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-   -   E85 and stock fuel system (https://www.miataturbo.net/general-miata-chat-9/e85-stock-fuel-system-19928/)

ZX-Tex 04-22-2008 01:54 AM

E85 and stock fuel system
I have searched and read through some previous posts here and on m.net concerning the use of E85 with a stock fuel system. I found some info here (and a lot of the usual no-experience-speculation on m.net :jerkit:) as to whether or not it is OK to do this. I am wondering if anyone has successfully used E85 in their NB with the stock fuel lines, tank, etc. I am not looking for information on injector sizing, tuning, opinions on whether E85 is worthwhile, the politics of it, etc. just on fuel system material compatibility.

I can get E85 locally and would like to try it out and tune a MS map for it. I am not sure that I want to change out all of the fuel lines just to do this, at least not yet. I have some other things that are higher on the Miata to-do list. Though my car is a daily driver I would not run it every day, just on occasion.


zoom2zoom 04-22-2008 02:29 AM

Interesting, what does it say when you google it with results for other cars?

Savington 04-22-2008 02:56 AM

I doubt running a few tanks through will harm anything. I would change your fuel filter, make sure everything is up to date, etc. Sounds like you know about the increased fuel requirements, so good luck and let us know how it goes.

elesjuan 04-22-2008 06:16 AM

I asked a few months back if anyone ever came up with fuel and spark maps for E85 and boost that I could start with but came up with nothing.

A quick google search offered me this little snippet, which I take with a grain of salt:



Yes. However, there is no conversion kit certified by the EPA that meets the standards to maintain clean exhaust emissions. Technically speaking, converting a vehicle that was designed to operate on unleaded gasoline only to operate on another form of fuel is a violation of the federal law and the offender may be subject to significant penalties.

The differences in fuel injector size, air-fuel ratio, PCM calibrations, material composition of the fuel lines, pumps and tanks are just a few of the components that contribute to making an E85 conversion extremely complex.
As for the composition of fuel lines, tanks, etc, yes they're different. Ethanol is a very corrosive material and that large percentage of it might do bad things to your fuel tank and or fuel lines. From my research ideal conditions would be a composite ABS fuel cell type tank, Ethanol safe pump, AN fittings, and stainless lines. All rubber aluminum or non-stainless steel lines need to be replaced. That makes me wonder if the Russel TwistLoc lines for AN fittings would be sufficient? Haven't seen any data on that yet.

While I understand energy consumption for production of ethanol is significantly higher than gasoline, trends have shown in my city that 85% Ethanol 15% Gasoline mixture sold at a fueling stations is around $0.70 a gallon or more cheaper than straight gasoline, along with the ~ 110 octane rating peaks my interest in utilizing it in a performance automotive. Matter of fact, theres a 500rwhp MR2 running around here on E85.

sotaku 04-22-2008 07:50 AM

I've been thinking about doing something like this on my 97 (though I'm not sure it's possible on the NA, though I've heard by the time OBDII came into play most fuel systems were ready for ethanol.

The > 100 octane rating is fantastic, though it does fluctuate throughout the year since the mixture changes. However MSII can take input from a FlexFuel sensor (which looks to be a fairly simple thing to install) so this becomes moot and you'd even be able to put gas in it when that's the only thing about and E85 when you have access to that.

Fuel economy I understand will go down quite a bit - but somehow I don't think we're in it for that. =P

ZX-Tex 04-22-2008 10:54 AM


Originally Posted by zoom2zoom (Post 245723)
Interesting, what does it say when you google it with results for other cars?

I was hoping for some experience specific to using it in a NB Miata. To answer your question I have found lots of general anecdotal information on using E85 in vehicles other than Miatas.

That being said, if one were to assume that the fuel system uses the same materials as a Honda or a Subaru (WRX STi) then it is probably OK. Here is a link that has some interesting information, including links to more sites with more information. From what I see people out there are putting it in their turbo Hondas and Subarus, retuning AFR and timing, and having a good time.


cjernigan 04-22-2008 11:02 AM

1badmx5 (forum member) ran E85 in his NB. He eventually upgraded his fuel system is crazy fashion with all AN lines, surge tank, and extra fuel pump but he might have ran it prior with the stock system as well. Worth sending him an email anyway.

wildfire0310 04-22-2008 01:51 PM

There was a guy on the supra forums talking about how he ran E85 in his car and was building his supra to run on it.

He said you could run it on the stock fuel pump but recommend that you swap in an aftermarket pump. He said most cars the stock lines are fine for running E85 just have to watch the hoses in the engine bay, and he again recommend replacing them with newer ones before hand. He said he used stock injectors on both the supra(before been rebuilt) and on his ford escort. He did say that since you have to run a new fuel map with 20% more fuel that if you think you already pushing your stock injectors to swap to bigger ones to be safe. Again he was on a supra board so just like use thats more for cars with mods. He said he was using the stock injectors in the escort without any issues. I believe he said he had an e-manage blue on the escort.

Prospero 09-25-2008 12:54 PM

Hmm, so i never thought i would jump on this boat... but we now have E85 in my neighborhood for over $1.25 less than 93 octane...

Since i have larger injectors and an AFR / 02 clamp / FMU... i think it's worth a shot to try.

Will let yall know what happens when i run a few gallons over the weekend.

Who want's to place bets on the result? Shall I carry a mop and dustpan in the trunk or what?


paNX2K&SE-R 09-25-2008 01:03 PM

There is a great thread over on NASIOC regarding using e85 in standard fuel cars. An engineer from Walbro did some fuel pump compatibility testing and there is lots of other useful info there too. I use e85 as an octane booster in my SE-R, about 30-35% ethanol when I go to the track.

Splitime 09-25-2008 02:01 PM

If you want to be sure. Grab a few glass jars... buy some e85... buy some common fuel system seals (should be cheap to grab)... dump them into jars of e85 and let soak for long period of time.

Local shop (AMS) had jars on a shelf for like a year just to double check long term usage of e85 in their Evos.

If the seals come out swollen or fragile... don't use it ;)

Miatamaniac92 09-25-2008 09:34 PM



944obscene 09-25-2008 10:37 PM

E85 can be compatible with the Miata...

ZX-Tex 09-25-2008 11:11 PM

Perhaps you did not read in my post above that I am not interested in opinions on the pros and cons of E85, just its compatibility with a Miata. So let's keep this on topic.

Slider 09-25-2008 11:32 PM

A lot of the DSM guys are running it on stock lines. Haven't heard of any problems. I would venture over to the DSM forums they have people that ran it like that for over a year or two. You can probably find some info on their forums dsmtuners.com dsmtalk.com

Miatamaniac92 09-26-2008 01:32 AM


Originally Posted by ZX-Tex (Post 245712)
I am not looking for information on injector sizing, tuning, opinions on whether E85 is worthwhile, the politics of it, etc. just on fuel system material compatibility.

Should be compatible with the fuel system.

I'll probably run a gallon next time I go to the track for some detonation insurance.

My long term goal is to MS and hook up a Flex Fuel controller.


944obscene 09-26-2008 01:47 AM

There should be a list of materials that aren't compatible with e85. Why not look for answers on Google? I wiki'd e85 and found an article talking about its pro's and cons as well as giving a general explanation of it. Sounds like cork and natural rubber as well as exposed aluminum and a couple other things don't work well with the ethanol content in e85. Thus, you need to find a list of materials found in the fuel system and in the motor, to see if there is anything that won't stand up to moderate amounts of the stuff. I'd give Mazda a call and see what they can say. They will probably tell you they "don't recommend it". Or go hit up a dealer and find out the materials in the fuel system with them.

I know Wikipedia doesn't mean dick to some, but the info is there to read. Double check anything that sounds sketchy to you just to make sure.


elesjuan 09-26-2008 02:08 AM

Another honda friend ran E85 constantly in his 98 Integra with factory fuel system parts (upgraded flow pump, fuel rail, pressure regulator) but the rest was stock.

I'm still highly interested in this, but am not willing to replace my fuel system to use it yet..

Stephanie Turner 09-26-2008 12:39 PM

markp ran E85 in his 99 car. It will lower your stoich tuning #'s. But otherwise I think he did not have any problems. Might want to ask him though.

BoostCreep 09-26-2008 01:03 PM

I'm really interested as well. It would be much cheaper than buying 100octane or mixing in Zylene to the shit 91octane we have at our pumps.

I have friends that have switched and tuned their pre 94 240sx' to E85 and have reported cooler running engines and one person is getting 70ish more hp out of his as he can run more timing per given boost. Of course they're on stand alone systems.

I think in the long run, it's less cost but less energy per molecule, but it's detonation tolerance may be worth it.

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