I've been contemplating playing with some E85 in my N/A BP4W next season especially after seeing the results the 949 guys are having on their NA8 motors. If you haven't seen the thread on m.net here it is;
[NA] 135whp with stock NA8 long block - MX-5 Miata Forum

The TL : DR, 135whp on a healthy NA8 with stock header, 137WHP on a not so healthy NA8 with a RB header. Both cars have a completely stock fuel system and injectors sans Megasquirt. My goal is to see where I can take my BP4W which is already making ~140whp on watered down CA 91 and share the information with everyone.

I've seen both sides where some say to replace rubber lines, injectors & fuel pumps and others who swear on replacing everything. One consistent piece of information I have found is that replacing your fuel filter after a few tanks is critical to prevent it from being clogged. Does anyone with experience in long term use of E85 want to chime in with anything they have learned?

A major discrepancy I've noticed is the methodology for changing your fuel map. Some folks use their existing VE map, multiply by 1.3 and from there the information seems to get muddy. Other's change the req fuel number to increase everything and fine tune from there. I do understand that all my enrichments and cranking information will need to be changed as well. What is the recommended best practice for setting the map up for E85?

 

I like it. Use it on all my fun cars now.
You absoulutely do have to upgrade the injectors though.
I haven't replaced the filter before and had no issues whatsoever, but from what I've seen and heard, its probably a good idea, even more so on a high mile/older car. Its so cheap and easy too, why not.
I've used both strategies - the latter works best. Bump req fuel by 30%, then fine tune.

Both my 00 and my current 01 love the stuff.

 

You feel the 260cc NB injectors won't flow enough for an N/A application? I have a new fuel filter laying around, I'll probably swap it after a few tanks since I am on my original one.

I was leaning towards the req fuel, thanks for the info. I am excited that I found out that my local E85 station has a year round 83% blend so I will not have to deal with the seasonal blends I've heard about.

 

You know what, I guess I'm wrong on the injectors. Reading that thread now, and apparently the stockers have enough headroom for e85. I'm very surprised, but if Emilio did it on more than 1 engine, then I guess it works.

I guess I under-estimate how little fuel these engines need when properly tuned ( ie: not going pig rich in open loop)

Yeah this stuff is great. I haven't ran into knock yet, and I've tried some really interesting things with my timing and vvt maps lol

 

The fact he was successful with multiple vehicles is what inspired me to want try it. If there was any form of boost involved, different injectors would be put on without question. I'll log the duty cycle and post it up once I fill it with E85. How much timing were you able to get away with? I know on my current 91 tune I maxed out around ~31 up top.

 

I haven't pushed it on this 2001 setup, but its at 36 now up top. Doens't feel any faster if I keep going, so I stopped. No real dyno testing though, just a virtual dyno plot. Feels a whole lot quicker than stock though, that's for sure.

With your lower compression, you can probably push it even more.

 

Hmm interesting, I am interested to be able to quantify all these gains. I also plan on doing one last dyno with 91 before to have a starting point(I'll be using the same dyno for each test). For science this is my current 91 map.

 

No need to replace all the lines. You may need to do the fuel filter, all depends on how much gunk accumulated in your tank over time. Mine is pretty clean inside.

You should either change the ecu's stoich value if that is an option, if not, change the injector scaling by 30% (believe this is called required fuel in MS).

 

Not too long ago Grassroots did an article where they dyno tested an N/A, NA Miata, running MS with a bunch of different fuels, including E85.
The E85 made some significant power. This isnt news, but since some MTnet users have a phobia of theory; there is the hard data as tested on a Miata.

 

I've been under the impression since I use an AEM Uego I shouldn't change the ECU's stoic value as the AEM will automatically convert the lamba signal to a gasoline equivalent.

I didn't know they did an article on it! I'll have to find it and give it a read.

 

Your wideband just sends a voltage to the ecu, the ecu interprets it as some lambda value. It needs the stoich value in the fueling calculations. I believe the stoich value, injector size, and engine displacement are all wrapped up into 1 variable on the MS, required fuel. In some ecu's they all have their own value since they are their own constants in the VE fueling equations.

 

Yes those are the variables for the req fuel, however, I think I may misunderstand what the wideband is doing. Everything I've heard, so far, has said you simply up your req fuel number by 30% without touching the stoich # as the AEM is not programmable for E85 and the controller outputs as if it's gasoline no matter what. I'll look more into what other folks are doing.

I dig a little digging and someone on a BMW forum(BMW M3 Forum (E90 E92) - View Single Post - Compared: 87 E10, 93 E10, 93, 100, 105, E85 and M1) posted the results;

 

If the required fuel has all that, then thats the value you change. The displayed stoich value in the tables is just that, something tuner stupidio uses as a conversion factor between the stored lambda data and what it displaces on the screen.

 

Im currently piecing together parts for my e85 conversion on my CSP car, I got some 440cc rc engineering injectors, and now im thinking about the fuel pump. Do you guys think a Aeromotive 340LP would be a little over kill?

 

Yes, stock should be sufficient, wally 190lp if you're feeling frisky.

 

for n/a there's really no need for more than the 190

 

I had a Walbro 190, and it died after 6 months. Walbro told me that it was my fault and wouldnt warranty it. They claimed without even looking at it that I had contaminated fuel. So I pulled the sending unit, tank was perfectly clean. Cut the fuel filter in half, no dirt at all. So **** Walbro, not buying from them anymore. You really think stock is sufficient enough to flow enough e85 for racing application? Even though its n/a.

 

Yes it is. You can either stay with the stocker or get the DW65 or DW200 if you really want to upgrade. Anything more might be a bit rough on your stock fpr and/or might overwhelm it

 

Well I was planning on upgrading fpr as well. Obviously im not going for high hp here (shooting for 160 at the wheels) but im just trying to build a free flowing system with no restrictions so I dont have fuel pressure loss at high rpm. Im going to build my own dual feed rail with a nice external fpr.

 

Sounds like a whole bunch of un-needed extra weight.