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Performance vs economy

7K views 35 replies 12 participants last post by  corneileous 
#1 ·
In January I purchased a 2011 Ram 1500 4x4. It has the 5.7 hemi and auto trans. Love the truck! I've had a 97 and 2000 Ram 4x4s, both with 5.9l 360s. Gas mileage for both were 10 to 11 city and 13 to 15 highway.

When the hemi trucks became popular I saw ads claiming city 13 / 15 and highway 16 / 18. Needless to say I was excited to move up to better efficiency!

That a load of crap! City is 10.5 and highway, 11! I'm talking 55 to 70 mph highway!

Granted, it runs like a scalded dog! Seems to launch from stoplights very aggressively and rpm indicates a higher converter stall than I'm used to.

Here's where I need help. I'm beginning to think it's been chipped. Everything from stall rpm and trans shifts to engine performance makes me think it's been tweaked. How do I tell? This could explain the crappy mileage.

Thanks
 
#2 ·
I'm not very educated in the realm of performance tuning since my current pickup is the first one I've ever experimented with but with mine, I have a Diablosport Trinity Tuner on it and even while running 91 octane fuel in it with the MDS turned off, my fuel mileage isn't that bad....even with the constant flogging on it with the way I drive it!!!....lol. As a matter of fact, if I drive the truck with a little bit of respect, I get a little better mileage than when it was stock. It's not much but, it certainly didn't drop dramatically.

As far as looking for traces of electronic modifications, I'd start looking around the PCM for an inline chip or module. Is there anything plugged into the diagnostic port under the dash, right above the pedals?

If your vehicle has been reprogrammed via tuner, my guess says your only bet more than likely would be to take it to a dealer and have them hook to it and look.

Maybe it's just me but I would think if the previous owner used a programmer on the truck, they would have returned the vehicle to stock before getting rid of it because at least with a Diablosport, before you can reprogram the ECM, you have to save a copy of the stock tune and store it on the device before you can upload the custom tune to it. Plus, if you get rid of the vehicle and don't return it to stock you can't use ur tuner to reprogram anything else. Well, you probably could eventually but it's gonna require getting on the horn with the device manufacturer to basicly reprogram the tuner....lol. Not impossible but, not easy, either.

If this is the case with yours, the dealership is probly ur best bet. Hope this helps.

Maybe someone who has more knowledge about this will chime in and help.
 
#3 ·
Ram Sport

I have a Ram Sport, 5.7 Hemi 3.55 rears 4x4 , 20 inch wheels.. I now have 26,865 on the clock,, and ocasionally tow a 29 ft Prowler tt ,, at 8700 on the scales... Ran 14 mpg in the city and 19.1 the best I could get out of it.. Towing ran no better that 11 with the trailer and in regular drive.. This was 500 miles one way... returned with 13 by running setting in 4th as max and ran 13.8 mpg... I would never dream of towing at 70 mph. I shoot for 55 as my avg. and 60 max with down grade or wind.. Chipped truck with g-force chip and did the same run to Toronto (unloaded) from the North here.. I really didn't expect much change but the same truck averaged 19.8 after the return trip (1100 miles) and indicated as high as 24 mpg on the freeway running 91 octaine fuel.. It will drop by 2 on the highway using reg gas with ethenol at 10 percent.. All highway at 55 to 60 mph.. best eco rpm is 1600 and 1950 with tow on.. (tow in 4th gear locked max) Read " Bobtheoilguy.com" and besure you only use 0w20 or at most 5w20 synthetics and let the oil warm up before working the engine hard.. Cheers and happy trails on the biways... Doug
 
#4 ·
Appreciate the feedback. Gives me some hope but worried about cost. Couple strokes and back issues keeps me from under the dash and $85 an hour at the dealer scares the hell outta me! Lol

I'm an old hardware rodder! Cams, carbs, headers, etc.... That stuff makes sense to me. Computers and ECMs scare the hell outta me! Lol

Can someone describe the perf programmer thing to me?

Thanks, Stan
 
#5 ·
I'm also an old hot rodder... However, my fear of programmers disappeared when I bought a stock 2005 Mustang with the 210hp V6 as a daily commuter vehicle. I got 25mpg on the highway on my daily 150 mile round rip commute.

I quickly tired of the low hp and began adding traditional bolt-ons such as free-flowing exhaust and cold air intake. Other owners of Mustangs were touting the SCT programmers loaded with a custom tune from Bama Tunes. I gave in and bought one loaded with 3 optional tunes; Economy, Performance, and High Performance. By simply plugging in the SCT tuner and pressing a few buttons, I was able to change my timing, shift points, and other assorted witchcraft that the car's computer controlled.

By running 92 octane fuel and selecting the high performance tune, I increased my power to around 285hp. The difference was amazing! My little V6 Mustang was close to GT V8 power levels and it chirped the rear tires and ran 14 second quarter miles. What would have taken hours of wrenching and thousands of dollars in mods was achieved for under $500 and 5 minutes...

My new Ram has the 5.7 Hemi and 3.55 gears. I've added a K&N filter and modified exhaust. I went camping last weekend and drove 80 miles on rural 2-lane roads and averaged 20.4mpg with the AC on.

I've yet to add a tune, as I am happy with the performance and mileage, but would definitely consider one.

If you buy a tuner and download a custom tune, it will replace whatever was done to your truck previously. With my Economy tune in the Mustang, my best mpg average running 87 octane fuel was 27mpg; 2mpg better than stock.
 
#6 ·
Been a while since last check in.
Did the following and got these results. Still pretty unhappy!

I had been running 87 octane with 10% ethanol. City 10-10.5 mpg
Checked book, 87 is okay, but 89 recommended.

20 inch tires were under inflated. Recommended 65 psi, but I'm not hauling anything. Raised from 28 psi to 50 psi. Rides like crap and on the highway with 89 octane 10% ethanol still only got 11.88 mpg.

Found 93 octane ethanol free gas in MS, and combined mileage was 13.8 mpg, highway (driving the speed limit), 14.97 mpg.

That's a lot of gas money for that small gain!

I really want my old 5.9L, 360 back. This 5.7 runs like a scalded dog, but it's breaking my back to feed it!

Pretty disgusted!
 
#7 ·
Been a while since last check in.

Did the following and got these results. Still pretty unhappy!



I had been running 87 octane with 10% ethanol. City 10-10.5 mpg

Checked book, 87 is okay, but 89 recommended.



20 inch tires were under inflated. Recommended 65 psi, but I'm not hauling anything. Raised from 28 psi to 50 psi. Rides like crap and on the highway with 89 octane 10% ethanol still only got 11.88 mpg.



Found 93 octane ethanol free gas in MS, and combined mileage was 13.8 mpg, highway (driving the speed limit), 14.97 mpg.



That's a lot of gas money for that small gain!



I really want my old 5.9L, 360 back. This 5.7 runs like a scalded dog, but it's breaking my back to feed it!



Pretty disgusted!

You're only getting 10.5 at best in the city and barely 12 on the highway?

Either ur getting some bad gas or you got somethin else goin on...

Before I added my CAI, exhaust and programmer, I was gettin around 12.5 in the city and about 13.5 to 14 on the highway. That was all on 89.

I only ran 87 in it like, once or twice but, the first day I bought it, I noticed right away in the owner's manual about it preferring 89 for best results so that's all I ever really ran in it.

Do you have a 3/4 ton or something cuz, the recommend tire pressure in my halfton is 35... I don't run them at 35 cuz 35 seems too much for the rears and not enough on the fronts. I run 45 in the front and 30 in the back. Still rides about like a Dodge but not like a tank.
 
#12 ·
You either have something wrong with your truck or you drive it hard all the time. Even if I drive mine hard I still get over 19 mpg. Drive it easy and 22 is very achievable. This is on 22's and 3.92 gears also.
 
#13 ·
It's a 1500, with 20's. The tire calls for 65 psi, the book calls for 65 psi with the 20's. Since mileage didn't improve with higher pressures as expected, I've lowered back to 35psi.

Gas mileage is miles divided by gallons. Just like always.

This is a 4X4 and sits higher than most, but I still don't see how mileage can be this bad. I do not drive hard. In fact, all this testing has been within speed limits and taking care not to accelerate hard, etc.
 
#17 ·
My stock 2014 2500 CC 4x4 with 6.4 Hemi gets an avg 16.6 mpg with a lifetime avg 15.5 mpg combined rural/in town.

Wow, even with that much bigger Hemi you're getting MPG numbers like that?

Impressive.

I'm still curious what all they did in the newer 4th-gen 5.7's to squeeze upwards of 20 miles per gallon out of them. Even when I try to drive my 3rd-gen with ease and respect, I still can't muster any more than 15 out on the highway.

Guess I'm just gonna hafta start runnin' 87 in it and whip out the ole Trinity and reprogram the computer to the MPG booster tune. Now that 91 has climbed above three bucks a gallon, not in the mood to spend 70 bucks at the pump!
 
#18 ·
i get about 18-19 with 20's and 4.10 gears running about 75mph..... and i get an average of 14-15 back and forth to work in traffic.
 
#20 · (Edited)
Correct me if I'm wrong, but... If you have taller tires don't you need to go into the PCM and change your tire size? Otherwise your speedo and odometer will be off, thus changing your mpg calculations also.

One thing that everyone always glosses over... The definition of "city driving". In the Chicago metro area, there is literally a stop sign/light every two blocks. So my "city mileage is about 11-12 with my '05 2wd 4.10 gears.. When I moved out to the suburbs where you could drive 3/4ths of a mile (or more) between stops. My "city mileage" went up to 13-14. ...and "highway miles" will depend upon terrain also. ...Illinois is flat whereas somewhere else isn't.

What gears does that have with those tires? Like someone said, air filter, throttle body cleaning and spark plugs do wonders.

Good luck!
 
#21 ·
Correct me if I'm wrong, but... If you have taller tires don't you need to go into the PCM and change your tire size? Otherwise your speedo and odometer will be off, thus changing your mpg calculations also.
You're exactly right, if you have taller tires with no speedo calibration for them, you won't be racking up as many miles as you should be because taller tires actually rotate slower at the same vehicle speed as shorter tires would. Think of the last time you saw a tractor in motion and how the short front tires were turning much, much faster than the way taller back ones were.

So if you take that into consideration, your fuel mileage average will be less because you aren't showing the actual miles you drove for the same amount of fuel you refilled with.

I'm not going to break out the slide rule and scientific calculator to figure it out but, on an older 1998 Ram I once had, it came stock with 245/75/16's on it and when I bought it, it had 285's on it and, one night I found out just how off my speedometer was at 70 miles an hour...lol. A Colorado Highway patrolman said I was doing 77...lol.

My mileage came up quite a bit after I recalibrated with one those Superlift speed sensor calibrator modules. Don't ask me how much, that was a long time ago and I have long since forgotten....lol.

Another thing, believe it or not, having an inaccurate speedometer affects how your engine runs, too. Among all the other things like, altitude, air density, air temp, throttle position, vehicle speed also is one of those things the ECM needs to know to properly run the engine at the correct timing advance, spark advance and air/fuel mixture and, if your engine's brain thinks your going slower than you actually are, that can affect mileage as well.
One thing that everyone always glosses over... The definition of "city driving". In the Chicago metro area, there is literally a stop sign/light every two blocks. So my "city mileage is about 11-12 with my '05 2wd 4.10 gears.. When I moved out to the suburbs where you could drive 3/4ths of a mile (or more) between stops. My "city mileage" went up to 13-14. ...and "highway miles" will depend upon terrain also. ...Illinois is flat whereas somewhere else isn't.
Good point.
What gears does that have with those tires? Like someone said, air filter, throttle body cleaning and spark plugs do wonders.

Good luck!
Depending on what size tires he has, regearing the diff(s) won't really matter unless you go like, 3 or 4 sizes bigger than stock.
 
#22 ·
Define stock height. This is the factory setup. Is it higher than most?

With my last two Rams, taller tires made it sluggish and slowed the speedo about 10%. Taller tires screwed with transmission shifting and made the transmission spend a lot of time in pre converter lock-up mode and while bouncing in and out of OD.
None of those things are happening now. The speedo is off about 2-3 %, but nothing major.

Conversations with others who have trucks configured like mine don't seem to bear your comments out.

Now, that said, I don't put a lot of miles on this truck. Just over 3k since January. The truck came to me with a fresh oil change, from a Toyota/GMC dealer. I was never told what oil was used. I just had oil changed and filled with full synthetic 5w20. Odometer and fuel gauge may be showing some city driving improvement, but still under 100 miles since fill up. Will know more this weekend.
 
#23 ·
stock height is anything other then what rolled off the factory floor. some times pictures can be deceiving, but theres not way your truck is stock. theres way too much wheel gap. what size tires are those? can you take a measurement from the ground to the bottom of the fender?

also, comparing your old rams to these new trucks is apples to oranges. these trucks make way more power, have more gears and overall better transmissions. larger tires take less of an impact on drive ability.
 
#24 ·
I can drive by any Dodge dealer and buy any one of several new 4x4s outfitted just like mine. Now tell me again about factory stock. Me thinks you need to recalibrate your logic and your argument.

If you don't have an answer, its okay to say so, or just not answer.
 
#26 ·
why dont you post up your tire size and how high the bottom of your fenders are from the ground like i asked? like i said, its possible pictures can be deceiving. prove me wrong and i have no problem admitting it.

im trying to help you here, like everyone else is, but you seem to ignore the advice given and refute possible reasons. at the end of the day the fact that your truck is getting poor mileage isnt affecting my wallet. if you want to dismiss what im telling you, thats your choice. good luck.
 
#25 ·
Your truck does look rather tall both in the back and the front. Plus it sits level. Factory trucks don't sit level, primarily because of what they were designed to do. They're supposed to sit taller in the rear so that whenever you load the bed down or hook on to a heavy trailer, the back will squat level as opposed to squatting the ground if it were already level before.

Again, as was previously asked, unless I missed it somewhere, what size tires are those you have? I'm not sure on those Gen-4 Rams but on the Gen-3 Rams such as mine, the stock tire size on 20" rims is 275/60/20, which is basically a 33" tall tire.
 
#29 ·
Tires are little oversized. 135/12.00/20. Side by side with other factory setups, I just don't see a difference in level.

I know the issues taller tires made on other trucks. Physics is physics. Mechanics is mechanics.

Taller tires screwed up performance and shifting. Shorter tires yeilded more power but mileage really didn't change.

That's not the only thing happening here.
 
#30 ·
Tires are little oversized. 135/12.00/20.
I'm assuming you're saying you have 35x12's? If so, yer right, going from a 33 to a 35 really isn't all that much of a jump but, without speedo correction, it makes more of an effect than you think. These aren't old, 80's model pickups where it don't really matter what you do.
Side by side with other factory setups, I just don't see a difference in level.
Land vehicle Vehicle Car Motor vehicle Tire

Look at mine. I know it's a Gen-3 and yours is a Gen-4, but, look at the gap in the wheel wells. It's much less than yours and notice how it's lower in the front. And that's with stock 33's. Plus, it's a four-wheel drive, too... I don't know if yours is, if it is, I'm not saying it is or isn't, just simply saying that yours sits a great deal taller than mine and it's ride height and tire size is completely stock.
 
#31 ·
Honestly, from what I see, your mpg seem about right. It's lifted with 35s. You mentioned the tire says 65 psi, so I'm thinking load E tires which are heavy as shit. Add to that the height and yeah, I could see 10mpg around town, especially if the speedo has not been updated. Check your gearing. Worse yet, you could have 3.21 gears which are only going to make it worse.

Sadly, to reach these crazy high mpg numbers out of a 5.7, the factory has to have everything just so. Change any of that and it all goes to shit. I figure if I had this truck back in 1980 with a motor this big I would never break 10mpg, ever. Not even downhill with a tailwind. Our days of "tuning" are over. Watch the youngsters at the track meets now and all they do is plug in a laptop and create crazy numbers with keystrokes.
 
#32 ·
Honestly, from what I see, your mpg seem about right. It's lifted with 35s. You mentioned the tire says 65 psi, so I'm thinking load E tires which are heavy as shit.
Yeah, I don't know why I didn't mention it before but, just because the tire has a max pressure of 65, that doesn't mean they have to be ran at that pressure. All that is, is just the max pressure cold that the tire can be inflated to. My Cooper's say 44 on the sidewalls but, I only run 35 in them.

If they were E range tires, their max pressure would be around 80 psi. He probly has load range D tires since the max pressure is 65, which makes better sense as bigger tires usually come in an 8 ply which yeah, are pretty heavy rubber especially in a 35.

Check your gearing. Worse yet, you could have 3.21 gears which are only going to make it worse.
Yeah, even with a corrected speedo, taller tires is gonna raise the final drive ratio. It may have either 3.92's, 3.73's or 3.21's in the diffs but, for example, let's say he does have 3.21's in the diffs, them 35's are gonna make the final drive ratio be like he has 2.90's all the sudden....lol.
 
#35 ·
Some of the milage figures people are posting here look a little bogus to me (19mpg with 4.10's going 75 mph) that one really got me. I don't understand why anyone would buy a full size 4500lbs truck with a semi and expect gas milage. Buy an ugly little foreign car if you want milage.
My SCSB Hemi with 3.92 gear gets about 15mpg going 80 mph on a good day with the stock tune.
 
#36 ·
Some of the milage figures people are posting here look a little bogus to me (19mpg with 4.10's going 75 mph) that one really got me.
I've never driven one, nor do I know anyone that has one but, they claim those newer, less than 4 to 5 year old Hemis are getting upwards of 20 miles to the gallon. If this is true, I don't know what Dodge did to accomplish this but my '08 Hemi will ever see that kind of mileage...lol.
I don't understand why anyone would buy a full size 4500lbs truck with a semi and expect gas milage. Buy an ugly little foreign car if you want milage.
True, and I agree with you for the most part but, trying to get a little more miles out of a tank of gas is nothing wrong by any means. Gas prices ain't what they used to be and when gas is expensive, unlike what it is now in most parts of the country, it's hard to afford fillups at anything less than 15 MPG...lol.

Besides, you can't be cool in a typical little foreign car!....lol. But, I don't wanna break the bank, either....

With that said, at least with me, I don't expect to see 20 MPG numbers oughtta my truck. It would be nice but as I said, I don't expect it so, I don't worry about it.
SCSB Hemi with 3.92 gear gets about 15mpg going 80 mph on a good day with the stock tune.
Mine with the stock tune never saw that. That was even with the MDS working every now and then.

With a Diablo Sport Trinity in the 91 performance tune and the MDS turned off, I average around 12.5-13.5, but that's around town. I think out on the highway I may see around 14 but that's very rarely...lol
 
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