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Back from Iraq & lovin it
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So as some of you all know I have been at Drill Sergeant school for the last nine weeks. Great time might I add:crazy:

So anyways I ran from Fort Benning to Fort Jackson and back a couple times using 87, 89 and 93 octane. The test was to see what if any the difference is in the MPG and performance between the grades.

So I took the same route every time and traveled at about the same time to keep the traffic as equal as possible.

I have one important note for this test. I am running after market rims and tires. The tires are the Nitto Mud grappler 33"s so they are not the best for the highway.

So here are my results.

87 octane got me an average of 14.5 MPG

89 octane got me an average of 15.0 MPG

91 octane got me an average of 15.0 MPG

So over the three grades there was basically no difference in MPG but there was a noticeable difference in power.

The 87 was low on power and took a little longer to get up to speed. But the most noticeable was the getting up a hill, the truck would downshift a lot sooner and still feel under power.

The 89 and 91 had basically no noticeable difference.

So I think I am going to stick with the 89. Hope this helps everyone. Feel free ask any questions you can think of. And remember my tires real hurt my MPG but I was hoping to show the difference in the grades.
 

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09 HEMI
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Good test.. I guess i will start with 89 octan today!
 

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I've been getting ~17.5mpg on winter grade 87 octane gas. A couple weeks ago, Costco ran out of 87 and were selling the 91 for the same price. I gave it a shot and my mileage increased to 18.8mpg. Hard to say if this is a one off event or not..as i'm too cheap to keep using 91. I'm not sure if the mileage increase is worth the extra cost of fuel either.
 

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If you have a 26 gallon tank. Around my area 89 is .$10 more than 87. It would cost $2.60 more to fill your tank with 89. According to the his test results he obtained a .5 mile/gallon increase. That is 13 more miles per tank. So you are paying $2.60 for 13 more miles and the added power. I would say it is worth it. Excellent test, Thanks
 

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I got over 20 mpg with a mix of city and freeway. the best ive seen was 25mpg on a freeway trip with 89 octane. My average is about 18.5 and I like to go well over the speed limit. I have the 4.7L by the way
 

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Thanks for the info.

Just a side note on my mileage from a trip last week.

Using 87 octane:
Cruise control set to 70 mph - 18.6 mpg.
Cruise control set to 55 mph - 24 mpg.
 

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marsolais
Please accept the deepest gratitude and thanks from myself and all my family for your service to our great country.
 

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Victims arent we all
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i always thought changing octane grade,lead to pinging in engines or was that a thing of the past?
 

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heminut
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Ramlion: With these new control units,they analize the exhaust and

many other inputs and adjust accordingly.I have even tried on an 9% grade at 5th with my TRX4 and 392's and cant make it ping ...even on the garbage gas we have here in the northern mountains of Penna. In fact,last friday,on my way to my "cancer free" checkup,I was able to overcome the traction and broke em free a few times. I drive 150 miles to the VA hospital in Erie,Pa. and fill up and it jumps from 15.5 to almost 18. I had the same deal going to Atlanta,once away from these old,old refineries,I get 18+ at 75-80 on cruise. All Ive done is an K&N and a 50HD Flowmaster. I LOVE my Ram !
 

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i always thought changing octane grade,lead to pinging in engines or was that a thing of the past?
These motors were tuned for 89 octane but have knock sensors that allow you to run 87 by retarding the timing. They get the advertised 390 hp using the 89 octane and your power will be down slightly when running 87.
 

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And just like I tell everyone, increasing octane higher than the recommended rating (or what you need if you have mods) is pointless.

Time and time again I hear people talk about better mileage with 91 over 87 and how their engine runs cleaner... I try to explain to them, but they are always smarter.

Thanks for the tests, now maybe people will understand that you should run 89 octane, although the manual says its OK for 87 to be put in.
 
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