Ethanol blends
 

A few of us are running different blends of ethanol now . Thought it a good idea to try keep the discussion in one place for future reference.

I just switched over to E50 yesterday and ran the tank through . Mileage was about 15% less than normal as expected.
The thing I noticed was that my fuel gauge was acting strange . 4/4 to 3/4 seemed about right but 3/4 down to 1/2 went exceptionally quickly . The 1/2 down to 1/4 was the other way around ... took twice the kms . 1/4 down to empty then went really quick again .
Anyone else seen anything like this ? I suspect it may be to do with siphon mods I made to the fuel pump assembly not working well with the new fuel.

I have not noticed anything with the gauge other than the fact that it goes to empty faster, :lol:

Assuming min is actually close to E85 (which I am now doubting), I am running about a E25 mix now.

I went from E25 to E50 . I never noticed anything unusual with the gauge on E25 .

I would expect that one side of your fuel level sender is acting up...

Yeah ... maybe it's just a coincidence it happened after the switch ....

Impressive - did you have to change any elastomers in the fuel side piping, seals, and the like. Also how do you keep water out to prevent any rusting of metal parts in the fuel system?

I've not experienced that phenomenon. My first 1/4 tank takes the longest to go through but it was the same regardless of ethanol blend. Of course, higher percentages went faster, but relatively speaking the gauge behavior was the same.

No ....plenty of people are using this without need for modding the fuel system .
I do have a DW300 fuel pump which is advertised as compatible .

As far as keeping water out ..... I suggest leaving the gas cap on ........:yesnod:

Yeah I did a lot of research and pretty much the consensus is that most modern cars were made with the knowledge that Ethanol would be in the fuel so there is really no need to make anything "ethanol compatible". In the BMW 335i world, people have been running E85 mixes for long time now without any corrosion issues from running E85 mixes. I have not done an E85 tune on my 335i and have only been running it for a few thousand miles on my RX-8 so we shall what my personal experiences are in the long run. I run the Walbro pump, it has about 45,000 miles on it.

I'll need to do more research My understanding was that lower levels of ethanol are fine ~E25 but the water absorbing and water holding capacity of ethanolic fuels leads to corrosion of fuel delivery and exhaust. The fuel stability is another question since water increases fuel oxidation to "fatty" acids. The biofuel (and fats and oils industry) go to great lengths to keep water out. But once the fuel leaves the refinery, contracted distribution may not do everything in their capabilities to keep water out.

What changes do cars require when they inject water into the combustion chamber for the injection through exhaust systems?

This product: Ethanol Shield Fuel Stabilizer | B3C Fuel Solutions is suppose to be pretty good at preventing that.

The company also makes it mixed with 2-cycle oil.

This is a mixture of Solvent naphtha (petroleum) and medium aliphatic
Distillates hydrotreated with afew other trade scret additives and is a different blend that would be used for normal < E25 gasoline stabilizers. It also has a few other additives to help prevent fuel seals and pipe elastomer seals from dry rotting (leaching of plasticizers in the seal compounds).

The fuel stabilizer mentioned above is preventing moisture (water) attack on the fuel itself caused by ethanol. Methanol (IsoHeet) works differently in that it uses methanol to solublize the water into the fuel phase to keep the old gasoline from separating and forming a water/gas layer that turns to varnish due to oxidation of gas by water and dissolved air.

None of this makes me feel good (as a chemical engineer) that high ethanol blends are good long-term for a car that was designed for < E25.

All correct, except that IsoHeet is isopropanol - methanol is not an acceptable gasoline constituent.

I just did a ton of reading (mostly on the rx7 site ) .
After all that I'm now more confused than before I started . There is so much conflicting information that I can't decide who to believe and if there are real issues I should be concerned about or not.


Some things that did seem to be worth taking note of :
*I could find no talk of corrosion to fuel system over on the 7 forum .
*there is a need to change the oil more often
*There is a need to use compatible premixes should you be using premix (I don't)
*There is a need for increased oiling if not using extra premix.
*There is risk of clogged fuel filters should you be switching from a setup that has had many years running petrol.
*nobody seems to be running fuel stabiliser.
*Aside from all that there seems to be many positives to running ethanol.

Final conclusion is :

F*** it , keep going and see what happens !


About the biggest issue I've had since switching to E50 is the reduced range from a tank . Going to E85 doesn't look like a good prospect for me for this one reason.

Also : gunna have to switch to larger injectors as I've had to reduce boost down to only 14 psi .

Oh it definitely hurts the tank. If I had to guess, I would say I am getting less than 10mpg.

And yeah most of the info is fawked. All I know is that on other platforms there has been no confirmed corrosion issues, even from the guys running full E85 for a while now. I am sure every platform varies but when I see corrosion issues, I will worry about it then. I just wish I could mix on my own.

what do you mean ?

You could mix your own if you can purchase ethanol for personal use with an A.T.F. "license". Businesses who use "pure grain" for making products use specially denatured (to prevent drinking). https://en.wikipedia.org/wiki/Specia...atured_alcohol

Well I can mix my own, it will just be a hassle. But I mean getting true E85 from VP fuels (local to me) and mixing it. The E85 available to me seems to change quite a bit. My BMW can account for it with the JB4 (piggy back) but in the 8, if it's in the E50 range it doesn't run well.

A couple of the local EVO guys I know test it quite a bit and the range is anywhere from E50's to E70's.

Is it safe to run blended fuels in these vehicles? I hadn't done so because I wasn't sure.

At the station I go to there is an E10 pump right next to the E85 . I just do a 50/50 mix from those which gives me approx. E48 . I rang the supplier who assured me the E85 stays within a few % of 85% at all times .

I'm getting maybe 290kms /55 litres around town and 330/55 on a trip . So around 12.5 and 14 MPG . But I'm working on leaning out the cruise maps a little to try improve that .

That is what the discussion is about ............

How are you achieving this - Closed Loop Fuel Correction maps? I was hitting some higher than Stoichiometric AFRs during low load while I was sorting out my injector latencies, and drive-ability seemed fine. My mileage is terrible compared to most rx8s (330km per 55 litres on standard gas). I think Fazda did some lean-burn testing at some stage.

That is the plan.


In the meantime , I just pulled the injector on the left out of P1 position that has run at various ethanol concentrations over the last 6 months. As you can see, there is a definite discoloration of the plastic cap . The other injectors I pulled from the P2 position didn't look so bad .
I also noticed that the 'o' rings on the injectors were loose . Not good signs for the long term perhaps ?




https://cimg7.ibsrv.net/gimg/www.rx8...bdffbbdfef.jpg

I'll have to look at my old injectors but I am pretty sure they all change color like that over time. I have a shit ton of yellows, I will look at them tonight.

I'm just saying...the American Motorcycle Association is working hard to prevent E15 fuels from becoming available due to the many corrosion and seal/gasket failures that pre-200x bikes would have issues if the EPA moved to E15 fuels. I'm not sure of the LT stability of the seals and the metallurgy in mixed metal fuel and engine systems with so much ethanol (and water vapor / kg mass of fuel) generates.

I believe mine had similiar discoloration as well - prior to running E50. I'll look when I get a chance.

It is already available and has been for some time. They are fighting a losing battle.

I also have similar cap discoloration, and never used an ethanol blend.

When I had issues with leaking injectors it was always from the smaller seal at the top end where it seats on the rail, not the larger one close to the nozzle. Not to say you wont have issues, just some feedback. Brettus, perhaps you could do a test by leaving a spare seal soaking in some E85 for a few weeks and see if it comes out weaker.

The first photo is of two relatively new injectors that saw E50 for a couple months. The rest of the photos are old injectors that never saw more than E10.


https://cimg7.ibsrv.net/gimg/www.rx8...5a250eca7d.jpg

https://cimg8.ibsrv.net/gimg/www.rx8...ff7e493b5e.jpg

https://cimg9.ibsrv.net/gimg/www.rx8...a345920fd5.jpg

https://cimg0.ibsrv.net/gimg/www.rx8...463b8ea6b3.jpg

So do you guys just not have the fuel system capacity to run e85 or what's the deal here?

Straight E85? Even if you could tune for it no way I don't think without significant fuel system upgrades. My 335i will need port injection to handle full E85 and high boost.

For me it's more about the size of the tank and how far I can get on it . E50 seems to be a good compromise between ultimate knock resistance/power and range .I feel that I would have to go to another round of mods to run E85 at my power level as well .

Just retuned on E50 after fitting larger injectors and everything seems ok on the stock system (with uprated pump and injectors) to 16psi/400+whp ...................... so far.

Brettus, what injectors did you go for?

Blues in p1 then 4x uncapped yellows.Seems to work well . Took about an hour ;)

This may be a dumb question but I have plenty of them.... Since carbon is a common problem with the 8 and ethanol runs cooler than 93 octane, do you guys run into any carbon build up issues going with the e25/e50? I'm assuming the frequent redline helps prevent carbon build up like usual.

I doubt the amount of cooling is enough to make any difference but theoretically ,as ethanol burns without deposits, there should be less carbon deposits the higher in ethanol % you go.

Makes sense. I've been doing a ton of forum reading the past few weeks. I'm getting ready for a turbo swap in my newly acquired shinka. It's been molested by the previous owner (87 octane pure gas, dumb old lady). The thought of e85 turbo pleased me but it seems the fuel delivery isn't enough really worth the effort. The e50 has my interest though.

You will be struggling with E50 on the stock system as well .

This was the conclusion I came to as well... :icon_tup:

I'm with brett and Slash on e50. you get the important benefits of e85 for a street car. I think going full e85 would be more beneficial on a track car as going full e85 adds more combustion cooling benefits

Do you think the seals will hold the high amounts of boost that ethanol can provide, like 18+, or will detonation occur before we reach these levels?

@9k How much boost are you running if you don't mind me asking?

I know 9k isn't much of an Atkins fan but with the E50 is there any need for cryo treated parts?

Of course ...that is mostly the point of using it .

I am running 10-13psi at the moment.

what octane rating do you guys get on E50 and E25 blends respectively?

Have a read thru this attachment.

TL;DR:


https://cimg3.ibsrv.net/gimg/www.rx8...4f9b6d4aef.jpg

It's not really fair the put E85 on the traditional "anti knock index" that gasoline is graded on here in the US.

The evaporative cooling properties and cooler combustion temperatures of "alcohol" fuels is a big part of its knock resistance. Good E85 can hold its own even against 105+ octane race gas.

I'm no expert, just sharing what I found. They do discuss cooling effect in the paper, IIRC. What I can tell you from my own personal experience is that I ran E50 up to 12.5 AFR at 15psi or so with no perceptible knock. So for a street car I was happy with the benefits of E50 without taking quite the MPG hit of E85 :)

So I've agonised over this a lot and finally came to the conclusion that E30 with oem seals is the way to go for a high power Renesis for these reasons:


*good octane boost taking 93 octane E10 to 96 octane (101 octane for us in NZ)
*good charge cooling eliminating the need for W/M.
*Engine and intake should stay clean and carbon free.
*reasonable mpg .My research suggests 20-30% is the best ethanol level for mpg. Some piston engines are getting same mpg as straight petrol.
*Easy to work out at the pump , 1 part E85 to 3 parts E10 gives E29. Should also mean I can easily carry extra E85 should I want to travel far from a pump.
*Good wear characteristics for a long engine life with the oem seals . Octane and charge cooling effects should minimise the possibility of apex breaking detonation events . (I had excessive wear with E50 and an aftermarket seal combo.)

I'll also be running an AEM failsafe guage to minimise the possibility of a leanout event killing the engine.

Curious - if E10 requires a lower air:fuel ratio at stoichiometric than real petrol, how does the ECM know this and adjust? Is it the O2 sensor that corrects - preventing a lean burn situation or loss of power?

O2 sensor reads Lambda.....so it doesn't care what Stoich is..... O2 sensor allows for fuel to be added or subtracted up to ECU limit of trims to get it right.