I read the stoichiometric of E85 is 9.7:1. Compare that with petrol which is 14.7:1. Which begs the question, what would be needed to make a mustang capable of running E85?

Would you need to replace the 02 sensor since ours is calibrated for the narrow band 14.7 range? What other things would the tuner have to handle? Does anyone know how E85 cars are able to use both type of fuel?

I don't want to use E85. I'm just curious about the subject.

 

Stoich AFR for E85-E100 is actually closer to 9.0:1 than 10.0:1 (the more ethanol content, the "richer" the stoich AFR).

E85 is supposed to have a higher resistance to knock, which may be beneficial for blown applications. You will need new rubber fuel components (hoses, pumps, injectors, etc...), new sensors, etc... unless the vehicle was designed to be a FFV.

You will generally get worse gas mileage because the energy content of ethanol is about 2/3 that of normal gasoline. You are burning more fuel to do the same amount of work. E85 costs were more favorable than gasoline due to the heavy government subsidization.
I hope that answers some of your questions.

 

How are E85 capable vehicles able to use either E85 or 89 octane gasoline? For example the Crown Vic is supposed to be FFV. However, you don't have to swap out your fuel components if you decide to fill up with E85 instead of gasoline. How does the Ford EEC know how to handle the difference? Can it sense E85 in the fuel line or do you have to tell it that you are using E85 so the EEC can make adjustments for stoich?

 

On the FFV cars (Flex Fuel Vehicles), the fuel system components are designed to use either E85-E100 or pump gas so you do not have to swap sensors or rubber hoses.

The FFV Crown Vic uses a different primary O2 sensor, probably designed to detect the shift in AFR and switch to E85 "mode". AFAIK the OEMs designed FFV to basically operate seamlessly. Soccer moms should not be trusted to hit a "E85" button while filling up their Flex Fuel SUV, so it is automatic.

 

With a stock GT there is not much of a point, you really can't take advantage of the 105 octane the fuel will give you. Now if we are talking about a blown mustang then this is something to consider. But you are right, E85 is 9.7 to 1. I've found it can varie a bit up and down but haven't had to retune the motorcycle to compensate for it. (excelsior-henderson SuperX)

 

up to about 2003 there was sensor in the gas tank that determined the O2 content of the fuel, then the computer compensated for it. The FFV just use the o2 sensor. The 02 sensor doesn't really know what kind of fuel you are running it just measures how much 02 is in the exhaust and adjusts the fuel mixture accordingly.

 

OK. I think I follow what you are saying. Let me try to guess the sequence of events and you can correct me where i'm wrong: So when the tank sensor detects an E85 mixture, then the EEC will switch to a pogram to increase fuel by ~ 40% (to compensate for stoich differences). And the O2 sensor doesn't see any difference, the extra fuel in the A/F mixture is already burned up?

 

The percentage of 02 in the fuel would tell the ECU what percentage of ethanol was in the fuel. The 02 exhuast sensor did the fine tuning to bring it to stoich. The o2 sensor will only "see" 02, when the mixture is rich there is no 02 in the exhuast and when the mixture is lean there is more 02 in the exhaust. No matter what fuel your running..lean is lean and rich is rich. The tables here do not line up right but Lambda is always 1 at Stoich no matter what the fuel.

Fuel AFRst FARst Equivalence Lambda
---- ----- ----- Ratio -----
=======================--====================================

Gasoline stoich 14.7 0.068 1 1
Gasoline Max power rich 12.5 0.08 1.176 0.8503
Gasoline Max power lean 13.23 0.0755 1.111 0.900

=======================--====================================

E85 stoich 9.765 0.10235 1 1
E85 Max power rich 6.975 0.1434 1.40 0.7143
E85 Max power lean 8.4687 0.118 1.153 0.8673


=======================--====================================

E100 stoich 9.0 0.111 1 1
E100 Max power rich 6.429 0.155 1.4 0.714
E100 Max power lean 7.8 0.128 1.15 0.870

 

I like when ford used to pump out FFV Taurus' and Ranger's when noone cared about it and they gave up about the same time GM made a big deal about it...I think the F150's are all now FFV. Still have yet to see an E85 pump, ever.

 

I live in the land of E85.. which is selling for $1.59 right now. (true be told you break about even with a .30 cent price break) but it beats sending my money over seas........

 

You guys are WAY off. It's amazing what is stated as fact on forums.

I recently converted my '99 Mustang GT (Vortech Supercharged) over to E85 fuel full time, and I've done my research accordingly. True FFV cars have a special sensor called the Fuel Composition sensor, or a dielectric fuel sensor. This sensor detects percentage of alcohol up to 85% (E85) and adjusts a special table in the ECU accordingly to apply proper fuel amounts and adjust timing.

For the conversion, only parts needed for the swap on my GT were Injectors (60), increased flow from the Cobra fuel pumps with a KB Boost-a pump, and a great custom SCT tune by Pro-Dyno. Ethanol is not that corrosive and all OEM parts after the 80's contain materials that withstand ethanol, albeit in smaller quantities. I still have stock fuel rails, lines, and filter.

You can read more about my conversion and others, on my new website: www.e85mustangs.com

I'm currently at 471rwhp and 424 torque "on the green" and lovin' it!

 

This is pretty awesome and something that I'd maybe be interested in, in the futere when E85 becomes more available through out the country.

 

The FFV's tend get horrible gas mileage according to fueleconomy.gov with good reason because ethanol has less energy than gasoline (roughly 2/3 the energy content of gasoline).

How long has your Stang run on E85 w/o changing the rubber hoses, lines, gas tank, etc...? I read that E85-E100 requires different materials. You are correct that most cars made after the 80s can use ethanol, but only up to 20% (E20) for short periods of time (this is what GM powertrain engineers and refinery engineers have told me). There's a section in my 07's calibration that allows you to adjust the stoich AFR for ethanol, gas, or CNG which suggests that Ford at one time wanted to make the S197 a FFV. I wonder what exactly we need to swap out to make it run OEM-reliable on E85? I have no plans to actually use E85 because it is a step backwards in alternative fuels, but I'm always interested in reading about DIY mods.