Guys I'm really sorry if i'm beating a dead horse here but I've read every E85 post I can find on this site and a dozen others and to be honest I'm more confused than I was to begin with. My buddy has a Malibu wagon that we're considering converting. The car currently runs good on 93 pump gas but we're looking to run E85 and more boost.

350SBC +.030. Decent internals.
220 runner heads.
appox 9.0/s CR
72mm Garret
BS3 EFI
55LB/hr injectors
twin Walboro 255 pumps.
4L80E
9 inch w/3.89's
Currently running appox 7lbs boost. Want to go to around 12lbs on E85.

Now for the questions.

1) Reading the Wideband what A/F should we be looking for at idle, cruising and under boost. I have heard two completely different answers to this question. The first is that we should tune for the same A/F we normally see on gas (high 14's at idle, 13's on power and low 11's under boost). Then several others have said we should be around 12A/f on power and in the 8's under boost. Who is correct?

 

Do some research on it,
http://www.e85performance.net/forums/index.php
https://www.theturboforums.com/smf/index.php?topic=47094.0

It's certainly not going to run at the same A/F ratio as gasoline.
You will likely need bigger injectors and fuel pump to get 30% +- more fuel volume.

Here's my FAST XFI E85 a/f table,
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I've run it for 3 years.

 

What WB are you running? Is it reading Lamda or what is showing on the display?

 

I'm running the O2 sensor that came with the XFI.
The target table is on A/F
It just so happens that the numbers are real close to what lambda would be if you move the decimal point.
Stoich with E85 is 9.7 and lambda would be 1.
#ad


I intended on using the lambda table from the start but the setup would not go closed loop, E85, and lambda.
I know it makes no sense.

 

So your target table is based on gasoline A/F ratios?

 

????? No it's for E85.
Read the line right above the table.

 

Quote from: john01374 on Today at 09:10:12 AM

Tune for the same you would as running gasoline. Depending on the cam I shoot for 13-14's at idle and cruise, and mid to low 11's (depending on boost) under boost

I do this as well for e85, but leave the bs3 set on gasoline so the O2 sensors lamda reading is converted to gas a/f ratio numbers that are easier understood for me.

 

Has he got the timing issue taken care of? I never got a tune to look at...

 

I keep hearing about guys using the GAS SCALE for tuning E85.
WHY ?????? that's just asking for trouble.

It is no big deal to set the WB for the fuel you're using.
Either set it for the kind of fuel you're using or read lambda.

 

why would it be trouble? All it does is convert lambda to afr using a stochiometric constant for the fuel, the lambda reading is the same. Just gotta use what u are comfortable with.

 

Yes but Lambda works for any fuel and no matter what the actual % of alcohol E85 really is. That is where it is better. Just because it says E85 does it really have 85% alcohol in it? Not usually.... so when someone does the math and tells you here is the conversion from gas, you may be off depending on what the E85 really is.

I use Lambda on anything other than Gas. It really isn't that hard and just takes a little practice. Print a chart and keep it for reference.

 

**************I'll make an assumption here and that is the OP's Wideband is based on a Stoich of 14.7 and that he cannot access lambda.**************

The lambda that comes from a AFR meter is determined by measuring the oxygen content of the exhaust stream so it doesn't care what the AFR is. There is a ratio between lambda and oxygen concentration. A meter can go farther and display AFR by multiplying Stoich with lambda. Since you are using an AFR gauge that is meant for gas, when lambda is 1.00, the AFR will display 14.7. If you were burning hydrogen and lambda was 1.00, the meter will read 14.7. If you were burning coal and lambda was 1.00, the meter will display 14.7. If you were burning E85 and lambda was 1.00, the meter will display 14.7. Does this make sense?

The only way to tune is think in terms of pump gas AFR. Idle will be around 14.0, cruise will be 15.0 and heavy load & WOT measures around 12.0.

 

He can access the Lambda meter, it is a native drop down in the menu. You can also change the AFR table to Lambda too.
By selecting the fuel type as E85 it automatically switches your AFR table to Lambda and under the AFR drop down there is left and right lambda real time readings.

 

How would the alcohol percentage matter for the conversion? It wouldn't.
If alcohol percentage is gonna change than the lambda is gonna change as well as the afr will change to match. It's all the same just different ways of looking at it. If not please explain.

And yes the original thread starter and I both run a bs3, the built in wideband is capable of switching between gas, ethanol, and methanol. I just like the larger scale of using the gasoline conversion.

 

Same here.

 

Sure it would matter,

If you are using the 25% scale change for E85 you are assuming it is 85% but what if it is not? Then the scale change you are multiplying for the AFR number you are looking for is incorrect also. Not the case with Lambda, if you are looking for a .8 lambda then it is always .8 no matter what teh fuel type is.


If you pick E85 as the fuel in the BS3 software it automatically changes the AFR table to Lambda.

 

I'm sorry but you are incorrect here. If I pour gas in my tank and tune for .8 lambda then using a gas wideband it would read 11.76 afr. Now if I pour e85 in my tank regardless of ethanol percentage, and tune for .8 lambda, my gasoline calibrated wideband will read the same 11.76 afr.
So regardless if it's 0 to 100 percent ethanol it's either going to make the same tune richer or leaner and the lambda will change as will the afr along with it since it's calculated from lambda anyways.

 

You are correct and that is not what I am saying. If you do the math based on the 25% it will be incorrect unless you actually have 85% E85.

You are right as you change the mixture it will go up and down along with Lambda but if you start with the wrong AFR target to start with then you are off regardless of what scale you are using.

If you use Lambda then it does not matter if it is 20%, 25% or 30% .8 is .8 lambda no matter what fuel is used.

 

Correct. It doesn't matter what your WB is calibrated for. My WB shows gasoline A/F for the display output. When the E85 blend by me changes I know right away as my A/F changes on the display.

Now that the OP is totally confused (LOL). If you have a gasoline calibrated WB display use the gasoline A/F to tune the engine. You can do a Google search online for a fuel calculator that will convert E85 and gasoline A/F to lamda. Each fuel has a specific lamda that it runs best at. Basically all WB's use lamda in the background and just use a multiplier to give you the A/F output on the display for a specifc fuel. Most WB's are programmed to display the gasoline A/F as that is the most common. My WB can't be programed to show lamda or the E85 sclae.