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402 Motoring 03-15-2011 07:41 AM

MPH expectations with an 05 5.7
 
Hi guys,

I've have had this 05 Limited with a 5.7 for just over a week now and did my first MPH test. Looks like I'm getting just over 15 mpg's. The truck is bone stock, and I have no record of when or if the truck had a tune up etc. My plans of course is to give the truck a full maintenance makeover plus add a AFE CAI, Diablo tune and a SRT style exhaust when I get into the bodywork.

My question is, for the guys that have this same truck, what is your average mpg's and if you have added a CAI an other engine modifications have you seen an increase in mpg's? Now I realize these trucks are not econo boxes but a freind with a 5.7 Magnum with a Fri cam does get better mpg then this truck. I'm hoping to get at least a couple mpg gain with what I want to do.

This would make the wife happy too....LOL.

Thanks

LTrainGC 03-15-2011 07:58 AM

Re: MPH expectations with an 05 5.7
 
When I was running around in my 05 I had the AEM intake, MBRP cat-back exhaust, and was running Superchips 91 tune w/ MDS disabled I averaged about 18 MPG with about 75/25 highway/city mix. I could get 20-21 on the highway and pure city driving it was down around 14-15.

mrmotoguzzi00 03-15-2011 08:10 AM

Re: MPH expectations with an 05 5.7
 
Interesting.... 402 I just bought my 06 5.7 Limited a month ago, also totally stock(but not for long). In the blizzards around NH in Feb I was averaging around 12, it's around 15 avg with some highway and a fairly gentle right foot... cruise on at 70 I avg 16-18...

what do people run for tire pressures ? i'm at 30 cold, 34 hot... too low ?

ltraingc 20 on the highway ? how fast ?

402 Motoring 03-15-2011 08:19 AM

Re: MPH expectations with an 05 5.7
 
Quote:

Originally Posted by LTrainGC (Post 375796)
When I was running around in my 05 I had the AEM intake, MBRP cat-back exhaust, and was running Superchips 91 tune w/ MDS disabled I averaged about 18 MPG with about 75/25 highway/city mix. I could get 20-21 on the highway and pure city driving it was down around 14-15.

Well thats a great endorsement for mods. I can tell my wife that its not a waaste of money! LOL>

mrmotoguzzi00 03-15-2011 10:37 AM

Re: MPH expectations with an 05 5.7
 
:lol: You are so right!

LTrainGC 03-15-2011 10:50 AM

Re: MPH expectations with an 05 5.7
 
Quote:

Originally Posted by mrmotoguzzi00 (Post 375801)
Interesting.... 402 I just bought my 06 5.7 Limited a month ago, also totally stock(but not for long). In the blizzards around NH in Feb I was averaging around 12, it's around 15 avg with some highway and a fairly gentle right foot... cruise on at 70 I avg 16-18...

what do people run for tire pressures ? i'm at 30 cold, 34 hot... too low ?

ltraingc 20 on the highway ? how fast ?

20 on the highway, cruise set between 65 and 70. This is flat Florida highway too.

If I remember correctly, I was running somewhere between 34 and 36 PSI cold in all my tires.

When I got my 2.25" rocky road lift and 255/70/18's on the JK Sahara 18's, my average MPG dropped about a half mpg.

Chaoul1 03-15-2011 11:37 AM

Re: MPH expectations with an 05 5.7
 
What's the mileage on the Jeep? Maybe it's time to do a little tune up: change spark plugs/wires and PCV Valve.

LTrainGC 03-15-2011 12:54 PM

Re: MPH expectations with an 05 5.7
 
I agree with Paul. With a fresh set of plugs, new PCV valve and all fresh fluids (oil/trans/TC/diffs), I picked up about a half MPG. My oil fluids weren't in bad shape though, so if yours are bad I'd expect a bit more of a MPG increase.

402 Motoring 03-15-2011 02:55 PM

Re: MPH expectations with an 05 5.7
 
Quote:

Originally Posted by Chaoul1 (Post 375912)
What's the mileage on the Jeep? Maybe it's time to do a little tune up: change spark plugs/wires and PCV Valve.

I got it with 110K and I don't have any maintenance records on the truck. It was originally from Colorado passed through Massachusetts before ending up here in Jersey. I plan a complete fluid change and tune up in the near future as well as a AFE CAI and Predator tune. The exhaust will have to wait til I find the time to get my SRT stuff on the truck. Most likely I'll do a quick repaint so everything is fresh at that point too.

Walt 03-19-2011 12:09 PM

Re: MPH expectations with an 05 5.7
 
Quote:

Originally Posted by mrmotoguzzi00 (Post 375801)
Interesting.... what do people run for tire pressures ? i'm at 30 cold, 34 hot... too low ?....

33 psig cold is specified for the '08's and will improve your mpg's. I run 34 psig when I fill them.

There should be a little sticker inside the driver's door on the bodywork. It shows stock tire size and recommended tire pressures. Can increase them by 1 psi if you want without problem, provided that value does not exceed the max pressure on the side of your tires. [It probably won't.]

When all is right with the world, I get 16.7-17.3 mpg mixed driving and 19.5-21 mpg highway (70mph).

...just another data point for your collection. :)

08limited 03-19-2011 10:04 PM

Re: MPH expectations with an 05 5.7
 
wish i got that mpg i have a 08 hemi wk with 50.000 mi and only getting 12

MasterWK 03-19-2011 10:19 PM

Re: MPH expectations with an 05 5.7
 
My 2010 gets 13.1 average. How aggressively do you drive? If you want more just cool it down, but I think the sticker says 15 city... You're fine IMO.


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