A few weeks ago, I took my truck to the dyno I normally test on. Did 3 pulls on 93, added some pump E. Only saw 40% on HPT, still managed to consistently pick up 7rwhp & 7rwtq. Have not had a chance to get track results. I need to get my logs to the tuner that helped me with the flex fuel tune. Timing seems high, but no knock detected. Plugs show zero signs of detonation.

 

It’s a waste of time unless you can get the % up to at least 70%. I added some true E85 from a 55 gallon drum to mine and picked up 60 rwhp. That was on a 75% E mix with 105 octane. At a 65% mix it was only 25 rwhp and that was mostly from the cooling effect that allowed for more timing. With boost it helps a lot, NA not so much.

 

I am mainly doing it for track days, hoping there's about a .1 advantage over regular 93. This engine is about 10.5:1, my new engine will be over 11:1 compression.

 

If you can get the mix over 72% you should pick up 20 plus rwhp. I swear less than 60% puts you down or on equal power as good 93. Try adding some race gas 100+ octane to your 93 and make a witches brew. NA you don’t need the cooling, your after the octane boost.

 

Even with a naturally aspirated engine? I had several people tell me that I likely gained the majority of the power on 40%, and would see maybe 1-2 more at 60-70%.

 

They are wrong, most power from E85 comes from a mix greater than 70%. You will get a cooling effect that helps make power but to get the real gains you need the extra octane from E85.

 

I agree.
It seems 70-75% is the sweet spot. Higher the better but 10-60% just doesnt seem to help much at all.