[raannathr333]

Came across a few articles on blending E85 & 91 octane as well as the below calculator. Given I’m in CA; it’s either 91 or 100 race fuel at $10+ a gallon.

Or, blending E85 & 91.

Blended 4.5 Gallons of E85 & 16.5 gallons of 91; for a blended octane of 94.1 Octane or E27.

In the future, I intend to blend 5.5 Gallons of E85 & 15.5 91 for a blended octane of 94.7 or E30.

Cheaper way to improve power and mileage? So far, was able to run Map 7 (suggests 93octane +) with no issues, knock, rough idle, etc.

Thoughts?

Mix Calculator

[cobramite]

Sounds good.
It would be interesting to log a run up to redline on map 7 with the 91 based E30 and see how the timing holds up.
I intend to go with a higher octane here in FL based on the available 93 when I get some more miles and install a JB4 on an M60i. Burger's tuning dynos show huge gains on E30 with map 6.

[slicky]

I did that in our tuned twin turbo explorer. It allowed it to run a more agressive map without as much knock. There was no ethanol sensor so the only benefit was not pulling timing on the existing tune. The car had no idea how much ethanol it was getting. It was a bit of a pain in the ass as it was a rough guess how much you are blending in. It did the trick though.

[raannathr333]

Originally Posted by slicky

I did that in our tuned twin turbo explorer. It allowed it to run a more agressive map without as much knock. There was no ethanol sensor so the only benefit was not pulling timing on the existing tune. The car had no idea how much ethanol it was getting. It was a bit of a pain in the ass as it was a rough guess how much you are blending in. It did the trick though.

How long did you run it like this? Was it a one-off or over a period of years? Trying to figure out if I’m stepping into the danger zone or this is within tolerances.

[cobramite]

Originally Posted by slicky

I did that in our tuned twin turbo explorer. It allowed it to run a more agressive map without as much knock. There was no ethanol sensor so the only benefit was not pulling timing on the existing tune. The car had no idea how much ethanol it was getting. It was a bit of a pain in the ass as it was a rough guess how much you are blending in. It did the trick though.

What tuner were you using?

[slicky]

Originally Posted by raannathr333

How long did you run it like this? Was it a one-off or over a period of years? Trying to figure out if I’m stepping into the danger zone or this is within tolerances.

I did it for years. It was a canned Livernois tune. Even with the 91 tune, running 93 octane I still couldn't get LOR multilplier to even -0.2 (for these that know what it is). With mixed in e85, I could get full -1. This means the fuel is able to support maximum timing for the tune.
I was mixing only about a gallon and a half of e85 per tank. It was probably e15 or so and was still enough.

If E85 wasn't immediately available, I just let it pull timimg and raise LOR until it finds the level that the gasoline could support. Then when I added e85, it would start adding timing again and lowering the LOR towards -1. So it was somewhat a natural process. Being able to monitor the LOR in the Torque app helped a ton. You are kind of blind without it. I have no idea if there is something like that for BMW. You dont want to add too much as besides just being corrosive and abrasive, more fuel is required with E85, so you might start seeing low fuel pressure at full throttle as the fuel system runs out of flow capacity. Livernois told me, people were getting low fuel pressure codes and fuel cuts at E18 and above, so the explorer's stock system didn't have much headroom.

[cobramite]

Todays knock sensors are quite sensitive which allows your ECM to make accurate decisions about which timing table to use, adding advance for better performance or retarding to protect the engine when lower octane fuel is detected(octane adjustment). -1 to my knowledge is maxed which allows the use of a more aggressive timing advance map.
Adding some e85 seems to work well in this effort which is obviously easier requiring less e85 per tank when you are using 93 vs 91 octane.

[eluded]

You can add 1-2 gal E to help with California 91. Anything more make sure you have tune that see's it. Not sure on my new G06 but on my F30, I run a flex fuel map with an ethanol sensor, works GREAT! The Gen1 B58 LOVES E30-50, any lower not worth it, any more and it doesn't produce any more power.

[raannathr333]

Originally Posted by eluded

You can add 1-2 gal E to help with California 91. Anything more make sure you have tune that see's it. Not sure on my new G06 but on my F30, I run a flex fuel map with an ethanol sensor, works GREAT! The Gen1 B58 LOVES E30-50, any lower not worth it, any more and it doesn't produce any more power.

Good looking out. I believe targeting E20 to E30 seems to be a sweet spot for power without diminishing returns. Anything slightly above 93 octane, and I’m comfortable that the car is operating within tolerances.