I see a lot of way misinformed anti-E85 propaganda anytime I try to research it on a VQ board. It seems like a lot of people are blindly convinced that this stuff is the devil. I decided to share my real world experience with it in my basic bolt-on G35.

I've been running E85 for about 5 years in Miatas and I've had great luck with it. In my experience it's made great power and it's cheap enough that the cost per mile actually works out cheaper than 93. My miata saw a 17% loss in fuel economy on E85 that's consistently runs 30% cheaper than 93 octane in my area.

My G35 is my "dad car" we got when my wife was pregnant. I was supposed to leave alone, but I can't help myself. It's got basic boltons now; osiris tuner, testpipes, catback, ztube, and a plenum spacer. I don't have any crazy expectations, but I'm hoping E85 will help to gain a few hp and make the stinky testpipes smell better.

 

I've been street tuning cars for +10 years. I'm certainly no expert but I've got a pretty good grasp of the basics. With that said, I'm a total noob with Osiris, it's a lot different from other programs I've used so any advise constructive criticism is certainly welcome.

It looked like I was going to need to upgrade injectors for E85. I found a set of low mileage G37 injectors on Ebay for $82 shipped and bought them, they're supposed to be right at 30% bigger than stock so that worked out well. They dropped right in and I retuned for the extra fuel.



Once I was happy with the tune on 93 octane on Map 1 with Osiris, I rescaled the other 4 Maps. It's pretty common knowledge that you need ~30% more fuel with E85. I rescaled the other fuel maps with:

Map 1: 93 tune
Map 2: +5% fuel
Map 3: +15% fuel
Map 4: +25% fuel
Map 5: +30% fuel

This, in theory, lets me run full E85 on Map 5. A 50/50 mix on Map 3. And I will use Maps 2 & 4 when switching fuels and there's a couple gallons left in the tank when I refill.

As I mentioned before, I've got a turbo miata that also runs E85. It's got a flex sensor that I can check at any time. The E85 station close to my house has been super consistent with their fuel, so that's not a huge concern to me. I've also got a wideband in the car that I'll keep an eye on anytime I refill.

So anyway, I topped off with E85 for the first time this afternoon. I switched to Map 4 and the car fired right up and ran remarkably well. I've still got to make some adjustments to the tune but looking forward to continuing to update you guys.

 

Go to the DYNO!

 

Nice to see some more updates and thoughts for this!

 

I use Virtual Dyno (virtualdyno.net) religiously. I've got a nice long flat testing road that I make pulls on that have given very consistent and repeatable numbers. I took several 93 octane datalogs that are ready for comparison as soon as I get time to make some E85 pulls.

 

I'm about 200 miles into my first tank since filling with E85. It's about 75% E85 and 25% E10 93 that was left in the tank.

I've been really impressed that the car starts up just like stock, which was one of my biggest concerns.

I finally got a chance to datalog a couple clean 3rd gear pulls and overlay it with my 93 octane pulls. The results were pretty underwhelming really. It looks to me like E85 may have gained a little bit, but not enough to be conclusive from a datalog.

E85 in Red, 93 in Green


I'm going to keep messing with it and I'll continue to update. I'm looking forward to seeing what happens with gas mileage but it's going to take me a while to get any kind of relevant data on that.

 

Very interesting read. I also own an 06 GTO and there are a lot of members that have gone FI on E85 and they are very happy with the results. Sub'd for more info........

 

E85 is good. Planning on running it this year.

 

FI is where you see the huge benefits. You can run so much timing with E85 my last miata picked up around 40whp and some significant spool too. I was hoping for better gains NA but so I haven't seen anything.

I just filled up today, I'm around 500 miles on E85 now. Gas mileage has definitely taken a hit. I've been averaging about 18.5 mpg on 93 octane (heavy traffic commute and I drive like an ***). Today's fill up was 210.5mi / 13.6g for 15.5mpg. So I lost 16% fuel economy. E85 was $2.05 compared to 93 at $2.79; so E85 is 27% cheaper. Dollars per mile E85 has worked out cheaper on every car I've swapped.

I'll try to get some more dataloged pulls for some more HP numbers for a final power update, but not expecting much. I'm loving that corn smell, so that's certainly another benefit (especially with testpipes).

 

Subd great info!

 

Just checking in again for an update. I just rolled 111k miles on the odometer after swapping to E85 at 108k. Car is still doing fine and haven't had any issues.

I drove up to the drag strip to watch a friend run this weekend and I couldn't help myself. The place was packed so I only got 2 runs in. I've got a whole list of ricer excuses; too hot, clutch slipped, old crappy tires, etc., but I ended up running 14.1@98 on my 2nd pass (after a 14.6@97 1st run). Not really sure what people typically run, but I felt like it was a pretty solid time for a basic bolton '04 G-sedan. I definitely feel like it's got 13s in it if I had a few more shots at it (and/or colder weather).

 

Ha hell yeah man. Keep us updated.

 

I live in ft lauderdale area with a 03 g35 coupe headers test pipe plenum spacer intake and i wanna tune via someone local who likes to mess around a bit I saw you were messing with mpg and the funniest part is I want a mug tune on full e85 lol you see these gas prices these days 🤣🤣🤣 I have injectors and fuel pump ready to go in im trying to tune by may hopefully!!! Help me out brotha please 😭?!

 

no official partnership, but I can highly recommend [Z] Fever Racing in Tampa Florida. They are exceptional knowledgeable about our platform and can tune E85 easily.