E85 Conversion for 1.6 non-turbo racecar - Miata Turbo Forum - Boost cars, acquire cats.

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Old 09-07-2017, 06:15 PM   #1
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Default E85 Conversion for 1.6 non-turbo racecar

I've been reading about E85 conversions everywhere I can, and there is a ton of useful information here - so thank you in advance. However, I'm looking to convert an N/A car, so I could use a little bit of getting started clarity.

Background:
We've had our 1.6 racecar on a 122WHP 93 octane tune on a MSPNP all year. Right not, I'm a little heavy or a little under-powered. It's been great though and I love it. However, if I can get another 5 HP on an E85 tune by squeezing some more timing advance out - I will be perfectly on my PW./WT ratio for the class we race in. I've read some of the work emilio did in his N/A E85 thread. I've read 2.4million E85 boosted threads. I've read about 100k E85 1.6 boosted threads. I feel like I have an understanding on the lamda vs. 14.6 A/F struggle. I understand the principles of more fuel to compensate. I get that cooler combustion and advanced timing is the magic of E85. But I can't find a good place to start for a non-turbo 1.6 E85 conversion. I'll stop here, and PLEASE feel free to link me to the holy grail thread I've missed.

Plan:
This weekend I've paid for a track weekend that is a throw away weekend since the championship points are decided. The car is not street legal, so outside of a dyno-renting this is a rare weekend for us. It's the perfect time to start playing with the E85 map, but I'm grasping at straws for where to start. I've read several suggestions for ~30% more fuel and 5' timing advance, but they are all boosted cars. Is it safe to start in the same spot on an N/A car, or should I start with my 93 octane base map? We only have 10 runs this weekend, so I'd like to get as aggressive as safely possible right out of the box, then make tweaks as we go. Since I'm N/A, I'm assuming I can start with more timing and fueling pretty safely - but I'd love some feedback.

TLDR: Where to start with timing/fueling maps for non-turbo 1.6 E85 conversion.
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Old 09-07-2017, 06:22 PM   #2
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What MS do you have? the 1 or the 2?
Updating REQ-Fuel is usually #1.
Then shaping your ve table such that it's like-stock everywhere and at least 12.5AFR at wot.
Then you probably want to start with oem-ish timing values of high 20's low 30's and go from there.
Can't really do much with timing unless you have some way of measuring the gains, because it's pointless and stupid to just blindly throw 5* at it if it's not making more power that way.
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Old 09-08-2017, 11:28 AM   #3
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I'm running full E85 on my 91 1.6L non-turbo. I certainly think I picked up some jam and it just runs smoother in general.

Here's what I was told about the AFR's: Yes, technically the stioc values are completely different. But your AFR gauge is reading in gas AFR. Just don't overthink it, keep it like this. No changes needed.

Here's what you do: Drain fuel tank (there's a drain plug on the bottom). Fill up with Full E85. Prime fuel system. Go into megasquirt, change the req fuel by around ~35-40%. Start up. Adjust AFR manually to get smooth idle. Run autotune for rest of map. Bump timing up -> Have fun.
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Old 09-12-2017, 01:51 PM   #4
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Thanks guys. ECU is a PNP3. Thanks for the shaping instructions, that's helpful.

Took 18PSI's advice this weekend and will wait for a dyno. We got to the podium this weekend so it's all good - could have had P1 if I switched to E85 sooner and squeezed out a few more HP..

Good to meet/read someone else who is N/A running E85 on a 1.6! It seems like you did the same approach as I am planning - so I'll keep that going for the 2018 build. Thank you for chiming in!
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Old 09-12-2017, 02:14 PM   #5
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The dyno will be the best tool, unless others chime in with a well tuned N/A E85 map. Although if you copy someone else's well tuned table, it may not be ideal for your car/conditions/etc. My point is that tuning E85 NA is different than the general rules for tuning in boost.

The goal is to tune for peak cylinder pressure at the optimal time that causes peak power without knock, regardless of fuel being used. E85 has a faster burn rate than E0-E10, which means that for the same ignition advance, E85 will actually cause the cylinder to reach it's peak sooner (more advanced) than gasoline. If your current naturally aspirated map is already tuned aggressively for MBT, then it may actually be necessary to retard spark by a few degrees to reach the E85 MBT. If it's safely tuned to stay away from knock, then it may need more advance to reach MBT. The reason that 3-5 degrees is a common number to advanced a boost map is because all the base maps out there for gasoline are tuned to prevent knock. E85 can take advantage of running closer to MBT since it is much more knock resistant than gasoline. I haven't seen the discussion around here about what spark values are typical for 100 kpa on E85. For 93, around 39-32 is typical for the top row of the map and I would imagine that's not knock-limited, so E85 may actually be more like 28-30. If you have a way to get on a very flat smooth road (even if it's at the track) to run a virtual dyno log of spark values between 27 and 33, you should be able to get an idea of the ideal spark advance. The dyno will be best at this, but since you're already signed up for a track session this would be the cheap way. Is it a race or test & tune session? If it's just a test & tune or track day, it'd be easy to do 2 laps hitting redline down the back straight, pull in the hot pits and change the top row, and do it again until you've done the sweep. You'd have to make sure that ambient temperature, IAT's, CLT's, and such don't vary much between pulls.
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Old 09-13-2017, 09:22 AM   #6
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Thanks Ace! It is currently tuned pretty aggressive. I would not have assumed I might need to retard it, that's interesting. My plan was to utilize the back stretch, bring it in, adjust, back stretch, bring it in, adjust - so it sounds like we are on the right path there. Thanks all, very useful info in this thread!
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