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Effects of >91 octane fuel?

7K views 12 replies 10 participants last post by  Em3 
#1 ·
Hey there,

fact:
recommended fuel for the 2011 GT is 91 octane

problem:
a lot of gas stations here in germany won´t offer 91 octane fuel in the future. Minimum octane over here will be 95 (followed by 98 and even 100).

As long as is don´t screw up the engine with higher octane fuel, it´s ok. Does it have any effect on gas mileage, performance etc. ? Of course there´s also an economic issue about it, since gas price for 95 octane fuel is up to 6.50 $ a gallon in germany. :mad:
 
#2 ·
At this point I'm going to say that it shouldn't affect the engine all that much. If you can get the chip tuined to take the 95 octaine, you'll get more HP and better gas milage out of the machine. Other than that, I'm personally not going to be able ot tell you more.
 
#3 ·
Europe calculates octane differently than the US. The US averages the Research Octane Number (RON) and the Motor Octane Number (MON) R+M/2. Europe just uses the RON.

96 octane in Europe equals around 92 in the US.

Octane Explained
 
#12 ·
I think Ford recommends 91 octane so they can quote a higher HP rating, over 400.
If they recommended 87 it would have less HP, probably just below 400.
But the car will run fine on it. I will throw in premium though.
 
#8 ·
the 2011 mustang gt has adaptive spark advance timing allowing the engine to increase horsepower output relative to the higher octane.if you use 93 octane(usa) you should see a small increase over 91 octane.equipt your car with a ford racing air filter and you shoulld also see a small increase with the less restrictive air flow.over 93 octane shoold need a tune to get maximum horsepower ou.tput
 
#9 ·
hp-guy, so just dumping in some race fuel wont get more power than the 93?
 
#10 ·
Big mis-conception is that higher octane = more power. The higher octane rating basically means the fuel is less combustible. ITs needed in engines with high compression ratios to avoid pre-ignition (which hurts performance).

Here is a clip from wikipedia that explains it well:
Octane rating - Wikipedia, the free encyclopedia
Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.
 
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