Turbo M42 E85 Conversion

[sonomaGTLN2]

Hi all - been a while since I posted on here, but I decided late last year to convert my turbo M42 to E85. Upgraded to 80lb injectors, 340LPH fuel pump and replaced my leaky .48a/r godspeed turbo from 2012 with a .60a/r turbine/.50 compressor ceramic ball bearing turbo. Also ditched the motronic L-Jet for MS2 housed in a KDFi ECU.

Got it idling good and running nicely on Octane 93. E85 runs well up to about 10 PSI (my target is 15), then fuel pressure drops and I’m not able to get lambda below .84. Has anyone done an E85 conversion of their own on any car? I am using the stock fuel lines and I’m beginning to wonder if I need to go with bigger lines all around. Is 5/16” too small? Also wondering if going to semi sequential vs batch fire injection would help smooth/maintain fuel pressure. Any thoughts?

[pofo]

You need to swap all your fuel lines to E85 safe same with your fuel pump and O rings, E85 will eat right threw them. If you have not done so al ready.
How are you tuning the car for e85? Do you have a flex fuel sensor?

[sonomaGTLN2]

Fuel pump & Injectors are good for it...Given the fuel starvation issue I'm probably just going to update to 5/16" lines across the board and I might as well confirm they are good for E85 (I replaced and bent generic lines when I did the M42 swap in 2008, but I don't recall if it was 1/4" or 5/16" and whether they were E85 rated). Been using a GM FF sensor on it that has 5/16" line and have been tuning in MS2 for about 6 months (current ethanol content is 70%). Got it to run good on Octane 93 first then switched over to FF and have been tuning VE3 maps without ethanol percentage compensation.

[pofo]

I really like High Performance Academy on youtube. They do a good job and you can buy videos on what your trying to do.

Here is a sample on there normal channel

https://www.youtube.com/watch?v=RTzW4V3t7JY

[hotdish]

I think powerkraut has posted an e85 turbo m50(?) e21 build on the forced induction subforum. You'll probably get better answers there, if you haven't posted already.

[sonomaGTLN2]

Hey all - figured I'd post a thread for posterity sake as I'd say my E85 conversion is complete!

I upgraded my fuel line to 1/2" aluminum late last summer and was finally able to get lambdas down where I wanted them under boost. Then (even after draining and replacing E85 with E0 Rec gas) over the winter, my in tank pump froze up and that was it...no early spring driving for the E21!

So I took the opportunity to ditch the stock fuel tanks and start from scratch. The passenger side would leak when full anyways. I went with the 12 gallon ATL well cell and a dual pump setup with an external swirl tank.

Deatschwerks DWMicro lift pump for internal tank.


Running to a Deatschwerks E85 Bosch 044 form external pump in a surge tank.




- - - Updated - - -

So of course before driving and tuning it with E85 my stock M42 clutch had its share of auto crosses and hard driving and I upgraded to a 7lb lightweight M42/M20 hybrid flywheel from Racehead in Australia. This allowed me to keep the M42 starter and go with a larger and more capable M20 clutch. Clutch and pressure plate are a SPEC Stage 2 M20 clutch.





- - - Updated - - -

And Dyno results after everything was together!

https://www.bimmerforums.com/forum/s...1GNtbObgA0HUDg