E85 Conversion

[bost857]

I am getting ready to install my MS-II with a custom wiring harness and a relay board. Any ways I have been toying with converting my 1988 5.0 mustang to run on E85, the engine is pretty stock at the moment. I want to know if I need any other modifications done to the engine besides bigger injectors to convert?

[.boB]

I've been doing a lot of research, becaue I'm planning on doing the same thing. Every once in a while, I want to use E85 on the street. And I want to use it all the time at the track.

There are a couple of small issues that need to be addressed. The first, of course, is the need for 25-30% more fuel volume. You'll need bigger injecters and a bigger fuel pump. Not a big deal, easily done with off the shelf parts. But if you're upping the power output with something like a blower, you also need to upgrade the entire fuel system.

There is concern that Ethanol will eat rubber parts. That doesn't seem to be the case. It's a good theory that hasn't been proven. I left a piece fuel line in a bottle of E85 for about a month. Didn't seem to affect it any.

The final thing is the tune. That's where it gets tricky. E85 is not really E85. At best it's E81, and can be as low as E70. That can effect the tune quite a bit. Factory flex fuel vehicles use a fuel composition sensor. But that is probalmatic. They are very expensive - $300-900. They are not durable. Accuracy is suspect. And they don't have big enough lines for performance use.

My plan is to program the MSII with 2 tunes; one for straight pump gas, and one for E70. And then use an external switch to manually change maps as I need to. On the rare occasion that I want to use E85 straight from the pump, I'll let the tank get pretty low, fill up, then hit the switch. Matt believes it will work.

[TouringBubble]

I run E85 in the Evo and only had to update the injectors and fuel pump.

The issue IS the rubber components ... but only older rubber components and specific rubber/plastic compounds. For instance, on the Evi VIII and IX you can run E85 on the stock lines. But, on the newer Evo X they replaced the lines in the fuel pump assembly with a clear plastic line, which does break down in the ethanol fuel. Replace these 2 small lines and you're good in this case.

Fuel lines in about any car from the last 15 years or so should be fine, as long as they are the standard reinforced rubber lines ... the same generic stuff you can buy at the local parts store. Most stock EFI cars will have these. Older fuel lines could have a different rubber compound that could break down or harden in the ethanol. If the car was carbed, it would definitely need new lines. Also, as in the case of the Evo X above, any uncommon lines used could be an issue. Metal lines should be fine.

Also, some natural fiber "socks" and such on fuel pumps and some fuel filters could break down in ethanol. Most synthetics, metals and hard plastics are fine.

One thing to note is that E85 WILL clean out the gunk built up in the system over time. Plan to change the fuel filter pretty soon after you change over ... maybe twice.

I'm planning to run E85 in my Beetle MS project and will be changing all of the fuel lines. They are 40 years old and made for low pressure, so I have to change them for any EFI application ... but they would break down in ethanol if I stayed carbed.

As for tuning, I've found that the difference between the E85 mixes doesn't affect my tune much. We don't get the grade 3 here (E70 min) ... we only get grade 1 and 2 (I think E76 min). I tuned the car for the summer grade 1 blend and have not had issues in the winter. But, I'm no where near the knock threshold of even the low grade. If you tune for MBT and then add a degree or so of safety margin to the tune, you should be fine, even on E70.

[crossramhemi]

Will the O2 sensor automatically adjust the system to run E85 or will the ratio have to be manually changed by the operator? I know that on my Flex Fuel van it is automatic.