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Discussion Starter #1
I've been reading through the forums about whether 91 or higher octane in a stock 2011 V6 makes a difference and a lot of people seem to think higher octane is better. I've tried 91 octane wihtout any ethanol and I can't tell any difference from 87 octane with ethanol. If 91 octane makes a difference, why does the owner's manual say to use 87 octane?

2011 Ford Mustang 3.7L V6 Engine - Muscle Mustangs & Fast Fords
 

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1. Because the V6 is marketed as an efficient, yet powerful car.

2. Higher octane does make a difference. This is fact. The additional power is not much, but decent.

3. Personally, I no longer experiencing knocking in lower RPMs (around 1100-1400) with 91 octane.
 

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I traveled 800 miles on a trip from Phila. to Nashville. In cruise control at 75 MPH I was getting 33-35 MPG with 91 octane. It seemed to work for me.
 

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Power is not much at all. But my car runs smoother and my
Mpg is better.
 

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I think that a tune is necessary to advance the timing so that you get the real benefit of using 91. Before getting the Bama Tunes/SCT tuner, I switched between 87 and 91 and did not feel any difference.
 

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28 MPG avg @ 80 MPH on a 528 mile trip. 2.73's spinning at just under 2,000 RPM. 91 octane.
Okay, but you didn't save any money.

Using today's prices at my local station... 3.569 for regular and 3.889 for premium:

Premium fuel => 528 miles at 28 mpg => 18.86 gallons @ 3.889 = $73.35

Let's say you only get 26 mpg using regular => 528 miles at 26 mpg => 20.31 gallons @ 3.569 = $72.49

The difference is not dramatic and the car may run better using the higher octane but it is certainly not saving you money through better gas mileage.
 

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I think that a tune is necessary to advance the timing so that you get the real benefit of using 91. Before getting the Bama Tunes/SCT tuner, I switched between 87 and 91 and did not feel any difference.
Actually the V6 ECU does advance the timing when you put high octane fuel in the tank. See the article on the V6 Engine in "Muscle Mustangs & Fast Fords."

"Ford also worked outside the engine to make the package a better fit for the Mustang. The powertrain ECU has been upgraded with a very aggressive deceleration cylinder shutoff for fuel economy, coupled with very rapid tip-in for street performance. On the flip side, the ECU has been reprogrammed with adaptive-knock spark control. If the two knock sensors embedded in the cylinder block don't hear knocking, the ECU will keep advancing the spark until it does.What this means in performance terms is that, if the owner uses premium or race gas on weekends, the engine should make considerably more power and torque than the numbers quoted here, which are the product of standard SAE dynamometer laboratory testing procedures and not real-world driving."

2011 Ford Mustang V6 Engine - Muscle Mustangs & Fast Fords


 

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I've been reading through the forums about whether 91 or higher octane in a stock 2011 V6 makes a difference and a lot of people seem to think higher octane is better. I've tried 91 octane wihtout any ethanol and I can't tell any difference from 87 octane with ethanol. If 91 octane makes a difference, why does the owner's manual say to use 87 octane?

2011 Ford Mustang 3.7L V6 Engine - Muscle Mustangs & Fast Fords
you wont feel the difference if you drive like a granny... the throttle is there for a reason...use it.... then come back to us
 

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Discussion Starter #14
So is it better to get Shell V-Power 91 octane without ethanol or should I just stick with regular 87 octane with 10% ehtanol? I tried a full tank of Shell V-Power and I seemed to get slightly better gas mileage, but if the V6 was designed to run on 87 octane is running 91 octane bad for it?
 

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Okay, but you didn't save any money.

Using today's prices at my local station... 3.569 for regular and 3.889 for premium:

Premium fuel => 528 miles at 28 mpg => 18.86 gallons @ 3.889 = $73.35

Let's say you only get 26 mpg using regular => 528 miles at 26 mpg => 20.31 gallons @ 3.569 = $72.49

The difference is not dramatic and the car may run better using the higher octane but it is certainly not saving you money through better gas mileage.
Oops. Sorry. I should go back to running 87 octane. Clearly 91 is a waste. No benefit whatsoever.
 

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So is it better to get Shell V-Power 91 octane without ethanol or should I just stick with regular 87 octane with 10% ehtanol? I tried a full tank of Shell V-Power and I seemed to get slightly better gas mileage, but if the V6 was designed to run on 87 octane is running 91 octane bad for it?
the ecu will adjust timing depending on what you put in it so it really doesn't matter what you put unless you get a tune that requires a certain grade
 

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So is it better to get Shell V-Power 91 octane without ethanol or should I just stick with regular 87 octane with 10% ehtanol? I tried a full tank of Shell V-Power and I seemed to get slightly better gas mileage, but if the V6 was designed to run on 87 octane is running 91 octane bad for it?
You will almost certainly get better mileage with the V-Power - not because of the higher octane but because of the lack of ethanol. Ethanol has about 35% less energy by volume than gasoline so E10 (10% ethanol) will generally give you about 3.5% lower fuel mileage compared to gasoline. The difference in price probably wouldn't justify the small difference in mileage but I find the car feels stronger on real gas than E10.

It won't hurt your engine to run the higher octane fuel. The computer compensates automatically.
 

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Oops. Sorry. I should go back to running 87 octane. Clearly 91 is a waste. No benefit whatsoever.
Your sarcasm is misplaced. All I said was that 91 octane doesn't produce enough difference in mileage to justify the difference in cost. You may find performance benefits with the higher octane that make the cost worthwhile - especially if the higher octane gas is pure gas without ethanol.

But maybe I should use shorter words... 91 costs more than you save in gas but may be more fun to drive. :shigrin
 

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I use Shell V-power now and here are the results,

Regular 87 octane:

Average =420km to 480km mixed city/highway

Throttle response not good most of the time

Shell V-power 91 octane:

Average = 480km to 540km same mixed city and highway.

Throttle responce was cleaned up considerably.

Engine sounds better and idles better

For that extra 7 bucks to fill up the tank i'd say it was worth it.
 
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