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Diesel Fuel Economy and chips

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  • I've narrowed it down to a early 04 2500 4x4 QC short box or a 05 2500 4x4 QC short box, both are pretty much identicle with options, both are SLT, tow, single cd, power every thing etc.

    They both have about 12000 miles on them and are in great shape, the 04 is $29800, the 05 is $31700.

    I like the color of the 05 ( more warranty left on it)but I have heard that the early 04s have the older engine and gets better fuel mileage. I've heard the 05s only get about 14-16 empty, and 12-14 loaded(depending on what you are towing of course). I've also heard the 02-early 04 engine will get 20+ empty and 16mpg towing.

    Is this true???

    Can you add the locking lugs and Quadzilla chip to the 05 and get the fuel mileage compareable to the early 04??

    Thanks for any help, I've never owned a diesel and need some help.

    Any issues I should be aware of with either engine??
  • One last question...which one do you think is the better buy???
  • I've narrowed it down to a early 04 2500 4x4 QC short box or a 05 2500 4x4 QC short box, both are pretty much identicle with options, both are SLT, tow, single cd, power every thing etc.

    They both have about 12000 miles on them and are in great shape, the 04 is $29800, the 05 is $31700.

    I like the color of the 05 ( more warranty left on it)but I have heard that the early 04s have the older engine and gets better fuel mileage. I've heard the 05s only get about 14-16 empty, and 12-14 loaded(depending on what you are towing of course). I've also heard the 02-early 04 engine will get 20+ empty and 16mpg towing.

    Is this true???

    Can you add the locking lugs and Quadzilla chip to the 05 and get the fuel mileage compareable to the early 04??

    Thanks for any help, I've never owned a diesel and need some help.

    Any issues I should be aware of with either engine??
  • jim314jim314 Posts: 491
    The 315s are 8.7% larger in diamater and in circumference than than the stock tires. So unless you reprogrammed your odometer and speedometer and computer, then you are travelling 8.7% farther and 8.7% faster than your odo and speedo indicate.

    Therefore your true mpg values would be 1.087 times what you have reported. So, e.g. 19.0 mpg from an uncorrected odo reading would actually be 20.7 mpg.

    And if your speedomoter read 70 mph you were actually going 76 mph. The power required to overcome air resistance rises strongly with increasing speed (NASA) so the engine was having to put out more power at the wheels which would act to decrease true mpg. It is true that these larger tires will decrease engine rpms by 8.7% at the same true speed and this could improve fuel economy especially on level ground, lightly loaded, but it almost certainly would not balance out the increased air resistance, and it would definitely hurt hill climbing performance and pulling force in any gear. Also these wide off-road tires are going to have large rolling resistance compared to tires designed for pavement.

    If you are really interested in getting maximum mpg then think about the tires you replace these with, but don't go overboard on getting low rolling resistance tires that don't have good traction, especially on wet roads. It does rain in the Texas Hill Country occassionally, doesn't it? You don't want to slide off the road into a gulley some rainy night when a deer jumps out in front of you. Wouldn't be good for your truck, for you, and maybe wouldn't even save the deer.

    Calculations:
    Dia 315/70-17 = (315mm)(1in/25.4mm)(0.7)(2) + 17in = 34.36in
    Dia 265/70-17 = (265)(1/25.4)((0.7)(2) +17 = 31.61 in

    34.36/31.61 = 1.087.
  • dwddwd Posts: 4
    Your pretty close with your calculation of 1.087. I recently went on a 300 mile cruise down the interstate. I returned the truck to it's stock program and measured my odometer reading with the mile markers on the side of the road. After the trip I calculated that to get the correct odometer reading, speedometer etc. I need to multiply by 1.076, exciting stuff.
    I live and work on a ranch in the hillcountry, it's prety rocky and rough. The tires are great around the ranch but I don't think the reduced mileage is worth it. When I replace the tires I will change tire size not the type of tire. I have to have an off road tire for the ranch and getting to it, I live about 12 miles down a gravel road. By the way, rain would be wonderful we are in the 2nd year of a drought and my ranch and cows don't think it's funny anymore.
    As far as the deer go, if I were a deer i wouldn't count on me swerving. I've lost a few friends that way and my ranch hand bumper would not be kind to bambi.
    Thanks,
    dwd
  • dr_cdr_c Posts: 1
    Does anyone know why the 06 PS Diesels are getting worse fuel mileage than any of the previous PS Diesels?

    I have a 06 SB F350 4WD 6.0 Diesel that will barely get better than 12 mpg. I have a friend with the same truck and the same issue. I had an 02 LB F350 4W PS Diesel that consistently got 16- 18 mpg. Both are/were chipped up and have/had tons of hp. I just think I should get a lot more mpg with this new truck.
  • banshee1banshee1 Posts: 12
    The reason we take longer to shut down isn't because it's a diesel, it's because we have a turbocharger that needs to have oil running over the bearings for a minute or so to keep them from "coking" or oil baking on the bearings and after that happens a few times, the turbo doesn't spin and your'e out a couple o' thousand bucks. But the guys who leave them running for 15 or 20 minutes plus is wasteful and puts your motor in the severe usage catagory.
  • banshee1banshee1 Posts: 12
    The answer is simple,Ford,Dodge,Chevy,take your pick. Or,Ford,toughest truck,weakest motor to date.Chevy,powerful motor,quiet interior,weak chassis.Dodge,nice truck,for some reason,everyone likes to put twin turbos and transmissions in them. If your'e not brand loyal,you should take everyone for a test drive and see which one you really like.I bought my 05' King Ranch F-350 without test driving it because I didn't need to. I'm a Ford guy.Just make sure you give your new truck the three STANDARD modifications;intake,exhaust,programmer.You will be happy and your truck will be happy.
  • bsouthbsouth Posts: 1
    I've got a 2006 3500 Mega Cab Dually, 4x4 and my mileage is very similar to yours... They told me it would start creeping up at 5000 miles (I have about 6500 on it now), but it's actually going down.. about 14 on the highway (70-75mph) and about 11 towing (approx 13,000lb horse trailer loaded, 70-75 mph)..

    I've heard the 20mpg stories too, but I'm not even close!!!
  • I appreciate your response to my idling question but I was talking about the 15 - 20 minutes types. However, could you shed a bit more light on the comment about bearings needing oil for a few minutes. I just purchased a new DOdge and do not want to do anything that might cause problems. Plus, there is so much conflicitng info out there and you sound as if you know what you are talking about. Thanks a million.
  • I'm a novice with heavy duty trucks. Will be putting on low miles (8-10k / year), pulling a 2 horse trailer occassionally. Want a reliable truck, like the idea of better fuel economy (is 20 mpg realistic?) What after market work is routinely needed (chip, intake etc,,) and how much do these usually run? I've driven mostly ford/chevy light duty in the past, but the RAM seems to be the users choice in heavy duty. Any help much appreciated
  • winter2winter2 Posts: 1,796
    Maybe I can help. I have a 2005 Jeep Liberty Limited CRD. Yes it has a diesel engine and it is turbocharged.

    There are two good reasons why you idle any turbocharged engine for several minutes after running down the road.

    Turbochargers spin at incredibly fast speeds of 70K to 100K or even faster. Idling lets the turbocharger spin down and also allows oil to run over the bearing any cool it. Remember that exhaust heat is transferred via the blades/fan to the shaft and bearing(s). In most cases the bearing is oil cooled while in other instances, it is both oil and water cooled.

    One trick to avoid coking the bearing in the turbocharger is to use a synthetic oil. There are plenty of good ones out there that are readily available. It is difficult if not almost impossible to coke a good quality synthetic motor oil. Do not start using a synthetic oil in your diesel until about 8K to 10K miles. At that point the engine should be broken in. Using a synthetic before that time could prevent the rings from setting up properly.
  • jim314jim314 Posts: 491
    I've seen in various authoritative sources that the exhaust temperatures in diesels are much lower than in gasoline engines (perhaps 200 deg F lower or even more). Therefore it would seem to me that the turbocharger bearings in diesels should be less likely to experience heat mediated oil breakdown than gasoline engines, although I cannot remember if I have seen this explicitly stated.

    Nevertheless I would definitely use full synthetic oil in any turbocharged vehicle and I would let it idle for a short time (about 1 to 2 min) before shutdown after operation at high power. I do this even with naturally aspirated (i.e. non-turbocharged) gasoline engines, say when pulling into a rest stop on the interstate. I have always heard this allows the valves to cool. I even do this with my Honda aircooled engine lawnmower in which I use Mobile1 10W-30.

    Note also that a few years back Toyota redesigned the heads on some of its premium engines to increase HP and fuel economy, with the undesired result that oil temperature in the redesigned heads increased significantly. There were a large number of engine failures due to overheating of the oil in the head leading to "sludging". Toyota did not require full synthetic oil, and I'm under the impression that all the failures occurred with conventional oil.

    In about 1998 I switched to Mobile1 in my wife's 1996 Volvo 850 wagon non-turbo, which unfortunately was totalled in 2004 in a rollover. She replaced it with 2004 Volvo V70 non-turbo. After break-in of 4000 miles of short trips, I had the original oil fill changed to Mobile1 10W-30, and have used that since. I have the oil and filter changed at the recommended 7500 mi intervals (no charge from Volvo dealer for first 3 or 4 years or 60kmi or 80kmi), but I must supply the 6 qts of Mobile1. Castrol syntec would be free from the dealer and would probably work perfectly, but I pay the extra $40 for the Mobile1. When the power train warranty is over, I intend to go to 10,000 or even 15,000 mi interval or 1 year with Mobile1 10W-30 extended service oil.
  • winter2winter2 Posts: 1,796
    With exhaust temperatures as high as they are, I feel that the few hundred degrees difference does not matter. Hot is hot and if you are not careful, you can coke the oil and destroy the bearing in the turbocharger.

    The problem with the Toyota sludging situation was not only a head design issue but also the way blowby gases were circulated through the engine. As I have read, Toyota redesigned the way the blowby gases were circulated.

    I see you and I agree on the use of synthetic lubricants. I do not use Mobil 1 for a couple of reasons. One of them is political and personnel. The other reason is that their oils generally do poorly on the Noack vaporization tests and end up with double digit losses during the tests. I prefer Amsoil products or RedLine products. Yes, they are more money but they are also better oils with low single digit vaporization losses. Their oils for diesel engines are outstanding and with as much blowby as a diesel produces, the CCV system on my Jeep Liberty CRD is actually quite clean.
  • I am fairly happy to let ya know my new 2006 6.0 ltr F350 crew 4x4 got 21 mpg on the hwy at 110km/ph (66mph) with the tailgate down and everything stock. I have 22,000 km (13,200miles) on the truck and travelled 3 hrs. However I must confess to a slight tailwind less than 10km(6 mph gusts). I love my new truck but what a dog off the line. Still used to gassers but will never go back.
  • jim314jim314 Posts: 491
    I saw a mythbusters episode that purported to bust the story that the fuel economy of a pickup truck was higher with the tailgate down. They tested this directly and then put the truck in a windtunnel with smoke visualization and showed that the airflow was over the tailgate in the up position.

    Try it again with the tailgate up and see if you detect any difference.
  • I am going to buy a new 06 Dodge Diesel pickup. I am interested if anyone can tell me the difference (if any) in the fuel economy between the Automatic Transmission and the 6 speed manual. All of the other Dodge pickups I have owned have been 5 or 6 speed. Thanks for the Help.
  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,496
    If the trucks are othjerwise identical, the automatic will give you better highway mileage, because its overdrive gear is substanitally taller - 0.69:1 for the automatic, 0.79:1 for the 6-speed manual. In town or fully loaded, they'll be pretty close.

    kcram - Pickups Host

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • gordgord Posts: 5
    My 04 4wd Crewcab Ram Diesel with 4 spd automatic has shift points for 3rd at about 43 mph and to OD at 50 mph. With the 5 or 6 spd manual, you may be able to get into a higher gear sooner than 43 in town and maybe see better milage than I do having to spend much of the time in 2nd and 3rd. I would think that, depending how you drive (mostly city or highway), would make the difference as the other reply indicated.
  • I wont be making that trip again for a while but when i do i will leave it up. However i did have my tailgate up during a bit of a storm and when i got home my tailgate had two big dirt circles on the inside showing me where the wind and rain was ending up. My speeds were much lower due to weather which would be a cause of the settling. I like mythbusters and wished i would have seen that one. But I will try that again.
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