Benefits of E85 in a low-power M45 Setup
 

Hey guys,

So I'm gearing up to install my M45 supercharger and I'm thinking about different fueling and tuning options. The car will be M45 supercharged (No IC, Sebring Kit), MS3, RX-7 550cc injectors, Ebay Cat-back, 180 Degree Thermostat, and a professional Dyno tune unless by some miracle the logs look decent with a couple tweaks and autotune. I live in Detroit area Michigan so literally getting E85 is just as easy and convenient and pump gas.

So my question is is there any benefit to tuning for E85 versus pump gas? I'm shooting for 160'ish WHP. I do road courses and some AutoX.

Thanks in advance.

My thoughts are that the cooling benefits alone would be worth it even if the system is capped out power-wise without an intercooler.

More knock resistance, which will be especially handy with your lack of an intercooler (y u no intercool?).

yes

You should be able to make an extra ~15whp and be safer as far as detonation. I've been logging my gas mileage and 1000 miles into switching to E85 my gas mileage is down 17%. In my area E85 is running 32% cheaper than 93, so it's actually been cheaper overall to run E85.

Hahaha I'll be adding an IC eventually, but to start I'll be taking it in baby steps to take the stress off my bank account.

Makes sense. Our area is surrounded by E85 so it's no extra hassle expect for the extra tuning required. Is it safe to assume 550cc injectors will support a 160-170whp supercharged E85 application? My math says it should be fine and under a 90% duty cycle.

550cc should be enough. With E85 I would suspect you can run timing in the ~20s and not give any fucks about knock.. even with the ridiculous IATs from the M45. With a 1.8, 160whp should be easy mode. 1.6, still definitely doable, but may depend on if you have a pulley or not.

Figured it would be. It's a stock pulley setup, but I do have this: Miata Cold Air Intake for Jackson Racing Superchargers by DDMWorks Which could help a bit. Yeah if anything, the knock protection alone seems worth it when learning how to tune.

Will be watching. I am taking a similar rout with my M45, but no E85 here.

I'll keep you updated. Just buying the odds and ends and getting the MS3 in here this week. If it works I'll swap the injectors and go E85 before the supercharger. If all is well after some tuning I'll throw the supercharger on.

My roommate, Zac, has a spark map from his 1.6 M45 E85 setup that was night and day from the 93 setup. It's not dyno tuned, but was a collaboration of "safe" E85 spark maps found around the site. His was through an air to water intercooler so he had a higher margin of safety, I was assuming his 11 lbs of boost and ~170-180hp with E85 and ~120 IAT's that he wasn't knock limited.

If you want more boost, he's got his setup for sale. You could trade pulleys with him for more boost, then he's selling the whole air to water setup, since he's going F20C swap.

I had an na with an m45, that thing burned my arm a couple times when wornking around the intake LOL i had a lot of fun with that car.p
Harold at Putman Park M45 supercharged 1990 Miata - YouTube

This interests me greatly.

Running Megasquirt?
 

I have a similar set up and am in the middle of re routing the cooling system...my JRSC (really Sebring) with the big boost pulley has been in since 1997. Besides eating belts and a snout rebuild, it has held up well...however, I am now considering a change. I suspect it has more potential since the "Sebring Boost Controller" and 8 degrees advance timing is a play safe system. My NA I believe has 203cc injectors (stock). I currently do have the JR AFR gauge and a vacuum indicator. Under boost, it does read rich, as it should--so perhaps the injectors are fine, but I am guessing its due to the open loop condition and the injectors likely nearly 90% at the brief time I run WOT under boost. If I did this in a stepped fashion, how far can I go with the stock ECU and the injector size? I suppose I should get the MS PNP, WB sensor and then determine what changes would benefit new injectors. Also with the PNP in place, are there simple filters that then mount to the Sebring elbow?.....

Hate to be the guy to resurrect an old thread, but if you went through with the e85 conversion I would be interested to hear the results. Have an na6 with jrsc and factory band aids. Was considering upgrading to megasquirt and maybe e85(with bigger injectors, fuel pump obviously) if the gains are worth it. Any input would be appreciated.

No worries. I did end up going full E85, but not on an M45 setup. I will also be doing it with a 2003 VVT engine and c30-84 Rotrex supercharger. The benefits (even NA) were absolutely worth it. The car runs smoother, cooler and felt like it had more midrange.

I don't have any data, but back to back sessions at my local track puts the car about 2-3 mph faster on the back straight when on E85 so I believe there's some power gain. The power you'll gain simply from having a real ECU will be huge, maybe not in numbers wise but in feel.

My suggestions:

-Buy a MS3
-Learn to tune on it
-Buy DW200 E85 fuel pump
-FF640cc Injectors
-Don't overthink the switch to E85. It really is more simple than I ever imagined.

Thanks for the quick reply. I appreciate the input. I'll definitely be looking into it more. I am hoping that the e85 will help with charge cooling enough to put some timing back in for more torque. My biggest concern is learning megasquirt on a supercharged engine, which I have heard can be difficult.

Download tunerstudio/megalogviewer, a basemap, and a megasquirt manual, read through the manual and play with the tune. If there's someone close by that can show you the basics of the software it can help a lot, but it's pretty intuitive and user friendly. The more time you spend with it, the easier and more comfortable you'll be with it.

People post up tunes and logs all the time with questions and issues they're having. You can grab those and look through the log in megalogviewer for the issues they're having and what settings may look like they need to be adjusted. You can do a lot of playing in the software before you've ever got a megasquirt that will make the the tuning process a lot easier.

The first step is lots of reading and lots of learning. Only after you understand what each parameter does, and how it affects the tune, should you actually start looking at tunes/logs and applying your knowledge.

Last thing you wanna do is start copying other maps settings not knowing what they do. For some silly reason people think it's faster/easier, when in fact, it just sets you back and lengthens the time it will take for you to learn.

I'm not suggesting you save some random dude's tune to use on your personal car. Just suggesting that you can use some random dude's maps/logs to familiarize yourself with the software and how parameters work before getting a megasquirt anywhere near your car.

Megalogviewer is awesome for letting you see exactly how, when, and in what quantity different parameters affect how a car runs. If you don't have the knowledge, or a megasquirt, then some random log is a nice opportunity to actually see what's going on and what to expect when you do take the leap.

Ok, so I'm finally going through with this, so I'll bring this thread back. Actually ended up ordering the parts that goingnowhere suggested purely through luck and research(i kind of forgot about this thread). So I have a ms3 being built, FF640 injectors, and a flex fuel sensor. My question is about fuel pumps. I see that the dw200 was suggested. Is that overkill for my application? Is there any downside to getting a pump that flows too much? Any help would be appreciated. I realize I probably can't use the stock pump, but would a 190lph be better for my setup than a 255lph?