[tlmustang92]

I'm about to pull the trigger on a Gryphon but I got a quick question. I'm got an 07 FX4 FFV. So far I know I'm going with the 87 performance and a tow tune, but how does the E85 tune compare to the 91 tune? I wouldn't run either all that often, but would like to have a little more fun once in awhile.

[88Racing]

Stick with a 91 perf tune.
The savings with e85 at the pump are lost in mileage going down the road.
JMHO

[tlmustang92]

I'm not really to concerned about savings since I would only use it every once in awhile when I'm out screwin around. Since the octane rating is supposed to be higher with E85 can you get more HP with it? Or is it pretty much equal HP wise to the 91 tune.

[JackandJanet]

Originally Posted by tlmustang92

I'm not really to concerned about savings since I would only use it every once in awhile when I'm out screwin around. Since the octane rating is supposed to be higher with E85 can you get more HP with it? Or is it pretty much equal HP wise to the 91 tune.

As I understand things, there is less energy per gallon in E85 compared to "ordinary gas" at any octane rating. The higher octane rating simply means it is less likely to ignite (early) in the compression stroke and it burns at a slower rate which allows you to advance the spark somewhat.

But, the ideal A/F ratio for E85 is a richer mixture than it is for ordinary gas. This means each cylinder charge contains more fuel volume than it would with gas. Does this translate to more energy per cylinder charge? I don't know, but I kind of doubt it.

- Jack

[Power Hungry]

The problem with running E85 is that the compression ratio in the engine doesn't change so you can't take advantage of the higher octane of E85. Sure, you can advance the timing a bit and that helps improve efficiency of the combustion and provides a little more power, but engines built specifically for E85 would notice a significant power increase from higher compression. The same goes for oxygenated fuels.

[tlmustang92]

Awesome, thanks for the replies. I'll go ahead and stick with the 91 tune. I just got my tax return money this morning so I'll probably be putting in my order this morning!!!

[jeffro]

I was wondering the same thing. I have an 07 Flex 5.4 with CAI and Cat back not true duel. I just got my grypon yesterday and Bill said to use the 87 Tow until my custom 87 Perf and 92 perf tunes get built. WoW I got that tune all tweaked out just the way I like it. I run 90-92 ans just advances the spark 1 degree. So here is my question what tune do I use if I run e-85? The Custom 87 perf or the 92 or canned tranny only?