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How to Improve Gas Mileage in 5.7l HEMI?


Old 04-12-2012, 07:26 PM
lhousesoccer is offline
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Default How to Improve Gas Mileage in 5.7l HEMI?

Hi - I have a 2003 Dodge Ram 1500 Quad Cab, 5.7-l HEMI. I get about 12.5 mpg, regardless of whether I'm in the city, on the highway, or towing my boat. I'd like to boost that up, with the gas prices bouncing at $4.00 a gallon again.

I've heard about the chips you can add to the engine that helps increase gas mileage. Does anyone have any REAL WORLD experience with these? Do they really work? Any side effects? Any tips would be appreciated!
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Old 04-13-2012, 12:49 AM
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Old 04-13-2012, 02:00 AM
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Chet Ubetcha
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The cheapest fuel saving mod you can do is buying a lighter right shoe...

Other than driving style, an e-fan and gears would net you some discernible mileage increases, most likely, but there's an investment before actual returns are seen and felt in the wallet. I don't have a SC tuner yet, but from what I've read on here, the "fuel mileage" tune is not really productive.

*EDIT* Also make sure that your tires are properly aired (the smaller and lighter the tire, the better for mileage), your plugs are serviceable, fluids are clean and full synthetic and your sensors and throttle body are clean of gunk and carbon buildup. Just general maintenance can yield the best results.

Last edited by Chet Ubetcha; 04-13-2012 at 02:02 AM.
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Old 04-13-2012, 08:27 AM
Gone Fishin
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Chet pretty much nailed it. The e-fan would be a great place to start, AFTER all the regular maint. items get covered. Basically, its a big high wind resistance block with a lot of weight.

I have a Diablo tuner on mine and with the "econo" tune all it really gets you is a really doggy acceleration when you really need it. No noticeable improvement in mileage. And I measure mine by calculation---not overhead.
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Old 04-13-2012, 09:30 AM
lhousesoccer is offline
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Yeah, I'm running 20" factory rims with P265/75 tires. All stock. I ran my first set of tires for 8 years before I finally had to replace them with a new ($1,000 !) set last summer, so I do make them last by keeping them well inflated. Overall, I keep my Dodge super maintained. The 12.5 mpg hasn't changed since the day I picked it up. I think it's time to start looking for another pickup that might give me 20 mpg or so, as long as I can tow with it. But it's hard to think about dropped $30K or more on a new truck, when mine is paid off, just to save $400 a year on gas.
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Old 04-13-2012, 11:29 AM
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The factory 20s are costing you a bit at the pump, 17s with the same diameter tires would gain you around 2 mpg - probably the biggest bang for the buck. E-fan is a great mod as the initial cost is low and can be made up with fuel savings within a year. Anything else except a good tune up and using synthetic fluids wherever possible will just cost too much for the gains to be made up at the pump without waiting beyond the life of the truck.

I'm pretty much in the same boat, I average about 13.5 and my daily driver's engine just decided to take a sh*t VERY prematurely! Which means that for the first time since 2005 my truck is my daily driver. But any major changes to the truck would just take WAY too long to make back at the pump.

Trading in a paid off truck in good working condition for one that might net you 2-3 more MPG just isn't going to be cost effective either. You'll have more in one month of payment than it'll save you on gas in a year...
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Old 04-13-2012, 11:50 AM
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Your going to have spend money to gain any increase in mpg, the issues are that tunners CAI and ex work still can buy a you lot of flue, yes over time they pay back, but up front costs are real time money to gain some mpg potential in a truck that was never designed for mpg contest's.

The baisc boaring stuff, tire psi, tune ups, oil changes, mainatance are the best bang for the buck, also 17 in rims and tires as per HammersZ71 post.

Last edited by cyclone429; 04-13-2012 at 11:53 AM.
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Old 04-13-2012, 03:00 PM
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When my 5.7 was bone stock I was avg around 15.5 mpg and after cai, exhaust, diablo intune 91 tune, and e fan I avg 18.1 hand calc'd. E fan is major when city driving. I was getting about 9 mpg via overhead display, after fan it's up to 13 mpg. I dont know if that's the case for everyone but it has been the best upgrade by far IMO.
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Old 04-13-2012, 03:43 PM
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A 50% increase from the e-fan?! Not likely.
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Old 04-13-2012, 04:00 PM
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man hammer. i think you are getting a bit forgetful. what about that startron stuff you are always preaching about for all the people that can't find ethanol free pumps?
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