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  #61  
Old 05-10-2012, 03:02 PM
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Re: Official post your mpg's.

Hitch, it's because of the altitude you're at. Rule of thumb is one octane point less required for every 1000 ft. increase in elevation. When I travel at higher altitudes (I am at ~3000 ft.) I'll almost always run 85 in my Hemi. I don't think it affects the fuel economy that much, but then again, most of it it highway driving. Since camming my vehicles, I now alternate 87 and 91 non-ethanol fuel, except in the summer and when I go racing. Then they get all 91.
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  #62  
Old 05-10-2012, 09:54 PM
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Re: Official post your mpg's.

Aaahh thanks I never knew that. So you're saying the lower octane is actually better for my engine up here? But I definitely noticed a difference in mpg...?
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  #63  
Old 05-10-2012, 11:32 PM
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Re: Official post your mpg's.

Quote:
Originally Posted by jeepgcoman View Post
Hitch, it's because of the altitude you're at. Rule of thumb is one octane point less required for every 1000 ft. increase in elevation. When I travel at higher altitudes (I am at ~3000 ft.) I'll almost always run 85 in my Hemi
idk about this.... Why would you put gas with less octane(less oxygen) in a vehicle at a higher altitude? vehicles at higher altitudes are already starved of power, and putting gas with less octane would, if I'm correct, only starve it of even more power!

I don't think less would be more in this case...

And down here it's 87, 89, 93 octane
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  #64  
Old 05-12-2012, 06:20 PM
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2012 Hemi, driving conservatively with a occasional lead foot lapse:

15 city
17/18 mixed
19.5 - 21 highway
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  #65  
Old 05-12-2012, 07:09 PM
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Re: Official post your mpg's.

Quote:
Originally Posted by djva076 View Post
2012 Hemi, driving conservatively with a occasional lead foot lapse:

15 city
17/18 mixed
19.5 - 21 highway
Any mods?
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  #66  
Old 05-13-2012, 12:16 PM
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Re: Official post your mpg's.

Quote:
Originally Posted by hitch View Post
Aaahh thanks I never knew that. So you're saying the lower octane is actually better for my engine up here? But I definitely noticed a difference in mpg...?
Hitch and 05WK, there are many articles and threads on different forums addressing this issue. I'll ref. a couple, but if you want to know a little more about this, I just plugged in, "fuel octane requirements at altitude". It came up with a bunch of stuff. Here's just a couple:

http://www.snowestonline.com/forum/a.../t-249677.html

http://www.texaco.com/in-the-know/fu...px?tc=22&qc=50

http://www.thumpertalk.com/topic/937...e-vs-altitude/

All this being said, I can say that my compression pressure at a density altitude of ~4500 ft. runs ~150-155 PSI. If I were to do a compression test at sea level it would probably be closer to 200 PSI. IMO, you're just wasting $$$ by running real high octane fuel in a relatively stock motor, when at altitude. Even with my cammed Hemi I still alternate 87/91 every other tank, except in the summer when I'll run all 91. I've also gotten some of my best fuel economy (FE)going over the mountains between Reno and Salt Lake, using 85. I find, for me, under normal driving (which is difficult) my FE is slightly worse with the higher octane. Just check out some of the ref's. and do a little experimenting, and let us know what conclusions you come up with. One other thing, if you can get hold of non ethanol laced fuel (like I can most of the time), you'll also find it to be a little better on FE. Keep us posted.
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  #67  
Old 05-14-2012, 12:41 PM
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Quote:
Originally Posted by 05WK View Post
Any mods?
No mods unless you count side steps and a hitch mounted bike rack.

It may be worth doing a reset for each condition and being doubly careful not to allow highway numbers to be any part of city and vice versa. I'll run the numbers again and report back soon.


Sent from my GT-N7000 using Tapatalk 2
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  #68  
Old 08-15-2012, 10:49 PM
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Re: Official post your mpg's.

Every day around the town driving I get around 11 or so. Highway about 19 and 15 towing my 2,500 lb pop-up trailer. I have the 4.7
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  #69  
Old 08-16-2012, 10:16 PM
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Re: Official post your mpg's.

Quote:
Originally Posted by jeepnjeep View Post
Every day around the town driving I get around 11 or so. Highway about 19 and 15 towing my 2,500 lb pop-up trailer. I have the 4.7
Well those tires aren't helping you any on MPG's...

Whats your mileage and have you done basic tune up steps to improve the engine performance?
-All fluids
-Sea foam
-Plugs
etc...
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Old 08-18-2012, 09:42 AM
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Re: Official post your mpg's.

Just did a 2000 mile road trip, did 19.8 mpg on average, doing 16.8 mpg in the city, but around half is highway. My 2006 WK Laredo 4.7 4WD is basically stock but will be replacing many parts as well as adding new parts. Tires are 3-5/32 thread (Crappy Wranglers) will be replaced by new Michelin LTX A/S2's soon, will be adding cold air intake+airaid throttle spacer soon. Mileage is 195000 km now.
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  #71  
Old 08-18-2012, 10:48 AM
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Re: Official post your mpg's.

TB Spacer is pointless, btw. Just get a ported TB with that CAI
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  #72  
Old 08-18-2012, 12:58 PM
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Re: Official post your mpg's.

Quote:
Originally Posted by 05WK View Post
TB Spacer is pointless, btw. Just get a ported TB with that CAI
Just noticed you have a Fastman ported TB, I'll add that to the list, how do you like the Flowmaster 44 btw? Should I get that for my 4.7? Thx.
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