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External modifications and MPG relations

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Old 05-20-2013, 02:16 AM
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Default External modifications and MPG relations

Hey I'm thinking of doing a few things to my xj. Probably a 2" (maybe 3) lift kit, and a home-made roof rack very similar to this one.

http://www.jeepforum.com/forum/f11/b...-70-a-1290752/

I also am thinking about spacing the tires out a little just for a more aggressive stance.

My question is, how is gas mileage affected by these things. I've tried researching some, and have heard from different people many things. Someone said that just their snowboard Yakima rack took down their MPG by 8, other people I have heard say that 2-3" lift kits and roof racks like the one in the link did almost nothing to their mpg.

Currently I have 235s on, has anyone gotten a 3" lift and also spaced the tires out a little more with 325s? Pics? I ask because I don't particularly like the way 3 on 235s look, so I was thinking if I move them out a bit more it might help. Thoughts?

Last edited by JeepN00bie; 05-22-2013 at 02:32 PM.
Old 05-20-2013, 12:55 PM
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something i forgot to mention, if i were to mount the spare tire on the roof rack?
Old 05-20-2013, 02:50 PM
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Anything that adds drag will decrease MPG.
Old 05-20-2013, 03:06 PM
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I'm at 4" on 31's and I lost about 1mpg or so over stock. I don't have anything other thant the stock roof rails up there
Old 05-20-2013, 05:28 PM
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Originally Posted by cleenrob
I'm at 4" on 31's and I lost about 1mpg or so over stock. I don't have anything other thant the stock roof rails up there
X2
Old 05-20-2013, 06:34 PM
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im at 4.5" with 32s and I put my 14ft kayak on top of my xj and went down 4 mpg and its only 80lbs
Old 05-20-2013, 11:12 PM
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Any idea about removing the front air dam on a 3 inch lift? It look butt ugly with lift
Old 05-20-2013, 11:47 PM
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any people with information about roof mounting the spare tire and how it affected your gas mileage?
Old 05-20-2013, 11:51 PM
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You shouldn't put your spare on the roof. But you should weld a giant shark fin onto the top of your XJ. It cuts through the air and should save you an estimated 8-10 mpg. Plus your coolness factor increased by 10. So it's a win win
Old 05-21-2013, 12:08 AM
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You will also hear more wind noise with a roof rack.
Old 05-21-2013, 01:03 AM
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Keep in mind a lot of the people put bigger tires on their jeeps and don't change the speedo gear to compensate so the display says they are going further than they actually are. Estimations don't count.

Anyway I have a factory mopar tire carrier and I lost zero MPG contrary to way I read on forums. Everything else is stock.
Old 05-21-2013, 11:48 PM
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Your in a jeep the mpg is the only down fall we have deal with it
Old 05-21-2013, 11:48 PM
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Old 05-21-2013, 11:58 PM
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Originally Posted by JeepsMyName
Your in a jeep the mpg is the only down fall we have deal with it
I realize that, I'm just trying to get an idea as to the significance in decrease when lifting and/or adding a roof rack.
Old 05-22-2013, 12:09 AM
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Yeah its a good qustion you will not get a definite answer for Intel you do it.


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