Ford Focus Forum, Ford Focus ST Forum, Ford Focus RS Forum - View Single Post - What octane fuel to use?
View Single Post
Old 10-31-2012, 09:39 AM   #16
Fan4Focus
Focus Jr. Enthusiast
 
Join Date: Sep 2012
Fan#: 104234
Location: smalltown, MN
What I Drive: 2001 White ZX3

Posts: 35
Points 126, Level 2
Points: 126, Level: 2 Points: 126, Level: 2 Points: 126, Level: 2
Level Up 52% Completed
Level up: 52% Level up: 52% Level up: 52%
Forum Activity 0%
Activity: 0% Activity: 0% Activity: 0%
FF Reputation: 1 Fan4Focus Good Standing Member
Buy-Sell-Trade Rating: (0)
E85

Quote:
Originally Posted by Magus2727 View Post
I always thought that E85 was a less energy dense fuel. It does have a higher octane rating and it does have lower tail pipe emissions. but what benefit would you have? most regular fuels can have up to 10% ethanol anyway (I think recent law passed that made it so if its under 10% they did not need to advertise that it had that % in it...)

So your raising the octane of the fuel in your tank but your also lowering the energy density also. you may see a small drop in MPG. I think most flex fuel vehicles get a way with a slightly higher compression (due to E85 having a higher octane rating) to make up in their power.

I think a report showed that the Escalade vs the E85 and the normal one had a 1-2 MPG difference in its fuel economy. but E85 is sometimes cheaper and has less of a carbon footprint.
It is true that E85 is lower in heat energy. However, in higher compression engines (the Ztec is 9.6:1) you see a slight gain in performance with a blend such as 20%. If you go much over 20% you will start to see a loss. I have found 30% to be the turning point. When the Indy Racing League switched to Ethanol in 2007, they saw better performance on Ethanol by simply running higher compression ratios in their engines. They are running "denatured" ethanol (98% ethanol/2% gasoline). The E85 atomizes faster and therefore provides a cooler fuel/air mixture which actually boosts performance. Racers know that cooler fuel/air mixture provides more power. That's why drag racers use a "cool can" to lower the fuel temp. It is also why we put on cold air induction systems.

I am speaking to non-flex fuel vehicles here. Flex fuel vehicles have a different chip in the computer that allows for a wider fuel/air adjustment.
__________________
Fan4Focus

Last edited by Fan4Focus; 10-31-2012 at 09:44 AM. Reason: Additional info
Fan4Focus is offline  
    Reply With Quote