Originally Posted by Ben

Why not go MS2 and a Flex Fuel sensor?

Originally Posted by Ben

You can get to MBT with a low comp BP and a 2560 on pump gas.

Originally Posted by webby459

You are saying 13 when read from a wbo2 gauge calibrated for gas, important distinction needing clarification if anyone reads this. More accurate would be to call this .884 lambda, or ~8.6:1 real afr of E85. In my research, .86 lambda is max power lean for E85, .71 for max power rich. So 13 on a gas wb02, .884 lambda is, if you believe what's written out there, a little lean.

I spoke with Emilio a little about E85, and actually wanted to talk to you about it since, because I knew you were using it. Good timing. Copy/pasted from an email I wrote to Emilio at that time regarding fueling:
Injector sizing, from RC Fuel Injection I used the injector worksheet at the bottom of the page. Interestingly, RC doesn't specify what fuel you are calculating for, so I assumed it was gas and made adjustments to the bhp field to account for the difference between e85/gas. 300whp X 1.15 (15% drivetrain loss) X 1.4 (a conservative 40% more req fuel for e85 vs gas) = 483bhp. Other contants: .65 BSFC, 80% duty cycle, 60 psig base fuel, 4 injectors=878 cc/min. BTW, I will probably be using a Bosch 1000cc, highly recommended by my tuner.

From this, bumping up the base fuel pressure to 75, a less conservative 30% more req fuel for e85, driving the duty cycle up a little, may get away with a 750 to make 300 wheel. I already have one set of too small injectors to find new homes for, I don't want that to happen again. Considering the 1000s are reported to idle well, I think this may be a reasonable choice.

Bellwilliam, I'd be very interested in what your base fuel pressure is, and what your injector duty cycles were at the big end of your 232whp dyno run on those 550s. And by the way, is your fuel consumption gross on the track.

Thanks for the input.

Originally Posted by bellwilliam

60psi FP. it was 90% DC on the dyno. but we've leaned it out since then. it was running a bit rich before, engine was running too cool (if there is such a thing) from E85 and Rotrex. funny thing was I accidentally loaded a gas fuel map, and other than puffed a lots of black smoke from running rich (high 10s), it made almost the same power (5whp lower) as leaner setup. I guess E85 just don't care.
I will test it to see what mpg is this weekend at Buttonwillow. I believe I was getting ~6mpg at AAA Speeway (don't have a working speedometer), a lots of WOT on that track. I am guessing around 7mpg elsewhere.

don't forget on E85, you are running ~1 point leaner.

I am sure you are right about the lambda. I am currently at 12, which is 0.816 lamda. hopefully that would be good. it is strange that 0.71 (10.44) lambda for max power rich, as it was making a ton of smoke at anything in low 11s (0.76) .I also have a lot of timing pulled (~15 at max peak tq). EGT peaked at 900F on the dyno, 1,200F at AAA Speedway.

I just did a dyno pull at Kraftwerks 2 days ago. it is now only 232whp. if I pull the restrictor out, add a bigger injector (750cc ?), it looks like it will go to ~280-290whp on that dyno (before it goes kaboom on my stock block).
KraftWerks Rotrex Race kit prototype on E85 - MX-5 Miata Forum

excuse me if I don't make some technical sense, I am just learning it all.

Originally Posted by I am Jack's NA

Wow, this thread is a wealth of information! I'm new to Miata's and this really helps my decision process on to turbo vs not to turbo.



If you are really serious about controlling your fuel delivery, talk to Tony at T1 about Racing Dynamics Bosch Injectors.

Fuel Injectors

You will not find a better performing and matched injector.

The 2200's are pretty huge, but you can run the 1000's at much higher base pressures than you may think. Tony told me that he has run them in 1000+ whp Supra's at 90psi base pressures. Obviously they are running giant fuel pumps, but you get the idea. The ID Bosch injectors love pressure.

Not sure if it was you that was talking about the Walbro 255, but skip it and go straight to a Bosch 044, especially when e85 comes in the mix. The Wally's have questionable resilience to e85 and the Bosch will out flow it and run higher pressures more reliably. It's better in every aspect.

You're peak timing under boost is insane, even with water/meth injection. You really need to dial it down and turn up the boost to compensate. You can make a lot of power safely with more boost and less timing. Timing kills motors much sooner than boost does.

Originally Posted by Ben

Take a look into the MS2 code, it is supposed to scale both fuel and spark with the concentration of alcohol. I haven't looked into it, as there is no known local source of E85 for me. BTW, there are numerous benefits to MS2 over 1. I don't want to skew the thread, but strongly suggest you look into it.

Why did you make a big deal out of low comp? Are you planning on something like an 11:1 turbo motor? Yeah you could do that with E85, but I still think the 2560 turbine is too small.

Originally Posted by 1slowna

a 10.5:1 comp bp with mentioned head work and some cams would have no trouble spooling a much much bigger turbo then a gt25 you could prolly get away with a 3071 and have no issues at all.
even with low compression i would think a gt2860rs would spool up instantly.