Running ethanol in E24

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GazM3
Posts: 1791
Joined: Wed Oct 26, 2011 12:55 pm
Location: Melbourne, Australia

Running ethanol in E24

Post by GazM3 »

Hey chaps.
Unfortunatey my m635csi fuel system is running very rich accross the board (af 10’s at wot and 12’s at cruise) . I can’t alter the air meter tension enough to make it work and my fuel adjustment computer has been stolen by my e34. Had a brainwave that the air/fuel ratios would be perfect for a 50/50 blend of Ron98 and e85. Filled up with the mix and the car runs beatifully on it. Prob better than it’s ever run before.

It may only be a short term thing but are there any pitfalls from running the e85 blend (effectively e40) ?
BMW’s
84 E24 M635csi
90 E34 M5 3.6
94 E34 540i/6 SC E85
97 E36 M3 euro SC U/C
97 Z3 2.8 widebody

OTHERS
11 Audi S5 3.0 SC
19 VW Amarok V6
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Brucey
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6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: Running ethanol in E24

Post by Brucey »

the alcohol burns OK reacts with some materials and it also (usually) means more water in the fuel . Might cause big problems, might not. Folk over here are worried by 1-2% ethanol increase in ordinary unleaded.

BTW you could solve the problem by fitting an adjustable FPR, could you not?

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GazM3
Posts: 1791
Joined: Wed Oct 26, 2011 12:55 pm
Location: Melbourne, Australia

Re: Running ethanol in E24

Post by GazM3 »

Thanks Brucie. Yes the adjustable FPR is the other solution. It’s only a temp measure as I’m building an e34 loom for a haltech ecu. An adjustable fpr may be useful for tuning etc in any case.

As the fuel tank is mainly a closed system the issue of excessive water absorption may not be so bad in dry climates like here in Australia. In the uk with the extra moisture in the air this may be more of a problem especially if the car sits around. The steel fuel tank may be a concern tho.

It seems to run really nice on the blend. Cooling the intake charge is a nice side benifit. I’ll look into it further.
BMW’s
84 E24 M635csi
90 E34 M5 3.6
94 E34 540i/6 SC E85
97 E36 M3 euro SC U/C
97 Z3 2.8 widebody

OTHERS
11 Audi S5 3.0 SC
19 VW Amarok V6
User avatar
raykoke
Posts: 121
Joined: Sun Mar 02, 2014 11:18 am
Location: Savannah GA USA

Re: Running ethanol in E24

Post by raykoke »

I think there is a fuel quality switch position which may help.

Cheers,

Ray
'85 ///M635
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