E85 tuning notes
 

I'm going to toss all my E85 tuning notes in this thread.

First post covers E85 with my pump gas tune. Not too much to say except:

- E85 makes slightly more power in 80F weather than pump gas makes in 50F weather with essentially the same tune.
- A few times now, I've seen the knock count rise up to 3 in the midrange where its usually quiet pump gas, but then in the higher rpms where pump gas usually gives me trouble, the E85 runs are completely knock free.

- Next step is to lean out the AFR to 11.5-11.8.
- I suspect that I may need to pull a degree of timing out of the midrange.

- I'm still trying to get a handle on the E85 tuning approach. I've read in a few places that timing can be bumped up with E85, but others say timing should stay about the same. Because E85 burns faster, I'm leaning towards the notion that there is little advantage to bumping up the timing.
- The other issue I'm trying to understand is what makes E85 work so well. Its not like race gas where timing can be liberally increased. It has to be that E85 has much more stable burn characteristics.

We saw 23whp at the same boost level from pump to E-85.. Now thats with adding timing and playing with the mapping, not just switching fuels.. The main advatange i see besides adding timing over pump is the cooling effect.. With a stock turbo being pushed well past its efficiency range the e-85 makes more power just on cooling. Even back to back runs we were staying within 3-5 whp..

I'm pretty sure it burns slower, it has an octane rating of 105 which would indicate a slower burn..But from the short amount of time I have spent tuning with it, I can tune close to my 116 octane ig. map..The cooling properties go a long way with this stuff..I am running a pretty substantial amount more timing on E85 then I was on pump gas..I have also found that running it richer allows more timing for me, so I am tuned to about 11.3-11.4 now wheras I was hitting knock on the same ign map running ~11.7..Of course your results may vary{thumbup}

Also, make sure you runn all of the gasoline out of your car before tuning, you first two tankfulls are probably only about E65-e70..

I'm currently at 11.1-11.3 AFR (gasoline AFR). I'm going to try 11.5-11.7 tomorrow. I may move back to 11.1-11.3 and try upping the timing to compare to the 11.5-11.7.

I couldn't find any good articles on flame propagation rate, but mlpspilot found an EPA article that listed E85 has having a rate of 27 cm/s vs gasoline value of 38 cm/s.

https://www.evolutionm.net/forums/sh...81#post5639781

Part of the reason it makes good power is because it's highly oxygenated. It means you can use a lot more fuel. Which means more power. Remember gasoline's lambda is 14.7 afr, E85 is ~9.8. That's 1.5 times the fuel. 1.5 more fuel will make more energy even though unit per unit ethanol has lower energy content than regular gasoline.

We want several things out of fuel - fast burn and detonation resistance being the most important ones. High oxygenation and cooling are other very good qualities. All those make power. E85 exceeds gasoline in all those.




Octane has nothing to do with the burn rate. And your timing and burn speed understanding is wrong if i understand what you're saying correctly :).. If you're saying you run richer to slow the burn so you can run more timing - it doesn't make sense. But maybe i'm reading wrong.

What I meant was that with the higher octane level of E85, it should not ignite as "soon"as 93 octane gasoline in the combustion chamber..
Just going off of context by the OP here

I didn't mean detonation though. I just meant that it burns faster in the context of a normal combustion event.

I fully understand now, and by saying "burn" you were right and I was wrong as I was thinking more along the lines of "ignite"..

I leaned out the AFR from about 11.2 to about 11.6 from 4500 rpm to 7500 rpm and picked up about 10 WHP. I'm definitely closer to the knock threshold though. I got several more counts in my first run than I usually do. Second run was virtually knock free though.

Before
https://www.evolutionm.net/forums/at...hmentid=121303

After
https://www.evolutionm.net/forums/at...hmentid=121304

Up that boost mrfred, if I can run 27.5 psi on 91, you can run that on E85 with real timing. ;)

Run 25psi through the midrange if you can, you will pick up a ton of area under the curve.

Bring it back. Has anyone had Idle issues with E85 and the bigger Injectors? Any stalling when coming to a stop?

Idle on my car is actually a little better with E85 than with gasoline because the pulse width is a little longer. If your car is having a tendency to stall, the first thing I would look at is the idle fuel trim. If the idle trim is say more than +6, then a lean condition could be occurring in some instances when idling. If that's not the case, then perhaps look at bumping up target idle slightly to see if that helps.

I will look at that and I think bumping the idle is needed. The first tune, the idle trim was off. Showed a 0,0,25, after adjusting 0,0,9 and had to re-tune it again. Going to see at noon if the ECU has adjusted any more.

Im still learning alot about e85 as well, but I have read the same thing and seen some good results from advancing on a non evo.

I worked on a project when I was in school, CBR250cc running a turbo with 11:1 compression, and about 10 to 12 psi of boost running e85. I found that my timming in the non boost areas needed to be about 8* to 10* above what I normally ran on the N/A CBRs on 93oct. My timing at start ended up being about 15* over the 93oct , much less than that, it wouldnt start. When I got into boost I decreased timing from my max N/A value linearly with RPM increase and boost increace.

Granted this is a very differant setup from the 4G63 for sure, it revs to 20,000rpm small displacment etc, but I just wanted to share my findings.

I also ran a fifth injector up stream in the IC piping about 15 to 18" away from the ports. This had a HUGE effect on cooling, at idle the intake manifold and piping would sweat. We didnt have a room for an intercooler, so the cooling effect would be even greater with an intercooler.

That's for the feedback on ignition timing at low loads. That's what I'm fiddling with again. I'm back to E85 for another three weeks, ... maybe longer if I can improve gas mileage enough to travel 240 miles on one tank during a road trip. So I'm fiddling again with E85 economy tuning... trying to get a feel for optimum ignition advance during offboost cruise conditions. I tried my current 92 Oct ign advance which has quite a bit more advance over stock and found that the car felt softer with E85 than with 92 Oct. There was virtually no knock with this map except at 70-80 load and 2500-3000 rpm. No matter what I do, the car seems spit out a knock sum of 2 in this range, so I don't worry about it. I pushed up ign advance by another ~2 deg in most all cells up to about 100 load. 15 minutes of driving wasn't enough to be able to tell whether its working. No additional knock though over the previous ign map. This is a situation where live tuning would really be helpful. Here are the before and after maps.

baseline map (my latest pump gas timing map):
https://www.evolutionm.net/forums/at...hmentid=122938

+2 deg up to about 100 load:
https://www.evolutionm.net/forums/at...hmentid=122939