Super MPG

AbeWay

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Trying to make my 2-door JL super fuel efficient. Thinking of deleting my muffler, there's mo laws in my state about it, but wondering if there's any negative effects. Everyone seems to be pretty divided that it'll do nothing or I'll start it and the whole thing will blow up.

Don't really care about the sound just wondering about engine longevity.
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AZDustMuncher

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I think there is only 2 options for making a Jeep super fuel efficient.

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Dingus

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I ran one tank of gas through my 2 door JL Rubicon before putting on the Magnaflow Rock Crawler exhaust - which is a straight-through muffler. It's not a straight-pipe, but it's considerably more "open" than the stock exhaust.

I record mileage, gallons, dates, fuel types, fuel brands for every fill-up (at least for now, while I'm tweaking things). I don't have the numbers in front of me - and I'm happy to provide them to you if you're curious. But the short story is: it didn't do much at all. I suspect whatever gains you get will be within rounding-error scale.

I'm only a sample set of one - and I only have the one tank pre-exhaust change, so even within there is a small sample set. Given that, I'm happy to be corrected by those that have experiences more impressive than what I have documented.
 

Dingus

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So, very small sample set - but here are my averages to those interested:

15.627 mpg running stock (only one tank)
17.508 mpg with back seats removed and Magnaflow Rock Crawler exhaust (3 tanks of fuel, averaged)
17.626 mpg with a Warn Zeon 10S and winch plate installed (this was mostly highway driving - only one tank)

Inconsistent mix of highway / city driving - so that may come into play here. I'm intending to track relatively long-term just to see trends and play with data.

Again - small sample set, but I could see a claim that the new exhaust helped with as much as 2mpg.
 

nerubi

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So, very small sample set - but here are my averages to those interested:

15.627 mpg running stock (only one tank)
17.508 mpg with back seats removed and Magnaflow Rock Crawler exhaust (3 tanks of fuel, averaged)
17.626 mpg with a Warn Zeon 10S and winch plate installed (this was mostly highway driving - only one tank)

Inconsistent mix of highway / city driving - so that may come into play here. I'm intending to track relatively long-term just to see trends and play with data.

Again - small sample set, but I could see a claim that the new exhaust helped with as much as 2mpg.
Do you drive the exact same course in the exact same conditions of traffic, temperature/humidity, lights, acceleration, weight of vehicle? Those are just some of the factors to take into account to try to understand if any gas savings can be claimed. About the only possible gain could be the weight reduction from changing the muffler. EPA tests indicate reducing 100 pounds of weight can cause an mpg gain of 1%, not 10%. And that is reduced as the weight of the vehicle increases.
So unless you drive downhill every mile you drive you aren't going to do much that can improve your mileage above the EPA estimates for a Jeep no matter what anyone on this forum claims. You can reduce it significantly though by lifting it, putting on bigger tires, roof racks, heavier bumpers, and gear changes..
 

xeon

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Throwing this into the "just having fun" pile. Draft behind big rigs. Dont need to drop weight. Sort of figure thats how got the window sticker MPG LOL
 

DaltonGang

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Trying to make my 2-door JL super fuel efficient. Thinking of deleting my muffler, there's mo laws in my state about it, but wondering if there's any negative effects. Everyone seems to be pretty divided that it'll do nothing or I'll start it and the whole thing will blow up.

Don't really care about the sound just wondering about engine longevity.
Speaking on behalf of those who have to live around a few people, who like to run their rigs without mufflers. I would like to say, you piss off about everyone, except those under 20. It is rude, obnoxious, does very little for milage, and annoys anyone who tries to sleep, while these rigs run around the neighborhood. Don't do it.
 

AZDustMuncher

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Speaking on behalf of those who have to live around a few people, who like to run their rigs without mufflers. I would like to say, you piss off about everyone, except those under 20. It is rude, obnoxious, does very little for milage, and annoys anyone who tries to sleep, while these rigs run around the neighborhood. Don't do it.
^^^^ Also likes to yell at children "STAY OFF MY LAWN"

For me it doesn't piss me off, it just doesn't sound good. Not to say I wouldn't do it myself but I would only do it with other mods like a supercharger, turbo, cold air intake, and a performance tune. It's one thing to be loud and fast, it looks stupid when your vehicle is loud and doesn't go anywhere.
 

DaltonGang

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^^^^ Also likes to yell at children "STAY OFF MY LAWN"

For me it doesn't piss me off, it just doesn't sound good. Not to say I wouldn't do it myself but I would only do it with other mods like a supercharger, turbo, cold air intake, and a performance tune. It's one thing to be loud and fast, it looks stupid when your vehicle is loud and doesn't go anywhere.
Never yelled at kids to stay off my lawn, but one day I aspire to be that crotchety.
 

bmrrwolfe

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Speaking on behalf of those who have to live around a few people, who like to run their rigs without mufflers. I would like to say, you piss off about everyone, except those under 20. It is rude, obnoxious, does very little for milage, and annoys anyone who tries to sleep, while these rigs run around the neighborhood. Don't do it.
I have to say a JL without the suitcase muffler in the back is not that loud nor obnoxious...
You must really hate any Harleys, or a 396 Chevelle.
Edit: For the record I still have my stock exhaust. But have a Magnaflow axle back new in box on Facebook marketplace for $150 that I couldn't pass up and will have on when the weather breaks.
 

Covfefe

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There's no amount of money you can spend on a Wrangler where you will even break even on cost vs mileage
 

DaltonGang

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I have to say a JL without the suitcase muffler in the back is not that loud nor obnoxious...
You must really hate any Harleys, or a 396 Chevelle.
Edit: For the record I still have my stock exhaust. But have a Magnaflow axle back new in box on Facebook marketplace for $150 that I couldn't pass up and will have on when the weather breaks.
No, I just think having really loud exhaust is very rude and obnoxious, in the Suburban Neighborhood. Kind of like when a neighbor has a loud barking dog, all night, or a neighbor throws a loud late night party, when people need their sleep, and work in the morning. People need to think of others rather than themselves, at times.
 

krucam

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