Disappointing Highway MPG after Mods

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phillips66

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Ram is 2013 CC 5.7 6 speed. I have S&B CAI, 87 TB, Catch Can, & Bully Dog Tuner set to stock as I run 87 octane. Driving from Texas to Illinois, and all highway, maybe 300lbs in the bed with 4 adults in the cab running a/c the whole trip. My first tank I got 18.1 mpg (hand Calculated) driving the Texas, Oklahoma Speed limit of 75. On my second tank I got 19.5 mpg (hand calculated), this time I had cruise set at 71, Missouri, Illinois speed limit.

With the mods I have my city driving went from 15 to about 16.5 on average, thats a gain of about 2 which I think is good. According to the window sticker the estimated mpg is 15/19. if i can gain the 1.5 in the city why wouldn't I have gained at least 2 to 3 mpg on the highway? I'm not complaining about getting 19.5, but would have liked to have seen 20 to 21 or even more.

On the trip down I was towing a 6x12 Uhaul Trailer, we won't talk about that mpg...:emotions133:

Actually it wasn't bad, I got 13 most of the trip with exception of going thru the hills on the eastern side of Texas.

Back to my question, is there anything I can do to improve my highway mileage? Would swapping out muffler and Y pipe help? I'm open for any suggestions.

Thanks in Advance.
 

Chewy

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Muffler may help some, but I'd say your speed is what's killing you. The EPA doesn't test and get the MPG figures at those speeds. I'd say what you got is spot on.
 

Casper

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^^ditto. Your Ram is a big brick pushig a lot of resistance at 70+ mph.
 

Ona4day

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Pretty sure our window est. is 13/19 Ave 15. Not that those are correct. I pretty much run the same set up but with 91 and a "standard" tune. My average is all based on how I drive it. I drove from Cali to Boise ID and got 19.5. My overall average is in the 15 range. I was expecting power gains and that's what I got, not really a bump in mileage.
 

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Those mileage numbers are actually pretty good, especially for 87 octane at those speeds. It is going to be tough to see a consistent 20mpg average in these trucks.
 
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phillips66

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My bad, 13/19, but if i gained about 3 from the city I would have liked to see the 3 on highway too.

Thought muffler might help with better flow?

I understand these trucks are tanks, just wanting to know if there is anything else I could do.
 

Designflaw

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Pretty sure our window est. is 13/19 Ave 15. Not that those are correct. I pretty much run the same set up but with 91 and a "standard" tune. My average is all based on how I drive it. I drove from Cali to Boise ID and got 19.5. My overall average is in the 15 range. I was expecting power gains and that's what I got, not really a bump in mileage.

You are correct - the window sticker clearly states 13/19 Average 15 - I set my Trip B when I change Oil and in 3000 miles I average 13.4 with 60/40 HIghway and about 20% of those miles I was pulling something so I guess its close. I have NEVER gotten 17 mpg on any highway trip and I try to lock it at 73. I just have the Catch Can (just added for the last 500 mile trip) and the Air Grabber

Those mileage numbers are actually pretty good, especially for 87 octane at those speeds. It is going to be tough to see a consistent 20mpg average in these trucks.

I agree, I would :leghump: for those numbers
 
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phillips66

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I guess on my next trip I will slow it down a little and see if it makes a difference. Like I said I am very pleased with 19.5 and with the 32 gal tank, I can dam near go 550 miles on 1 tank.

I did just tow a open 12 foot trailer with 3 quads on it, up into Wisconsin and got 14.7, I will take that all day, and that was doing 68 going and 70 return.:headbang:
 

Ramunit

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Personally, if I wanted max mpg's I would leave my truck COMPLETELY stock and drive like grandma.
 

TylerB

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Like Chewy said, the EPA doesn't estimate based off those speeds, more along the lines of 55mph, backwood "hi-ways" not Texas interstate. I think you're doing damn good for what you're hauling at those speeds. I was lucky to average 21mpg at 70mph with just me and the wife.
 

WhiteExpress

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You could try some aerodynamic tweaks: partial grill block, belly pan, bed cover.
Might help, might not.
 

Chewy

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You could try some aerodynamic tweaks: partial grill block, belly pan, bed cover.
Might help, might not.

His '13 should have the louvers behind the grill...

Taping up all the body lines helps though. Like where the headlights and front grill hit the bumper and fenders and where the hood and fenders meet.

Personally, I wouldn't bother! Such a PITA to do.
 
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phillips66

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His '13 should have the louvers behind the grill...

Taping up all the body lines helps though. Like where the headlights and front grill hit the bumper and fenders and where the hood and fenders meet.

Personally, I wouldn't bother! Such a PITA to do.

I do have a Tonneau cover but i thought the Louvers were only on the V6 8 speeds. I don't believe I have them.
 

WhiteExpress

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Eh, the 'active grill shutters' are only so effective.
The air still builds up a nasty pocket behind the grill etc.

I messed around with this on my '00 Ram 4x4. I did a full grill and bumper block (it was chilly winter weather) I gained... NOTHING! I didn't see more than a .2 MPG change, and that's in the noise as far as I'm concerned. But it was leveled on 34s on heavy cheap 20s.

Just saying, Aero helps some, especially at speeds.
 

emjohn4

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60mph and you'll gain the missing MPG you want.
 

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Here in TX, we don't drive 60mph. Most of our highways are 70-80mph speed limits. If you are going 60mph, then you will get run off the road...haha.
 

Chewy

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We have 70mph here in IA too as long as it's not near a town. Most go 78 or so though.

I think the point is, the EPA ratings aren't real world numbers (which is total BS). Drive the vehicle out on the highway with all the other traffic at posted limits just like the cars owner will be.
 
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