E85 ignition timing? Would like a general idea of what to aim for.
 

I understand that you can add ignition timing to boosted cells when running e85 but what I am wanting to find out is ignition timing for the non boosted cells. I just recently read that e85 timing in the non boosted areas such as cruising would require to retard the timing some. Is this right? So is it somewhat opposite compared to pump gas? Or can I leave my mild spark map alone in the non boosted areas and just worry about the above 100kpa? I have looked around on here and I admit I'm terrible at searching but I could not find anything that mentions retarding the timing for low load.

Cliff notes: If you are picking up power, you can keep adding timing. If you stop picking up power (even in the non-boosted areas), you stop adding timing and back off. If you don't have the means to measure power output precisely to do any of what I just said, you leave it alone

ok fair enough. I'm not going to go crazy with timing starting off. Do you think virtual dyno could be used as a good tool to determine the gains and where they stop? I'm not looking for max gains really but I wouldn't want to try something like this if it isn't a good way.

I dug up some virtual dyno results I posted from several years ago. I street tuned my fuel map (on Braineack's basemap timing), logged a pull driving to the gas station. Filled with E85, added 30% fuel and 5 degrees of timing, and took a datalog on the way home. Ran both the logs through virtual dyno and got:

93 Octane: 205hp/182tq
E85: 238hp/212tq

https://www.miataturbo.net/dynos-tim...-vd-log-94954/

I swear by virtual dyno. Just make sure you find a flat stretch of road and log a few pulls to make sure you're getting consistent numbers.

* Full disclosure: I'm an idiot so take my advise for what it's worth.

Scott's a bright fellow and a good guy. I'm sure that's a reasonable suggestion for timing.

Here's a good video explaining you timing, retard and e85.


Tuning cells under boost for E85 seems worth it especially on mid range cells. Not sure if something could be achieve with consistent results on virtual dyno though. I'm not there yet with Miata but on my previous car (Evo VIII) tuning only for WOT vs. tuning also for mid range was a night and day difference in the way the car felt. It was way more responsive and brutal.

Hey thanks for the replys I'll be reading amd such about where to lay attention to and how to take advantage of e85 fueling and timing. I did do a virtual dyno plot on e85 last night with timing advanced about 3 degrees in boost 100kpa and above. I did a few pulls on the same road. At first I got more power about 20hp and tq but the other pulls only showed a marginal gain so maybe it's not that easy for me to just up some cells and go. I did notice however the car did feel faster in mid range much quicker actually. Anyhow I just wanted to run that little test to see. Oh I also forgot to mention that when I compared the test of 93 vs e85 my tank was almost full on e85 vs little over 1/4 tank on 93 I'm sure the extra weight may have been a factor.

But yeah from what I see it's not as easy to just add to cells and go. Looks like I'll have to take the car to the dyno to take full advantage of the fuel. Before that I think I want to step up a little more in boost/ convert to a 6 rib setup (supercharged, go easy on me lol). I'm currently topping out at 13psi above 6k rpm but the charger averages about 10psi from 2.2k till then. I think I can go up just a little bit and be safe on a stock engine. I don't push this car all the time and rarely go WOT on the street where it's driven.