[punchitchewie]

So for a noob here, it looks like from whats been posted, E85 on a stock n54 will provide no benefit? Is that correct? I would have to have an aftermarket tune to get any benefit (hp related)?

[JStang]

Originally Posted by punchitchewie

So for a noob here, it looks like from whats been posted, E85 on a stock n54 will provide no benefit? Is that correct? I would have to have an aftermarket tune to get any benefit (hp related)?

Correct. It might clean up timing corrections but in terms of power you won't see gains without being tuned for it.

[VNeBLOB42]

Originally Posted by punchitchewie

So for a noob here, it looks like from whats been posted, E85 on a stock n54 will provide no benefit? Is that correct? I would have to have an aftermarket tune to get any benefit (hp related)?

Add a little may clean up some corrections, but not worth the hassle. N54 is designed to run on ACN 91, worst case. So if your running 93 wouldn't bother.

[punchitchewie]

Thanks for the responses. I have access to 93 pump and use that all the time.

[BMWM.D.]

Originally Posted by Ilma

Yup......finally got it - Thanks!

Lesson learned......know what your datalogs really mean.....the numbers are not always real.

Also keep in mind that some of the piggy tunes like to run these engines on the lean side. I recently put my N54 335i and a friend's N55 135i on the same dyno for a few back to back pulls. My car was running Cobb's E30 "race map" with the AP, and my friend's car was using the JB4 stage 2 (I think). Both cars were running ~30% ethanol. The wideband 02 on the dyno was calibrated for ACN pump gas. My car showed consistent ~12.0:1 AFR on all pulls. His JB4 car was in the 14's through most of the powerband, then went way fat up top. Different tuning methods produce different results. I much prefer the Cobb approach.

I'm not sure what the exact stoich value of E30 is, but I'm guessing it's in the mid-13's. Of course, when I'm logging at idle and cruise, my datalogs show mid-14's for AFR.


One of the great things about the N54 is it's closed-loop WOT fueling. While it doesn't know how much ethanol you have in the fuel (unless you add an aftermarket sensor/kit), it sees the need for more fuel being needed to meet it's lambda targets, and can correct via the fuel trims. Obviously, this shouldn't be used as a Band-Aid for proper tuning, but it can compensate for variations in ethanol % from tank to tank.