Can E85 technically work? - RX8Club.com

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Can E85 technically work?

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Old 08-16-2015, 07:19 PM
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Can E85 technically work?

Okay, hear me out. I know this topic has been discussed. I searched the forums, but hear me out.

a fellow canyon buddy, has a 2007 Acura RSX. He is running only E85. When asked how he accomplished this, he said, all he did was add "hotter spark plugs" (spark plugs that run at higher temps I am guessing) and "larger injectors". Nothing else. He didn't touch his fuel tank, he didn't tune his ECU, he didn't do anything other than those two things. He has been like this for a few years now, his car has never exploded, engine hasn't died on him, in fact his car is super freaking fast. I don't know what the engine block is made of on the RSX, but if its aluminum then that's the same as the RX8.

If say, someone did the same thing, just add larger injectors and hotter plugs (maybe something for boosted RX8's) should that work the same as his? Would the computer "learn" and adjust accordingly? I know I know, the rotory engine isn't a regular engine found on the RSX, but if he found success on simple part swaps, what's to say the same won't happen here? My car has 80k miles, maybe I will take the plunge, and try since I could theoretically be near the end of the engine life.
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Old 08-16-2015, 07:43 PM
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You need a special, purpose built sensor to detect the presence of e85. You also need an E85 map, to take advantage of it. E85 is more resistant to knock, so you can run higher boost and more agressive timing. It is also, however, less energy dense than gasoline. Meaning you need MORE E85 to achieve the same burn energy as an equivalent amount of gas.

On top of all this, you must be very careful when selecting fuel components. Not all materials can handle ethanol, some will be dissolved by it. A trashed fuel system will not get you anywhere.

Your friend is an idiot, plain and simple
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Old 08-16-2015, 08:14 PM
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I'm guessing if he tuned it properly he would be making more power, but I drove his car, and it didn't idle weird, it didn't run rough, it pulls like a bat out of hell. He takes about 20 gallons when he goes to the track, and uses it all, so he is aware of the fact that it gets worst MPG. I'm just curious as to why his engine or fuel components haven't blown considering he's been running it like that for 4 years now.

Not saying you are wrong, but I was under the impression (based on threads that I read about via me quest for E85 on this car) that majority of components now are days, can technically handle E85 to some degree??
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Old 08-16-2015, 08:39 PM
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Some complements can, but unless the manufacturer says they can, I wouldn't chance it. A dissolved fuel pump gasket could ruin your track day.

I'm sure it runs and drives fine, but without a tune to take advantage of the higher octane (more boost / more timing) he is just wasting time and energy. The high boost guys can use it to their advantage, but it takes more than just a drop in.

I'm sorry I called your friend an idiot. It's easy to get carried away behind a keyboard. It makes you feel anonymous.
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Old 08-16-2015, 09:02 PM
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Nah it's cool, like I said, canyon buddy, not friend.

At track day, he was hell bent on adding 10 gallons of pure E85 to my gas tank. I didn't let him of course.
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Old 08-16-2015, 09:52 PM
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I think your buddy is lying, have you seen him fill up with straight E85?
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Old 08-16-2015, 10:42 PM
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Does anybody in this thread know what they're talking about?

To run E85 requires using about 40% more fuel. If he installed 40% larger fuel injectors it would accomplish the same thing as increasing the fuel map figures by 40%, decreasing the injector sizing in the software by 40%, etc. This assumes the rest of the fuel system can handle the higher flows required.

The bottom line is in the RX8 to use E85 requires making changes in the fuel system or PCM software to do so. In general you won't see much benefit and your fuel mileage will drop by 40%. It's pretty much a racing only modification. You could use it as a track only mod if you have the ability to change PCM software tunes between gasoline and E85 use.

Again, unless your engine is operating near 100% potential the benefit in an RX8 Renesis is very small ...



.

Last edited by TeamRX8; 08-16-2015 at 10:47 PM.
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Old 08-17-2015, 01:09 AM
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Originally Posted by 9krpmrx8 View Post
I think your buddy is lying, have you seen him fill up with straight E85?
Yes sir, I held the funnel as he poured it into his gas tank. Considering it smelled absolutely nothing like petrol, and more like sweet corn vodka or something, I would say definitely wasn't gas.
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Old 08-17-2015, 01:31 AM
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Tell that dumbass that he will end up blowing people's engine's up (rotary or piston) if he insists on running e85 in a car that isn't tuned for it. It'll make it run super lean. If you had let him put 10 gallons in your car there's a high chance you would have lost the motor.

The reason why he hasn't blown up his car is because the bigger injectors were enough to keep it happy, and since he didn't touch the timing it's probably conservative/safe, also he's probably not making any more power than he was on pump gas since AFR is not tuned and timing is untouched.

You can use e85 on an RX-8 just fine, most naturally aspirated cars that convert will gain about 5% power and exhaust gas temps go down which is good. At a minimum you would probably want slightly larger injectors and fuel pump and it absolutely has to be tuned on e85, and if you premix you can only use alcohol specific stuff.

Also what BigBadChris said up there, you don't NEED an ethanol sensor to run an e85 map. You only need that if you're going to run a flex fuel system than can adjust for ethanol content on the fly.

Last edited by Arca_ex; 08-17-2015 at 01:34 AM.
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Old 08-17-2015, 08:23 PM
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we switched the race car over to E85, and its been interesting. i think (<-key word) that E85 would be good in an Rx8.

here is the boilerplate disclaimer. we're running an NB miata with a 2001 engine, the fuel system is 100% stock, but we do have an ECU to tune it with. we have done 7 or 8 dyno days this year, about half of those have been with E85.

so here is the good stuff.

we made more power, pretty much everywhere, peak is up by 10hp, which is a lot in a miata.

it runs cooler, we have a hard time getting it up to temp.

it seems less sensitive to AFR and timing, we're only allowed 134rwhp, and the car makes 144, and we tried adding fuel and pulling timing and it didn't do much. we eventually had to run an intake restrictor, and play with the cam timing.

mileage is worse, but not by as much as we thought it would be. in fact if we didn't know to look for a mileage change we might not have noticed. i'm sure the rotary would be different.

to sum up, E85 seems to offer several properties that would benefit an Rx8, even a non turbo one.
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Old 08-19-2015, 02:30 PM
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If I were to use E-85 I'd just set the injector size to offset the difference and tune like normal. It would probably be ok to swap back and forth using two different tunes. Just drive it down to 1/4 tank on gas, flash for E-85 and let fuel trims fudge the rest, then do it again on the reverse end.

25% LTFT gives you a lot of wiggle room both ways.

Not saying it would work well, but on paper it should, and that's the way I'd try with the stock ECU. Oh and on the same note, there are interesting ways with fuel injector sizing and MAF cal to get around load limits.
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Old 08-19-2015, 09:58 PM
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This has no bearing on the Renesis, but...

One of my employees has a Saturn Sky turbo. He moved to E85 the right way. That involved replacing both fuel pumps, the injectors, the cam shafts, and the intercooler (optional), and installing a base tune. From there, he had the car dyno tuned. He gained about 30HP and 50 ft/lbs of torque. His total cost was around $3K IIRC. Not too bad for what he gained.

The point is, you have to do it right. There is a lot to consider. Half-assing it is a good way to lose an engine.
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Old 08-20-2015, 12:12 AM
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This does have a bearing ...

If you'd have bothered to search 'E85' on this forum first along with some reading you'd have gotten the right information and also realized there wasn't any need to start another thread on the subject
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Old 08-20-2015, 06:51 PM
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Originally Posted by TeamRX8 View Post
This does have a bearing ...

If you'd have bothered to search 'E85' on this forum first along with some reading you'd have gotten the right information and also realized there wasn't any need to start another thread on the subject
i did the search you suggest just out of curiosity and not much relevant info comes up.

although you are kind of right, changing to E85 was actually pretty easy

humorously doing the search i did learn that its feed corn vs food corn, and that "alcohol melts aluminum so you cant use it in a renesis" because the renesis is made of iron.
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Old 08-20-2015, 08:24 PM
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for sure, just as in this thread, there is more incorrect than correct info here, but there are one or two good threads
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Old 07-05-2018, 08:38 AM
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bringing this post back since its the most recent post i found on E85. has anyone been running e85 for awhile? I ran e85 on my Evo and loved it. gained a ton of torque, engine runs cooler, minimal carbon in the engine and exhaust. consume about 20-30% more fuel, needed larger pump and larger stainless injectors, so they don't rust out if I don't drive the car often.

are there any issues with running premix and e85. i have SOHN adapter and also run premix at the track.
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Old 07-11-2018, 04:12 PM
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Hi Everyone,

I will be doing a back to back dyno on my car - we will be tuning the car on 91 pump gas that usually has around e10 inside of it. Then we will be going back to the pump and filling up with pump e85 (65-85% ethanol)

The car has around 85psi compression on each rotor (cold/hot starts fine)

The car has the following mods:

Full exhaust including a header - no CAT
AEM intake
Adaptronic Rx8 PnP ECU
IGN-1A ignition coils with MSD coil wires hand made by me.
Stock Rx8 Spark plugs - I will have a set of r7420-11s to test with as well
Fuel pump is stock atm but I am thinking that I will drop in my Aeromotive Stealth 340

I will be data logging A/F on each rotor, EGTs on each rotor, and back pressure

Dyno Day is on Tuesday the 17th

Cheers,

Shawn Christenson
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Old 07-11-2018, 04:33 PM
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Very nice. Looking forward to results.
Are you running stock Injectors also?
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Old 07-11-2018, 05:17 PM
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Originally Posted by trackjunkie View Post
Very nice. Looking forward to results.
Are you running stock Injectors also?
Yes - will post up injector duty data as well when we are done.
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Old 07-11-2018, 05:27 PM
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Nice, would be great if a drop in fuel pump is enough, without bigger injectors.
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Old 07-18-2018, 01:57 PM
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Hi Guys!

I got to do a baseline with my Rx8 today with 91 Octane pump gas - (less than 3% ethanol) in the fuel.

Unfortunately the dyno kept cutting out... and I couldn't see if I was making consistent gains between changes.

Best RWHP I saw was 184
Best RWTQ I saw was 134

I think with a properly operating Dyno and some more seat time I can bump the hp higher on pump gas.

Stock port engine
Full exhaust
AEM cold air intake
IGN-1A Ignition coils
Adaptronic PNP Modular ECU
Klots Super Techi Plate Pre-mix 1.2/1.5oz per gallon of gas (still have the OMP as well)
Stock injectors
Stock fuel pump

So after the Dyno I filled up on e85! This is very simple with the adaptronic ECU that has a flex fuel sensor. I simply pumped the gas in and drop off.. No changes needed to be made.

Iv done some pulls on the street now and here are my current results

RPMs 8643
AFR 11.7 (rich)
Fuel Pressure 56.5
EGT Rotor 1 - 1393
EGT Rotor 2 - 1373
Primary Injector Duty - 71.18%
P2 Injector Duty - 99.99%
Secondary Injector Duty - 53.16%

Only other changes from yesterday is I did install a new air filter the previous owner of the car had the last one on for like 50k miles.

I am excited to hit the dyno again and see what we get with the ethanol! The car feels soooo strong!

Honestly you do not need to upgrade your fuel system to switch to ethanol!!

Thanks,

Shawn Christenson
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Old 07-18-2018, 02:10 PM
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Even if the stock system can handle the flow, I'd be curious if all the seals hold up against such a high concentration of ethanol. That's something to consider.
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Old 07-18-2018, 02:58 PM
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Originally Posted by UnknownJinX View Post
Even if the stock system can handle the flow, I'd be curious if all the seals hold up against such a high concentration of ethanol. That's something to consider.
It cleans your engine! Take note I am heavy premixing due to the lack of lubrication ethanol brings to the table.
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Old 07-18-2018, 06:13 PM
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Originally Posted by shawnm565 View Post
It cleans your engine! Take note I am heavy premixing due to the lack of lubrication ethanol brings to the table.
Doesn't address the possible seal issues, though.

Ethanol is an excellent solvent that dissolves fuel system components. Ethanol can dissolve rubbers, plastics, some fiberglass's and even aluminium. The rubber that is used in fuel system parts like seals and hoses may shrink, lose strength and become brittle.
Also, I remember that most premixes don't like ethanol fuels. Good to double check that.

Last edited by UnknownJinX; 07-18-2018 at 06:15 PM.
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Old 07-19-2018, 10:25 AM
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Originally Posted by UnknownJinX View Post
Even if the stock system can handle the flow, I'd be curious if all the seals hold up against such a high concentration of ethanol. That's something to consider.
are you talking about the fuel lines and seals? pretty much all newer cars fuel system can handle e85 since pump gas has up to 10% ethanol.
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