5.0/Boss - any reason we can't blend in some E85 to raise octane?

[KrisR]

I was thinking about this the other day. I have a 93 octane tune that I haven't used yet because I have not been impressed with the BP 93 gas that is sold in my area. I got quite a bit of KR even on my 91 tune using this fuel. I was thinking about adding some 100 unleaded for track days / weekend playing but then I thought about splashing in a few gallons of e85.

Our cars are always in closed loop, fuel trims are always maintaining commanded air/fuel ratio. As long as we keep fuel trims in a reasonable range, why couldn't I run some e85 in the tank to raise octane?

I figure even running 1/4 tank of it (4 gallons of E85, 12 gallons of 92 pump gas) should still keep fuel trims under 10%, which should be no problem. I have run E85 in my previous two F/I Mustangs so I know the upsides and downsides.

4 gallons of E85 and 12 gallons of 92 should produce around 95 octane and a cooler burn, and should change fuel trims around 8% by my calcs.

Not like we need to worry about running out of fuel system in our cars with a couple bolt-ons.

 

[myponyjose]

I have a friend with a supercharged Jaguar and he blends E85 with 91.

 

[KrisR]

Yep, forgot I posted this here. I've been doing this now since just after I posted the thread. Works mint. I keep the mixture around 20-25% E85 to 75-80% 91 or 92 pump gas and I see up to 3-4 degrees less KR than I was before and the car runs great. Even part throttle feels better. Fuel trims are typically +8-12%.

 

[04sleeper]

Nice info. Thanks for testing. :beer:

 

[KonaFifty]

are there no side effects in the long run?

 

[KrisR]

are there no side effects in the long run?

There shouldn't be. Most fuels (at least in my area) have some ethanol in them, approximately E10 (10% ethanol). This mix I've been running is more like E20-E25. People have been running straight E85 (with a tune of course) in their Coyotes for years now.

 

[KonaFifty]

There shouldn't be. Most fuels (at least in my area) have some ethanol in them, approximately E10 (10% ethanol). This mix I've been running is more like E20-E25. People have been running straight E85 (with a tune of course) in their Coyotes for years now.

Ya, I been following some of the threads, just wasnt sure it was good to run a blend without a proper tune or not. I probably will not run an e85 tune because I drive my car daily and drive it on trips, so dont want to be stranded in an area with no e85 lol.

 

[KrisR]

Ya, I been following some of the threads, just wasnt sure it was good to run a blend without a proper tune or not. I probably will not run an e85 tune because I drive my car daily and drive it on trips, so dont want to be stranded in an area with no e85 lol.

You can always have multiple tunes stored in your handheld programmer, you know. Maybe contact AED or Lund or whoever your tuner of choice is and get both an E85 and 91 tune sent to you, load both of them in and you'll be ready for whatever.