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E85 Question?
Posted: Mon Jul 10, 2006 5:34 pm
by 2001dodgeneonrt
I am currently tuning my setup to 11.5:1 on 94 pump gas in boost. From what I understand if I was to switch to E85 my AFR would be around the same for it correct? I know I need 25% more fuel so bigger injectors are on the way. TY in advance and sorry for the newb question just want to do things right.
Posted: Mon Jul 10, 2006 7:57 pm
by PSIG
Okay - that's a confusing statement. If you mean that the O2 sensor will report stoich at the same point - then yes. From the O2 sensor's viewpoint stoich is stoich and it will output the
same voltage reference for stoich for most fuels from LPG to diesel. The
AFR for E85 is different than gasoline and I assume that's what you meant by the 25% more fuel, however, if your MT is setup to display AFR and relates 14.7 (gasoline) as stoich the E85 stoich point will still be correct, but the relative AFR's will be displayed wrong.
Okay, I think I just made the confusion worse...
I'm tired - maybe someone else will take a stab at this...
Posted: Tue Jul 11, 2006 8:46 am
by 2001dodgeneonrt
Basically I need to know what afr to tune to with the E85? I tune to 11.5:1 now on 94, will the number be the same on E85? This kinda has me confused and just looking for some explantion. thx!
Posted: Wed Jul 12, 2006 1:34 pm
by turbo54
At this point, it would be easier to discuss mixtures in terms of lambda...
Ethanol, Gasoline, or any mix of the two, while running at stoich (for the fuel) will cause an O2 sensor to read lambda = 1
That said, if you are at 11.5:1 AFR and its good to go, that meand you are running at lambda = .78, about 22% rich. This means your E85 should also be set up 22% rich, or lambda .78. For E85 however, the AFR will be about 7.7:1
One other point of contention:
If you are running so rich for the fuel intercooling affect (which is to say that you are knock limited by lean mixtures), you will be able to run considerably leaner with the E85, and thus, pick up power and better fuel consumption.
HTH
Posted: Wed Jul 12, 2006 4:17 pm
by 2001dodgeneonrt
ok, but will the WB read the same? If It is 22% richer then will the AFR read the same as if I was running pump? (11.5:1)
Posted: Wed Jul 12, 2006 5:34 pm
by turbo54
What kind of gage do you have? If it can be switched to lambda, I'd do it. Lambda is universal amongst hydrocarbon fuels.
Otherwise, I suspect when your gage reads "11.5" it will mean the same thing your used to thinking.
Posted: Thu Jul 13, 2006 3:10 am
by 2001dodgeneonrt
ok, ty for the help...