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.