Considering an E85 Experiment
 

I've recently done a little more reading on E85, and I'm contemplating an experiment. I only have a few stations in my (greater) area, but it happens that one is near my regular route (it adds about 4 miles to the total trip).

Anyway, my car (even tuned) runs on the rich side (~11-12:1 AFR), but I was reading that stoich for E85 is actually 9:1. Now I know that I might be seeing a decrease in power, but would this essentially be forcing my car to run in a lean-burn mode?

I'm also thinking that, given the bad gas we have in CA, I would only see benefits from the higher octane rating. The idea that E85 is ~ $0.50/gallon cheaper and I only have to fill up once a week (i.e., I'm only going 4 extra miles out of my way every ~ 350 miles) is also appealing.

Regardless, I'm thinking that I might want to test this out... if nothing else, just to see the results. I've fallen into a pretty good routine, and though I wouldn't be able to give an accurate A-B-A testing, I could probably come up with a good estimate of how e85 affects my FE.

I'm due for a fill up tomorrow night, so unless I hear "Danger Will Robinson," I think I'll give it a try.

You could go whole hog, or ease into it with blends.

i did drive some ethanol in my mx5 (miata). the car is verry rich running in open loop. with plenty of ethanol it was at lean verry often. cold start, cold run (was noticeable affected, some kind of bad throttle respond), WOT, and high revs. as long as the o² sensor was aktive, everything was normal. with the higest level of ethanol i tryed, the open loop was lean burn always, with one exception: verry high revs, 5500 rpm and more. in this area the setting is so rich, the ethanol doesn´t catch up.

in the mx5 i can adjust the FAR with the airflow sensor. i decided to klick it to the lean side so far, that the open loop will stay in the middle of the scale, maybe a little lean. then the verry high rev setting will be rich of course. for safety on trackdays.

fiddeling with ethanol is to complicated for me, i will make a one for all setup. if i hadn´t the adjustment to make, i would search for the best percentage of ethanol.

btw, AFR is monitored by a ARF gauge and the stock o² sensor.

I would ease into it, make a E25-30 something blend first tank, go to E35-40 next tank.

You might find a sweet spot where it actually gets better MPG with a blend.

Hmm... I might want to wait a week, then. That way, I know I'll have ~ 4-5 gallons of gas, and I can top it off with 8-9 gallons of E85.

Check out the Stratus fuel log, that's what I've been doing. Just never that heavy on the E85, don't know when the E85/E70 switch over is so it might be E70 your buying.

FWIW, before I modified my 4.3 s10, as long as I had 1/4 tank of e10 I could top off with e85 and stay within the stock ECU's +25 fuel trim bandwidth.

On my 4.7HO jeep, fills-up from empty on E85 keep me inside +20 fuel trim on the stock ECU (trim runs at -1 to +1 when I fill from empty with E10) - but the HO engine has higher flow rate injectors.

It should be noted that the stoichiometry difference between ethanol and petrol has the natural benefit of reducing pumping losses - specifically since the fuel delivers some of the oxygen necessary for combustion, less air needs to be drawn through the engine for a given level of output. So as has been noted elsewhere, between the timing benefits of a higher octane fuel and the reduced pumping losses of a more oxygenated fuel, there have been reports of improved MPG on blends despite the lower BTU count per unit of volume.

What did you do to convert the 4.3 to FFV, zr2 truck for sale near by w/5 speed is tempting me & what's it mpg with E85?
I need to figure out how to get those fuel trim setting out a SG2.

Not much really, at first I put a Flex Fuel "kit" on it... what this device does is adjust the length of injector pulses by + or - 15% and lets your o2 delta do the rest. Brilliantly simple and it operated beautifully on that for ~40k miles. I then started looking for more power & kinda felt like tinkering so I had the stock ECU reprogrammed by wait4me with a map I specified after studying the software they use (and a few other tweaks) and at the same time replaced the old fashioned poppet type injector setup with the 2004+ style new injectors - and due to the new ECU program I installed a higher flow aux. fuel pump inline to maintain pressure at WOT - all of which negated my need for the FuelFlex kit that had been previously installed. I have another ~30k miles on those modifications with no difficulty, and simply love the way it runs on ethanol blends.

Note that I had zero trouble with the "kit" and if I hadn't wanted to do more tinkering, I would still be using that kit today and have no doubt it would continue being trouble-free. I already sold the kit I removed to a friend, but if you buy that ZR2 & are interested I have a second GM 4.3 fullflex kit that's never been installed, would be happy to sell it for a mutually agreeable price. :thumbup:

As for MPG's, it should be noted that my aerodynamic profile is a little different due to the 5" of suspension lift and the live front axle hanging below the frame ( from the factory these vehicles have independent suspension in front and a smoother underbody profile) and I also undertake literally zero effort whatsoever to "hypermile" my drivign habits - on ordinary E10 pump gas I usually get about 275-320 miles before topping with 17 gallons, and though I don't frequently get to run back-to-back fills of e85 (to ensure it's really e85 not some blend in the tank).. scangauge and partial refills have indicated that I average around 16-17mpg on straight E85, and closer to 18mpg on blends I estimate live around e50

@ shovel: I'm hoping for some similar results. The timing is very far advanced, and the stock fuel system feeds enough to run super rich on gasoline (E10?). I think that right now, for experimentation purposes, I will also try to shoot for the ~ E50 mark.

It doesn't really matter to me whether they are currently providing E85 or E70... The ethanol count will still be increased far higher than my current fuel. I'm not quite ready to jump fully onto the 100% E85 (I'm looking for ~ 2:1 mix with gas), but even if I were, I should be fine. Given the current tune for my car (and my estimates for stoich AFR), even pure E85 should be 1.1 to 1.2 lambda during cruise and dropping to <1 lambda under boost.

Ahhh, you have boost! Your engine should love this stuff!

That's the plan! :D

for mileage, ethanol likes about the same air fuel ratio as gasoline.

for HORSEPOWER, you can run as much as 7 or 8 to one. The extra fuel supercools the air charge much like Nitrous does, allowing more air into the cylinder, making more power.

@ drmiller100: Not to be a bother, but can you cite any sources for that? Everything I've read puts E85's stoich at just under 10:1. I understand running 7-8:1 for power, as that is the same concept as running rich with gasoline (usually 10-11:1) for power. But in terms of stoich, I thought that complete burn off is complete burn off. So rather than the 14.7:1 for gas, E85 has ~9.7:1. I know that you can obtain better economy by going beyond stoich, but everything I've read (this is in terms of gasoline) states that leaning out any further than 1.2 lambda doesn't do a whole lot.

Going further than 1.2 equivalence I'm guessing is to cut pumping loss by a little, but after 1.2 the flame temperature drops past what it would be at stoich or something so the gains are smaller.

Just put on 272 miles with E66:
1.0g E10 = .1g E + .9g regular
15.0g E70 = 10.5gE + 4.5g regular;
=10.6g E + 5.4g regular; 16.0g total;
=E66

I know I started with an empty tank because I literally ran out of gas on the way to the station. I only put 1g reg in because I didn't like their prices, then 15g E"85" @ $2.90/g, saving over $11 vs filling up the day before. :thumbup:

I presume it was actually E70 due to the time of year, but at 70+ degrees out it seems summer has arrived.

No issues, not even a CEL flicker. At end of 272 miles, gauge is sitting just over 1/2; call that 8g burned = 34mpg. Winds were light and variable, not necessarily favorable, cruised between 53-58mph.

34 mpg would be a good number for this car on regular. Perhaps the accessory drive mods helped a bit...? Perhaps E85 isn't the road to ruin?

first, ethanol is lighter then gasoline, and injectors inject via volume, and stoich is normally measured by mass.

so if you squirt pure ethanol vs gasoline with an injector, you will find mileage is off about 20 percent, or, another way to put it, you need to squirt about 20 percent more ethanol then gasoline to make an engine run happy.

if it were truly 10:1 vs 14:1, your numbers would be 40 percent different.

my numbers are based upon personal experience with about 50 cars and LOTS of other people who have really tried it.

I'm not entirely sure I'm understanding you here, but maybe because percents are funny things..

14 is 140% of 10, but 10 is 71.43% of 14 (or about 28-29% different)

:thumbup:

Ok. I was under the opposite impression. As I was understanding it, ethanol is denser than gasoline, but it contains about 30% less energy per volume. But, since you need ~40% more ethanol per volume of air (to maintain stoich), the ethanol would produce slightly higher amounts of power per a given amount of air intake.

I don't have any personal experience (obviously), but I am basing this on what I've read. One of the most complete sources I've come across at this point is here: Converting to E85 (ethanol fuel) - Turbobricks Forums

I'm still considering making this jump, but I have cause to be leery right now. According to everything I've read, the ECU will try to maintain its lambda settings, regardless of which fuel is used; however, because my car is turbocharged (and especially because it is performance tuned), the current fuel delivery system wouldn't be able to supply enough E85 at high levels of boost to keep up with the incoming air. I don't typically drive in that range, but I'd rather not go critically lean at > 200% load and > 20 psi of boost.

I might need to make some adjustments first, and I'm considering making a dedicated tune specifically for running E85. I'm going to ask some tuners with specific knowledge and experience on the subject before I start to move forward with this.

The O2 sensor operates on Lamba so you use the same AFR values as Gasoline. The true AFR values are different but the O2 is just feeding converted values for Gasoline.

That's interesting about the conversion. I'm looking to do that once I get up and running.:turtle:

Yeah. My main concern is that my fuel delivery system won't be able to keep up enough flow of E85 to maintain the lambda settings. I'm thinking, though, that as long as I drive normal for street (nothing more than 200% load... which doesn't happen often for me anyway), I should be fine.

Of course, I'm also wanting to adjust my current tune to maximize the usefulness of E85. I have an expert in the field (my car + E85 + tuning) whom I will want to consult, but I might also see if some people here would mind helping me see if I can mimic an Atkinson-cycle for my engine at cruise loads. :o

If you're looking at Atkinson cycle, that's a whole different topic. And we do have a discussion about that. I haven't checked on it lately though.

I still can't believe you're considering experimenting on a new car. :p If you're going to do it, get it tuned by an E85 guru. Don't risk your engine.

Ethanol is infact heavier than Gasoline. Being 33% oxygen makes it heavier and reduces it's energy density. It's also what makes it so energy efficient. :thumbup:

Risk is slim to none if one eases into it with increasingly stronger blends, noting any effects along the way.

If he keeps it in closed loop. The base map for Open loop is based on absolute values though.

Doesn't change a thing I said.

Just start mixing already and log the results. Once down 100 miles top off with E85, first tank will be e20ish. Come next refill put in 8 gallons E0/10 top off with E85, calculate the E% and just keep on going. To really test if your fuel pump & injectors can keep up you'll need to do a run or 2 after it's adjusted the fuel ratio and can supply enough fuel. I'm guessing good to E50 after than might get a CEL.

I've started trying stronger blends in my 96 4.3L S10 now too. I easing into it very slowly. Just filled up with E14 I'll let you know how it goes.

I use to run E85 in my 1994 Ford Aspire.
As long as the price difference was 62 cents or greater it was worth it.
I dropped 6-8mpg running with it.

Well one day in with a scan tool.

My live data shows VS 87 octane "winter tune"

Closed Loop
Coolent temp 165* F
IAT 79* F
Timing adv. ranges from -42.5 noload to +10 WOT
Short Term Fuel Trim -5 to Long Term Fuel Trim +16


It will be some time before I get cal. a difference in mileage

If I understand what you are saying, Ethanol is more weight dense than gasoline but less energy dense? How does oxygen make it "so energy efficient" and compared to what?

Since oxygen is floating all around, it seems lugging it about in a fuel tank is a waste of space and weight.

It cools the charge, increasing knock resistance, increases max torque, and improves thermodynamic efficiency in several ways. Despite the energy per unit oxygen burned is about the same, people who run E85 see increases in power, and it's also why some vehicles get the same fuel economy (in gallons of fuel consumed) on E85 despite E85 having less fuel energy per unit volume.

Yup, counter-intuitive isn't it? Oxygen is what makes the alcohols more energy efficient though. Granted there are engines that get MPG based on energy content, I've seen studies to verify this but then there are cars that people are getting much less to almost no loss that haven't been tested or aren't even FFVs!

Another thing to remember is that while E10 has 97% of the energy content of "pure"(I use that to mean no Ethanol) Gasoline. E85 has 71%, E70 has 76% of the energy content. By my calculations. The difference between E10 and E70 is 22% less energy. That doesn't explain the 15%-5% loss some people are getting but people forget the blends change or don't have a test kit. It's not as impressive if people are seeing a 15% loss on E70. But it's still an improvement :/

Well my tank of E14 is now gone and I have the results. No drop in mileage!

22.3 MPG on E10 with my normal routine
22.3 MPG on E14 with a few long hard WOT runs for testing purposes

Also no check engine light, hards starts, rough driving or any other side-effects so now I've filled up with E21 and will give that blend a try.

I'm loving this! This mileage is ALL CITY.

22.3 with E10
22.3 with E14
22.6 with E21 A new best for me!


Still no check engine light or other side-effects.
So now I just filled up with E26.

WOW with E26 my mileage JUMPED UP to 23.8 this is with me driving 5 MPH FASTER as well as some WOT runs.

I'm happy with this Ethanol incresse for my truck. I'm NEVER going back down to E10 again. It's now just time to get the mix "just right".

Interesting,keeping the same MPG is fascinating enough please continue to record your findings.:D

How are getting those numbers?

Using a scangage in my car it needs recalibrated every blend so it's numbers are no good, had to go tank to tank.

What do you recalibrate?

Ethanol is a weak choice as a fuel for internal combustion engines..
it does a good job fueling drunk people at bars tho??

Expensive to create competitively in Neat form..
essentially it becomes like a mime when mixed with Gasoline up to 10%
E10 has many combustion characteristics very similar to Neat Gasoline,
Vapor form Characteristics tend to be slightly different tho..

Stronger blends will pull more alcohol Characteristics.
which can be both a good & bad thing!
its a weak alcohol to use because you end up blending in a large% of alcohol to get small gains in alcohol characteristics you'd like in a *fuel*
unfortunately that same Larger % of ethanol will attack the fuel storage/delivery system even quicker than E10 does..

for the guy with the Turbo Evo wanting to run E85
you should worry more about your fuel lines turning to mush and clogging your fuel filter,
opposed to whether you have enough injector or if yer ignition timing is too advanced..
in general ethanol turns rubber fuel lines soft & sludgy..
Methanol will dry out & crack the rubber(like aromatic components of gasoline)
The alcohol guyz usually switch out to PTFE type lines (teflon/steelbraided is the usual choice)
u can also use Flourine enhanced rubber lines but they are SUPER expensive like $20/foot
and don't like Cold tempatures..
also oil changes are needed Much more frequently with E85
(alcohol use tends to turn the oil watery instead of dirty and dark)

i personally think you may be able to get away with slightly stronger blends with Ethanol
i'm assuming your engine was tuned on E10 close to MBT w/some cushion
Using a slightly higher% blend, MBT ignition timing may no longer be knock limited as it was on E10.. mostly due to the blended fuel's New chemical composition of more "alcohol"

but since you're Living in L.A.
you should analyze what your Goals are?
whether its MPG's, 20Psi boost / Power, or regulated Emissions
if you're just wanting to play Dr.Jekyll / Mr.Hyde with the car on weekends..
i'd suggest small% Meth blends into E10 pumpCrap
& just read the plugs real quick to check your ECU Tune's High blend tolerance.

BTW: i'm willing to bet a M20 style fuel destroys E85 on the Dyno & on the street..
i specifically had my stock internal SR20DET tuned on a M20 blend
we Spool'd a GT35R by 4800rpm on a DynoJet248
400lb/ft Torque
the Full-race website has dyno charts of GT30's that need their hyped up divided manifolds to spool that Quickly!!
(we used their old undivided type)