3.6 - For Those Running Premium Fuel

Goosed

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For those running premium fuel, what are you seeing (MPG increase and overall improvements if any).

I’m seeing the 3.6 is 11.5:1 compression, and more and more forum discussions for other vehicles that run the Pentastar are using premium with good success.

weather and wind have been fairly consistent here in NE Ohio and over the last 6 days I ran through 2 tanks, seeing just over 3 MPG better on highway runs back and forth to the same place helping my father in law move his inventory from a Snap On truck.

was getting 17 to 17.5 MPG andover the last two tanks of premium have been seeing 20.7 to 21.1. Didn’t have any knock issues or anything before this so running performance (if you can call the Wrangler anything performance related) hasn’t changed much.

Just interested in other feedback.
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Bearded_Dragon

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Tried running 93 octane for a month to help reduce random knocking at low RPMs and moderate load. Saw zero difference in prevention knock, performance, or MPG.
 

Tread4Lo

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I don't see how you guys are getting these MPG's out of the Pentastar. I'm getting about as good as my old 3.8L was doing with a manual transmission.

I'm going to try the next few tanks with Premium. It's gotten hot AF down here in Texas with high humidity, maybe the timing has been screwed with.
 

Chocolate Thunder

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I don’t know the cause of your 3+ MPG fuel efficiency increase, but it’s not from using higher octane fuel. It’s not physically possible. It’s great to use if you have knocking, but it doesn’t increase fuel mileage.

But it’s your money and if you lbelieve that it does, who am I and the laws of thermodynamics to tell you different.
 

VerservJL

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My work covers the majority of my fuel cost so I have plenty of mileage on each. I can barely tell a difference between 93/91 and 87. This engine barely seems to care either way.
 
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Goosed

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I figured this would cause a uproar but for info...

I made 26 trips in total, 21 miles one way same roads each time. Weather has pretty much been the same, mid humidity, 85-90 degrees, non-existent wind. Same trip, 21 miles each same highway same times Of the day roughly. Top fully on for the entire time because I sweat if it’s above 50 degrees. So really the only thing that changed was the fuel grade. So how else could it be anything but the fuel?

Also, this was with some payload as I was hauling some weight vs. when I was hauling nothing with 87 octane and getting 17-17.5.
 
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Goosed

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I don’t know the cause of your 3+ MPG fuel efficiency increase, but it’s not from using higher octane fuel. It’s not physically possible. It’s great to use if you have knocking, but it doesn’t increase fuel mileage.

But it’s your money and if you lbelieve that it does, who am I and the laws of thermodynamics to tell you different.
Investigate and research the 3.6 a little more and it may surprise you that the higher compression engine thrives on higher octane fuel. Believe Livernoise just posted something about their tuner recently and also provided background info on how much better the 3.6 delivers all around with premium fuel. I can’t find the thread right now but I’ll post it if I can.
 
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Goosed

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