How much does ethanol gas effect your tunes?

C

COBESGT

Member

Oct 19, 2004

231

0

16

Dubuque, Iowa

Jun 28, 2010

#1

• Jun 28, 2010

• #1

So I took the Mustang on a 450 mile trip yesterday and the place that stopped for gas only had ethanol gas, 89, 91, and 93 octane. I always run 91 non-ethanol gas in my car as I have the 91 octane tune. To be safe I used the 93 octane, figuring if the ethanol did any strange things I'd still have 2 points to spare and I'd still be safe. So, does anyone have any ideas of how ethanol effects tunes?

 

jpplaw

Member

Jan 14, 2009

185

3

18

Jun 28, 2010

#2

• Jun 28, 2010

• #2

Chandler at Brenspeed told me once that their tunes normally take the 10% ethanol fuel into account. I have also heard that ethanol lowers octane and leans out the mixture. I used to race at a track that had a supermodified class and they ran super-rich on methanol.

Not sure if the octane numbers on the gas pumps are pre or post ethanol addition though.

 

DarkFireGT

Playing with my wife's really makes me want one.

10 Year Member

May 23, 2004

692

10

89

East Moline, IL

Jun 28, 2010

#3

• Jun 28, 2010

• #3

Doesn't change it enough to harm it. And Brenspeed, being in the heartland, definitely takes that into consideration. You do not need to run a higher octane. The difference in MPG is also usually less than 1 MPG.

 

S

ski

Member

Dec 14, 2004

380

2

18

Jun 29, 2010

#4

• Jun 29, 2010

• #4

Pure ethanol has an octane rating of 113, and less BTU/gallon than pure gasoline. E10(10% ethanol) fuel has the octane rating that's posted at the pump. E10 fuel reduces mpg.
(Note: Ethanol is prone to absorbing moisture, which will reduce the octane rating. So it's suggested to replace E10 with fresh fuel at least every 2-3 weeks.)