[Saberscar223]

I’m running the Flex fuel kit and most places by me are E70 and E85 is about 30min away. Is it worth getting actual E85 or is E70 fine?

[s346k]

what's the setup?

the only thing id consider is fuel quality. the na bolt on car i had ran the same on e65 or e83, didn't matter.

[arpad_m]

Although I haven't seen back to back dyno sheets from the same car using fuels with different ethanol contents, but based on several tuner's comments, diminishing returns start kicking in after 50-55% ethanol and almost all the extra power to be had is attained already at 70%. Increasing octane level no longer helps much beyond a certain point.

I'd just keep pumping E70 and enjoy 99% of the car's max performance, not worrying about E85.

[s346k]

there is a lot to consider with ethanol ratings. i used e85 all summer long and rarely saw over 80% ethanol content. it mostly hovered around 75. there is also a seasonal dependent minimum ethanol content schedule based on region. most pumps operate on the minimum or close to it. speedway & meijer (around here) offered the highest content. thorntons was among the worst.

i monitored mine via hptuners & a factory gm ethanol content sensor.

[Megahurtz]

E70 is plenty for a street car and you can throw a lot of timing at it. At a certain point, you wont go any faster E60 vs E70 vs E85 vs E90(ignite).

I would bet that you can put max timing into the car by E70 and you wont go any faster on E85. I actually change most of the cars I tune for E to have max timing by E70 instead of E80.

[Joshinator99]

Originally Posted by arpad_m

Although I haven't seen back to back dyno sheets from the same car using fuels with different ethanol contents, but based on several tuner's comments, diminishing returns start kicking in after 50-55% ethanol and almost all the extra power to be had is attained already at 70%. Increasing octane level no longer helps much beyond a certain point.

I'd just keep pumping E70 and enjoy 99% of the car's max performance, not worrying about E85.

Originally Posted by Megahurtz

E70 is plenty for a street car and you can throw a lot of timing at it. At a certain point, you wont go any faster E60 vs E70 vs E85 vs E90(ignite).

I would bet that you can put max timing into the car by E70 and you wont go any faster on E85. I actually change most of the cars I tune for E to have max timing by E70 instead of E80.

Agree with these guys. My max timing is in by E55 with no problems…seem to be making OK power lol.

[WiggyB]

Some say that the car seems to run better with some sort of mixture. I have 2 people I meet up with that say even though they can go full E they get better response and gas mileage doing some sort of mix.

[sr71bb]

Originally Posted by Saberscar223

I’m running the Flex fuel kit and most places by me are E70 and E85 is about 30min away. Is it worth getting actual E85 or is E70 fine?

With the flex fuel setup, normally your max values for timing occurr around the E70 level. Below that E70 level is where you start to see some potential GRADUAL loss of power.

E85 at the pump is rarely true E85. I have an AEROSPACE gauge and the E85 I buy at the pump (KROGER) is REALLY about E78.

NOTE: More timing doesnt necessarily make you go any faster. Typically tuners will give a car more timing until the car DOESNT make any more additional power then they back off usually 1-2 degrees.