provide additional thermal management since an Evo will spend much of the time around the track in boost. Too much fuel can cause problems as well, poor gas mileage, misfiring, spark plug fouling, ring washing, dirty bumper, excessive carbon buildup, etc.

A stock Evo is tuned very rich, in the 9's I believe. Why? Mitsubishi had a 100,000 mile warranty on these engines so it's a balancing act between reliability and max power. Also they had to tune for a variety of fuels 93oct to 87oct since they can't guarantee everyone is smart enough to read.

See the sentance just above your quote. Anywhere from 10.0:1 - 12.0:1 should be in the ballpark. If you add fuel and immedatly lose power then you are too rich, if you reduce fuel and immediatly loose power then you are too lean. If your in-between power should remain close to the same, and like I said, your better off being on the rich side, hence RBT.

 

10.0 is very very conservative, it's like stock AFR. I can definitely smoke you on high end. Did they even tune your ecu? I don't know why would any tuner set the AFR at 10.

 

I dunno if I would be running around at 10.0 a/f, like Mr IX said, it leads to ring problems and horrible gas milage, the way gas is these days I would fix that. Atleast get it mid to high 10's if anything.

 

They didnt do it right the first time, time to pick a new tuner =-)

Shoot me a PM if you want it done right the first time.

Cheers!

 

11.2-11.4 would be best.... It really depends how aggresive you want the car. I've done some at 11.5-11.6 and others 11.0-11.1

i wouldnt tune it leaner than 11.8, after that youre asking for trouble.


Cheers!

 

Listen to this guy, he knows what hes doing and talking about, I dont even have one of his tunes and can tell you that. He will hook you up with a safe tune and one that will give you power gains.

 

I'd bet there is less than 5% difference from 11:1 to 12:1 if all other variables remain the same. I saw a demonstration of this on a dyno, mind you it was on a low compression NA car but there was very little power difference from 8:1 to 17:1. Basically in this test the car made the same power till it started misfiring at 20:1. The higher the cylinder pressures achived the smaller the window. So don't think a 4g63 will let you do this but you get the point.


And 4WS is correct, there is a right way to calibrate an engine and many people don't do it the right way. I've done some things wrong in the past because I didnt know any better.

 

this is true i've tuned pretty lean in my own car high 11's close to 12's but i richen it up to mid to low 11's and there is no noticable difference in power. but its safer.

 

i will give it a try as soon as I get more stuff done and get some money in my pocket I will send u a PM to know about the price and where do I have to send my ECU so 10.0 is not bad to be running right now? I don't drive the car very often but I'm right now since my beater is getting some work done too .