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Thoughts, Cat-back exhaust = better mpg?

Rubiwoo

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I searched, didn't find much.

I know in the past with my other cars changing the exhaust yielded 1-2 extra mpg. Never owning a Jeep before, was curious if the same would apply toward the Gladiator?
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saltlife4shore

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Its possible. I dont know what types of cars you had before but to me a quiet V6 at 18mpg is better then an annoying sounding V6 at 19mpg.
 

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Exhaust alone (without a tune) will not improve anything but sound. These systems flow extremely well and are designed to optimize efficiency. If you get a tune it might get you some increase mpg but exhaust alone will not. I have done the flow testing and it is very optimized.
 

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I searched, did find much.

I know in the past with my other cars changing the exhaust yielded 1-2 extra mpg. Never owning a Jeep before, was curious if the same would apply toward the Gladiator?
This doesn't happen with current vehicles today. Same as Cold air kits. Looks and sound for both.
 

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Exhaust alone (without a tune) will not improve anything but sound. These systems flow extremely well and are designed to optimize efficiency. If you get a tune it might get you some increase mpg but exhaust alone will not. I have done the flow testing and it is very optimized.
can you post the data from that testing please? I'd be really interested in seeing it. thnx
 
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Exhaust alone (without a tune) will not improve anything but sound. These systems flow extremely well and are designed to optimize efficiency. If you get a tune it might get you some increase mpg but exhaust alone will not. I have done the flow testing and it is very optimized.

I would also like to have a look at the data.
 

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So I'm older tam most here at 60. I have done cat back. Headers and full systems, Cold air intakes to at least 15 trucks. I like to do it let's me play with my truck. I like the sound of a V8. I will not on this V6. Never have I ever got a 1 mpg gain. No one else has either. If a better flow helped it would come like that. So do it if you want and don't let us stop you from messing with your truck. Just sounds a little different than a V8.
 
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If a better flow helped it would come like that.
My understanding is,, The manufacturer is required to meet certain regulations, pollution control, sound, etc... removing 3 mufflers with a high flow should yield more efficiency.

I don't have tests to back any of that up, but in theory...
 

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Been working for tuning companies since 2005 Diablo, SCT, Edge & Superchips . At Hamburger's we have dyno tested and I drive 30k+ miles a year in Jeeps alone around the country. I gained 15hp with exhaust. Dyno tested and road tested CAI, drop in Green filter, and stock, the gains were 1-2hp but that can easily be other factors between pulls.
 
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Rubiwoo

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Been working for tuning companies since 2005 Diablo, SCT, Edge & Superchips . At Hamburger's we have dyno tested and I drive 30k+ miles a year in Jeeps alone around the country. I gained 15hp with exhaust. Dyno tested and road tested CAI, drop in Green filter, and stock, the gains were 1-2hp but that can easily be other factors between pulls.
But what about mpg's?
 

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Not possible. Google "stoichiometric ratio". The engine controller is programmed to automatically maintain the proper air/fuel ratio. IF you were somehow able to throw more air at the engine via intake or exhaust modifcations, then you'd automatically be throwing more fuel at it also.

In addition to that, people who get aftermarket exhaust almost always drive more aggressively so they can hear the sounds of that exhaust, which worsens the effect.

Bottom line is, with intake/exhaust mods you will see a decrease in MPG, not an increase.
 

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youll pick up WOT power on an intake if there is the fuel for it. So on a stock tune, it will generally only be 5k on up after the manifold has swapped runners, you're on the bigger cam, and it's actually fueling. Below that, you're adding air to an area that was already too lean. It will improve slightly with long term fuel trim adaptation as it carries over to the tables. In closed loop operation you can manipulate trims to your advantage by removing the restriction. and the stock airbox is a restriction for sure. 1-2 at peak with an intake seems pretty off to me, but different runs/parts/trim time all play a factor.

Claims that exhausts on these truck flow well or wont pick up power is also false, and supported by zero data. The exhaust on these trucks is a restriction even stock, and it gets more so as power increases. It isn't a fueling/tuning dependent as an intake, obviously, but it's definitely there throughout the RPM band because of the pumping efficiency gained by a higher exhaust.

I wont claim that any single item causes massive change to power or MPG on it's own outside of tuning, but I have remained consistently above 20mpg with intake, exhaust, and a pulsar that does minimal changes to closed loop operation since going to 37" tires. before I lifted 4", i was getting as high as 23. so, yes, they are restrictions...all of them...the intake, the exhaust, and tune are all massive restrictions to this system. I dont do it (and no one should) trying to recoup money through MPG gained. I did it because I wanted the truck to drive well and increase my tank range for long fuel stops while in the boonies. I also like the way the exhaust sounds.

There is a ton of information on this topic readily available on this forum if you search for it. The problem is the voices of the people who actually understand this stuff and actually do any testing on it are too drowned out by people on the internet who don't know anything beyond what the person above them posted on a forum 10 years ago. Lots of people learn the terms, few people actually understand how any of it works. I've done what I can to teach, but only the willing can learn.
 

KurtP

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Not possible. Google "stoichiometric ratio". The engine controller is programmed to automatically maintain the proper air/fuel ratio. IF you were somehow able to throw more air at the engine via intake or exhaust modifcations, then you'd automatically be throwing more fuel at it also.

In addition to that, people who get aftermarket exhaust almost always drive more aggressively so they can hear the sounds of that exhaust, which worsens the effect.

Bottom line is, with intake/exhaust mods you will see a decrease in MPG, not an increase.
This is incorrect.

stoich is only a part of how the engine pumping works and what the ECU is doing to fuel adaptations, and has to be considered in aggregate of a piece of equipment in motion against air resistance. Throttle angle, load, wind resistance, rolling resistance, etc all get a say in what effect stoich closed loop operation has on a driving vehicle.

Stoich mix at closed loop operation doesnt happen in a lab, where the only factor of fuel economy is the raw amount of fuel sprayed.....
 
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KurtP

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So I'm older tam most here at 60. I have done cat back. Headers and full systems, Cold air intakes to at least 15 trucks. I like to do it let's me play with my truck. I like the sound of a V8. I will not on this V6. Never have I ever got a 1 mpg gain. No one else has either. If a better flow helped it would come like that. So do it if you want and don't let us stop you from messing with your truck. Just sounds a little different than a V8.
This is incorrect.

There are multiple exhausts that make 10+lb/ft of tq through chunks of the rpm band on an otherwise stock truck on the market today. You wont ever see your money back on MPG difference, and any noise that results may or may not be worth it to you, but to say the stock exhaust is as efficient as others is incorrect.
 

jeepin48

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Take your entire cold end off and run around with just your Y-pipe. Yes it will be loud, but do your best to drive the same and see if you get your MPG to increase......... I can't post results unfortunately. As much as the Stellantis fights for MPG, they are not going to leave an easy gain on the table like exhaust mod.
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