dodge cummins questions....

[maxwell]

on the weekend we took my friends new to him 2004 cummins to the mountains. our cruising speed was about 120km/h. hauling 3 sleds 3 people and a trailer we got about 650km/tank. the truck was raeding 15.1mpg @ 2100rpm

my issue is that it seemed to me the truck did not need to be at 2100rpm to get the power to push us at 120km/h. what kind of modifications can be done to lower the cruising rpm for better economy? all i can think of is to run a larger tire?

also the truck would hold speed going up hill no problem at 110-120km/h. but you could put the pedal to the floor and it would not shift down? seems to me on the powerstroke if you are cruising and need to speed up it will shift down and pull away. is this something that a exhaust/intake/programmer would make up for on a cummins?

 

[pete_ame]

What gearing does your friends truck have? My dodge has 4.10's which is too high for lots of highway driving. It howls pretty good at anything above 110.

 

[maxwell]

ill look into that. i just figured all the 3500s had the same gearing...just seems to be reving to high at highway speed. but i really dont know so i cant say

 

[Metalfusion]

on the weekend we took my friends new to him 2004 cummins to the mountains. our cruising speed was about 120km/h. hauling 3 sleds 3 people and a trailer we got about 650km/tank. the truck was raeding 15.1mpg @ 2100rpm

my issue is that it seemed to me the truck did not need to be at 2100rpm to get the power to push us at 120km/h. what kind of modifications can be done to lower the cruising rpm for better economy? all i can think of is to run a larger tire?

also the truck would hold speed going up hill no problem at 110-120km/h. but you could put the pedal to the floor and it would not shift down? seems to me on the powerstroke if you are cruising and need to speed up it will shift down and pull away. is this something that a exhaust/intake/programmer would make up for on a cummins?

Taller tires would lower your hiway RPM a little but not as much as gears would. A 3:73 gear with a 285-315 tire on the 3500 runs real nice on the hiway. A programmer would most deffinently help with the Cummins. It becomes a totally different truck. A cold air intake kit will help also.

 

[mudboy]

Actually with what you were towing my 2005 dodge 3500 runs at about the same rpm. I have an edge ez programmer cat back exhaust and a s&b cold air intake plus toyo 295 tiresIf you slow down to 110 / 100 your rpm would of dropped down to about 1700 / 1800. I find that 2100 is the sweet spot on my truck

 

[RMK Junky]

5.9L Cummins Power Output Timeline

A diesel best performs in its torque curve. That's the sweet spot.

 

[booster]

on the weekend we took my friends new to him 2004 cummins to the mountains. our cruising speed was about 120km/h. hauling 3 sleds 3 people and a trailer we got about 650km/tank. the truck was raeding 15.1mpg @ 2100rpm

my issue is that it seemed to me the truck did not need to be at 2100rpm to get the power to push us at 120km/h. what kind of modifications can be done to lower the cruising rpm for better economy? all i can think of is to run a larger tire?

also the truck would hold speed going up hill no problem at 110-120km/h. but you could put the pedal to the floor and it would not shift down? seems to me on the powerstroke if you are cruising and need to speed up it will shift down and pull away. is this something that a exhaust/intake/programmer would make up for on a cummins?

If you want to spend some money throw in taller gears That will get you further running less rpm. As for the shifting get a decent programmer like the smarty or wait a couple of months and efi live will have a new one out for the cummins. A programmer will make firmer shifts and increase line pressures in your tranny.
As for running a larger tire it will actually hurt your milage. Unless you run something really hard and not agressive which isnt good for going to the mountains.

 

[albertasummitx]

with my 01 ,the sweet spot for fuel is 1500-1800 which is 95-100km /hr ,that being said i have s&b cold air intake ,chip,b&d turbo 140hp inj .i was getting 24mpg pulling 28' holiday trailer before i changed injectors . at 110 they seem to be around the 2000-2100 rpm ,but you cant beat a cummins ,to bad they come wrapped in a dodge.

 

[maxwell]

there was an article in deisel tech mag that larger tires will increase your milage...?

 

[maxwell]

i also wanted to ask about programmers and exhaust sytems...just wondering how dealers take to this as far as warranty is concerned. i have heard some will allow intakes and exhaust systems? and proggrammers are a nono. but when it goes in for service it can be programmed back to stock.? which programmers allow you to do this.

 

[Summitric]

i also wanted to ask about programmers and exhaust sytems...just wondering how dealers take to this as far as warranty is concerned. I have heard some will allow intakes and exhaust systems? And proggrammers are a nono. But when it goes in for service it can be programmed back to stock.? Which programmers allow you to do this.

if you get along with your dealer there will never be a problem..... I have oversize tires and 3" lift on my '06 and had ball joints and steering components replaced under warranty...... I also had 5" exhaust, stacked chips, afe intake bladerunner and cold air intake system....... Service manager said no problemo, as long as nothing was caused by these parts......

 

[NM]

If it's getting 650 k to a tank cruising at 120 with 3 sleds and not losing any speed on the hills, then I would say leave it alone. Most Ford guys would be doing backflips and cartwheels if they could get 650 k per tank. You start adding power and it will wear other parts much faster (tranny for sure). The truck likely has no warranty and I'm sure the dude doesn't need a bunch of costly repairs. I would say 285 tires would be ok, but recalibrate the speedo for better shifting.

 

[Summitric]

if it's getting 650 k to a tank cruising at 120 with 3 sleds and not losing any speed on the hills, then i would say leave it alone. Most ford guys would be doing backflips and cartwheels if they could get 650 k per tank. You start adding power and it will wear other parts much faster (tranny for sure). The truck likely has no warranty and i'm sure the dude doesn't need a bunch of costly repairs. I would say 285 tires would be ok, but recalibrate the speedo for better shifting.

yup, i agree.........don't touch it........don't fix it, if it aint broke!!!!

 

[maxwell]

yeah but thats boring.......a slight street 50Hp exhaust and intake cant hurt to much...

 

[Summitric]

yeah but thats boring.......a slight street 50hp exhaust and intake cant hurt to much...

i just finished taking the 5" exhaust and then the 4" magnaflow muffler off and went to a quiet muffler because there was too much resonance noise when pulling the big trailers up hills and under loads....too loud when passengers in the back seat.....just my 2 cents

 

[albertasummitx]

as far as intakes,s&b and a few others offer to you that if the dealer refuses warranty ,to take them to court and they will pay your repair bill.as far as chips and exhaust summit ric is right -you need a good dealer. you would think that a larger exhaust which is lowering your egt's would be welcomed.but with the new dpf's they need the heat to burn off all the soot collected.

 

[mach123]

Maxwell, we are going to golden from red deer with 3 guys and 3/4 sleds with a 5.9 cummins and I will let you know how we do on fuel.

 

[Cyle]

Good dealers in Alberta? Good luck..... I bought my 04 two years ago will never see the dealer again, I will just replace anything myself, Chrysler is useless.

As far as MPG that is kinda low for a stock truck. That is the same MPG I get with 6" lift and 37" tires with 3 sleds also. A stock truck you should see a good 800 to a tank on the highway like nothing even in the winter. Some trucks do get better mileage though, my dads old 05 got over 1100km on a tank, and still only took about 120L.

Also, as far as MPG don't trust the overhead it is just a lie o meter. Bigger tires will help to an extend if they aren't to wide and something like an AT. Lower RPM's help but bigger rolling resistance can take it away. The best thing for MPG is just to slow down.

As far as mods, the truck already has 4" turbo back, if you want sound you can just get rid of the cat or muffler (depending if it's a early of late model 04 early ones had no cat). Unless your going for big HP like 600+ 5" exhaust is useless. Intake won't see much either, just sounds better. Programmers don't really help MPG, if you do all 3 mods you might see 1 MPG better depending on driving habits.

As far as crusing speed if it's a light load anything between 1700-2200 is good, but if your pulling anything you want to keep the rpm's over 2000 or you'll lug a bit on hills.

 

[Summitric]

MY '06 WITH A 28FOOT SLED TRAILER AND 5 SLEDS, AND A 250L FUEL CELL AND ALL OUR GEAR ETC.... MY LITTLE RED DODGE MEGACAB 3500 4X4 5.9L TD GETS ABOUT 600KM TO THE TANK, AVERAGING ABOUT 120 TO 130KPH..... HAVE GONE 180KPH PULLING THE BIG TRAILERS!!! SHHHHHH, DON'T TELL NO ONE. I CAN GET ABOUT 1000KM EMPTY AT 130KPH.............THE BLUE OVAL BOYS AND BOWTIE BOYS DON'T LIKE WHEN US DODGES RAM IT!!!!

 

[DRD]

Cyle, I have a tough time believing that your dad got over 25 MPG with a full size diesel pickup, Is your dad driving a jetta?