E85 flex fuel

[kazriel]

Hi guys,
Looking for some advice on how to set the car up for dynamic octane fueling.
There's a pump relatively closeby that sells E85 and continue to hear the benefits.

Would like to start E30 and taper up to E85 if the car can handle it. Ideally however would like the car to automatically adjust to the fuel mixture it's running. IE 98 octane -> 105 depending on what I fill up with without me having to manually select the right tune.

To do this I believe I would need to install a flex fuel sensor and am planning on getting a Fuel-It stage 2 LPFP. I've got a newer OEM HPFP being installed on Monday which is mainly due to the old one passing away.

I'm running DCI, JB4, 5" stepped intercooler and catless DPs. From what I read the Jb4 on map 5 will not be ideal to automatically adapt to variable ethanol content but am unsure how to proceed from here?

With the flex fuel sensor and the right software I would assume that parameters could be set for the optimal tune depending on the fuel mixture but am unsure what software/hardware module to communicate with the flex sensor is best to go for to achieve this?

Anyone one running E85 mixtures or pure E85 have any tips on how you're doing this? Did you install a flex fuel sensor to automatically adjust or do you set it manually depending on what gas you load up with?

[OzJustin]

I'm keen to hear about the flex fuel sensors too. A set and forget setup would be very beneficial. Will read with interest.

[flinchy]

The Jb4 flex fuel is still in development AFAIK.

plus, when it's done, you'll need port injection with a return line, as the sensor needs fuel flowing through it to read the E%.. and if it was on the feed line, it'd just be a restriction.

And yes it's set up manually. 98 RON baseline tune, E85 full power tune, then the flex sensor sends the E% to the ECU/piggy, which then varies whatever values it has access to, to remain safe.

[BMWhoarder]

as of right now you cant dynamically adjust. Scalars need modification in the flash to run higher concentrations of ethanol that the JB4 doesnt have the capability to influence.

[martymil]

Its coming soon, I've heard.

[MR RIZK]

Originally Posted by flinchy

.. and if it was on the feed line, it'd just be a restriction.

In theory it will pose a restriction and slight pressure drop however I don't believe it has been quantified at what point it becomes a restriction. ie: at what HP levels it becomes a concern. I know most will opt for the sensor on the return line but as mentioned depends on your goals.

Below is a quick blog from another site:

LINK

[martymil]

He flex sensor is not a restriction as it's slightly bigger than the original fuel line

I've been running it on the feed line without a return line and making over 400 rwk with no pressure drop what so ever

Until you see a pressure drop on the lpfp stage 3 there is no real concern at this point