# 2004 dodge ram 2500 5.9 cummins ?



## gmcplowtruck

i recently picked up a 2004 dodge ram 2500 4x4 quad cab short bed diesel truck with all the bells and whistles love the truck has 251000 miles on it paid $8500 and had to put tranny tires and universals on it truck gets 18 mpg around town and 23-24 mpg on highway empty well pulled out quikly the oter day and truck got uder got under to find out exhaust was rusted in front of muffler and snaped off my question am i better off strait piping the truck or putting muffler back on which gives me better mpg hp what do you guys think all comments apreciated


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## BigDave12768

Only problem with straight piping it is you will lose back pressure. It will also be louder. So without back pressure you will lose low end power. You can get mufflers and complete systems fairly cheap.


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## gmcplowtruck

ok so im better off putting the muffler back on i really thoght it gave me more power without thanks forthe advice


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## BigDave12768

Stock trucks with stock turbo's need the muffler for back pressure. If you went straight pipe with no back pressure your Turbo would take longer to spool up. This is called Turbo lag. This is where you would feel a loss in power. Waiting for the turbo to spool up. So as the tranny goes through gears and drops Rpm's every gear. Your turbo would be late in helping. 

This theory goes out the window if you have a heavily modded truck with an over sized turbo and such. But since we are talking stock aplication here and not some 500+hp truck. I would put a mufler back on. Plus the droan of a straight pipe would be so annoying. But thats just my opinion

And if you getting your 18mpg on a 04 you have a 305hp motor? with 3.73? Check vin for 8th digit 6=305hp C=325hp. The 305hp motor has a smaller turbo than 325hp produced after 1-1-04. So I am sure you are not winning any races off the line. This arguement has been beaten to death online.


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## gmcplowtruck

it is a 305 but i ot the truck for a great price and i origanally was using an 01 dodge gasser that was geting 5 mpg plowing and had no power to carry the salt i carry i was looking at the truck and im gonna see if the exhaust shop can weld the seem it broke clean because the system is in really good shape exept for that one spot 
thanks for your help


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## got-h2o

Wrong on the backpressure thing, and mufflers only quiet them, they really have nothing to do with backpressure......pipe size does. Turbo'd vehicles do NOT require back pressure. There have been countless discussions, dyno tests, etc to prove this. Although you may think you feel power loss, its not the case. You could essentially run a wide open turbo and have no adverse effects (aside from potentially lighting the truck on fire!). The wastegate controls exhaust output from boost, not backpressure. Boost is produced under a load. You could floor it in neutral and barely produce boost, barely opening the gate. VVT's are different, but use the same principal. You want it to breathe, its the best thing for a turbo. Breathing better means lower EGT's, lower EGT's means more power, and more efficiant fuel consumption.

Jump on me all you want, I've got 3,400 posts, 4 years on a diesel forum, and have owned 8 modern diesels to back this up. I have a 5" straight piped single stack on one of my trucks and its no slower than my other with stock exhaust.


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## exmark1

got-h2o;790261 said:


> Wrong on the backpressure thing, and mufflers only quiet them, they really have nothing to do with backpressure......pipe size does. Turbo'd vehicles do NOT require back pressure. There have been countless discussions, dyno tests, etc to prove this. Although you may think you feel power loss, its not the case. You could essentially run a wide open turbo and have no adverse effects (aside from potentially lighting the truck on fire!). The wastegate controls exhaust output from boost, not backpressure. Boost is produced under a load. You could floor it in neutral and barely produce boost, barely opening the gate. VVT's are different, but use the same principal. You want it to breathe, its the best thing for a turbo. Breathing better means lower EGT's, lower EGT's means more power, and more efficiant fuel consumption.
> 
> Jump on me all you want, I've got 3,400 posts, 4 years on a diesel forum, and have owned 8 modern diesels to back this up. I have a 5" straight piped single stack on one of my trucks and its no slower than my other with stock exhaust.


Your dead on! I have a 2003 & 2001 Dodge and a 2000 7.3 Ford all are 4" exhaust straight piped turbo to tail pipe. We have NO issues with turbo lag, back pressure etc... actually helps ALOT with fuel milage as well


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## got-h2o

OH and BTW, that seems like a great deal you got on the truck too. I'd have bought it for that.


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## BigDave12768

Get into a pile once in a driveway and you will never plow that driveway again unless its a free one for a family member


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## basher




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## exmark1

BigDave12768;790279 said:


> Get into a pile once in a driveway and you will never plow that driveway again unless its a free one for a family member


We have plows on all of our trucks, never had a complaint! The plow makes enough noise the way it is


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## cretebaby

*Calling for Camden*

Camden..................Camden.........................Camden

I think you need to post that picture you got for Dave again,


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## got-h2o

Just a little more helpful info real quick too. Headers and backpressure.......PRE-turbo. That's pretty self explanitory. 

Lastly, post-turbo backpressure is going to be caused by the smallest exit point, regardless of where it is in the system. The turbo exhaust exit is a cetrain size, so anything after that will have no negative affects. Once again, larger exhaust is beneficial to lower EGT's. 

I'm not going to argue. Take my posts for what they're worth. I'm only trying to help. I've done my research and clearly understand the physics involved in how a turbo works.


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## basher

got-h2o;790347 said:


> Lastly, post-turbo backpressure is going to be caused by the smallest exit point, regardless of where it is in the system. The turbo exhaust exit is a cetrain size, so anything after that will have no negative affects. Once again, larger exhaust is beneficial to lower EGT's.
> 
> I'm not going to argue. Take my posts for what they're worth. I'm only trying to help. I've done my research and clearly understand the physics involved in how a turbo works.


Yes you do:salute: but I could argue that gas flow restriction due to improper bending of incorrectly specified pipe size of the exhaust _could_ actually produce higher restriction then the turbo exhaust exit, at the cost of performance of course. That would highly unlikely though it quite possibly has been achieved in a Midas shop somewhere.


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## got-h2o

basher;790360 said:


> Yes you do:salute: but I could argue that gas flow restriction due to improper bending of incorrectly specified pipe size of the exhaust _could_ actually produce higher restriction then the turbo exhaust exit, at the cost of performance of course. That would highly unlikely though it quite possibly has been achieved in a Midas shop somewhere.


I agree. The opposite affect would cost performance, namely due to higher temps. Backpressure on turbo'd vehicles does and can exist, but that's not necissarily a good thing. Stock exhaust is typically pretty restrictive. No mandrel bends.


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## M1N1TRK

Yes the more back pressure you have going from the manifold to the turbo will create a faster spool up on the turbo and less lag.

You esentially do not need to run any exhaust tube after the turbo if you dont want to. The only reason they have them is to keep the soot from making a mess under the trucks.

If you look at any after market diesel muffler you will see that it is nothing more then a resonator. I can stick my arm through my muffler from one side to the other with out an issue.

The diameter of the pipe is what you need to be carefull of. A stock diesel truck with horse power up to 400hp is good with a "true" 4 inch system. if you want to go with a 5" system then you need to put out anywhere from 400 to 600 hp and then after that you will need to run a 6 inch or larger.

I will be putting a 5" stack on my truck soon for the reason that i am putting 350hp and 621 ft. pounds down to the wheels right now with only an air intake, intake elbow from the intercooler to the engine and a diablo sport tuner set on extreme. any other mods to the truck and i will not see the power gains that i could with a larger exhaust.

A stack on a pick up is just a glorified straight pipe also since there is no muffler involved with the install. FYI


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## basher

BigDave12768;790426 said:


> could it be that a huge wide open exhaust creates no backs pressure. and not only does back pressure help turbo spool up but it also cools the turbo. .


Not on the duramax


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## nickv13412

Now that this thread has caught my attention, id like some reading material on how backpressure would lead to cooler EGTs. It goes against everything I learned in Thermodynamics I and II. Im gonna agree with the guys saying that a straight pipe will reduce EGTs, unless the pipe is too small and restricts flow too much, or too large to the point where the exhaust flow is turbulent and causes restriction as well. And i dont belong to any diesel forums, I already spend too much time on these plowing ones.


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## gmcplowtruck

thanks guys alot to think about may strait pipe in a year or put exhaust on but got it welded today for $25 so when that breaks ill do something if i put an exhaust on or cold air intake do i have to put extra gauges on the truck


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## JohnnyU

You don't really _need_ gauges as long as you're running stock programming, but as soon as you start making modifications, it's never a bad idea to install gauges in order to monitor your vital engine parameters. I always recommend Exhaust temp, Trans temp, and boost pressure. Fuel pressure (lift pump or rail pressure would both be nice). With those parameters under surveillance, a problem can be quickly spotted, diagnosed and hopefully repaired or have the truck shut down before serious damage occurs.

I'm running EGT, Trans Temp and Boost Pressure on my truck.


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## TGM

muffler not needed. turbo creates enough back pressure. these aren't gas motors guys...


cumminsforum.com
compdiesel.com
tdr1.com
thedieselgarage.com


etc.


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## JDiepstra

Although there is a huge amount of misinformation in this thread, the correct info has come out. Fact is, the exhaust side on the turbo is the restriction point and creates all the backpressure you need. You do not need a muffler for the turbo to spool up properly, but, you do need a muffler if you don't want to wake up all of your customers and their neighbors


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## gmcplowtruck

how long between oil changes in the 5.9 cummins couldent find in owners manuel


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## BigDave12768

book says 7500 if towing and 10k if not. I run Rottella Syn and get it at wally world for 18 a gallon. So buy 3 gallons and then get a mobil 1 filter at parts store. Your good for 10k easy


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## Banksy

I run Rotella Syn too, but use Fleetguard filters all around.


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## gmcplowtruck

sams club has a case of 3 gal of rottella t for like $40 i thought it was 10 k but wasnt sure thanks guys


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## TGM

just make sure you do NOT use fram oil filters! 

the media will break up from diesel fuel after 3000 miles and plug up piston cooling nozzles. maybe they've changed the media after the complaints but i don't trust them.


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## gmcplowtruck

what is better for new exhaust turbo back or cat back found cheap on ebay


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## TGM

turbo back preferably unless they're extremely strict where you live


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## BigDave12768

Depends on what motor you have in truck. If you have the 305hp motor you should get the turbo back if you have the 325hp motor the Cat back will be fine. and you can delete cat if you want. Early 04's had a 3.5 down pipe and exhuast where the 04.5 (325hp) has a 4inch turbo back set up with a cat. The early 04 no cat. So what motor do you have? Whats 8th digit of vin? or build date?


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## gmcplowtruck

8 th digit is a c


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## BigDave12768

ok so you have the 325hp truck. So you have cat. So you can run cat back if you like. You already have a 4 inch Down pipe becuase of the larger turbo in that truck. if you took Cat out for off road use only. Benifits are you would get MPG. Downside would be a fine and failure to get a sticker. Thore are both sides. So you can even straight pipe it without being that loud with CAT in. I personally have the MBRPS cool Duals Cat back. They are only really loud at WOT. No real drone on highway. So keep in mind cheaper is not always better. There are many CTD sites that can give you tons of Advice on a system


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## TGM

fines are very rare but i have heard of them. mine's an early 04 cali 235hp motor that did come with a cat. did...


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## BigDave12768

Oh one other thing you have 04.5 Dodge with a C motor. When you go to Autozone and they ask the motor they actually have the 6 or C option. And if you want to buy a programmer. Its a 04.5


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## BigDave12768

TGM;800557 said:


> fines are very rare but i have heard of them. mine's an early 04 cali 235hp motor that did come with a cat. did...


Oh yeah its pretty much unheard of. But its good to note its illeagel. They never check in MA. But ti think we all the new diesels popping up and bypassing the EGR stuff they may start checking more for stickers. You have rare truck huh. Not many 04 SO's out there.


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## TGM

...especially with a VGT turbo from a 6.7. in all reality, i wouldn't worry about having no cat., especially if you have a muffler on your truck - no one checks. i'd worry about removing a DPF.

i sort of got lucky...traded in my 01 6 speed dually for this in danvers-herb cahmbers, and got this truck. it literally came from cali so at 61k, it had NO rust. now i can stay ahead of it since i'm really anal about keeping my rig in good shape.

you don't go on www.newenglandturbodieselpower.com do you?


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## BigDave12768

TGM;800640 said:


> ...especially with a VGT turbo from a 6.7. in all reality, i wouldn't worry about having no cat., especially if you have a muffler on your truck - no one checks. i'd worry about removing a DPF.
> 
> i sort of got lucky...traded in my 01 6 speed dually for this in danvers-herb cahmbers, and got this truck. it literally came from cali so at 61k, it had NO rust. now i can stay ahead of it since i'm really anal about keeping my rig in good shape.
> 
> you don't go on www.newenglandturbodieselpower.com do you?


No more of a DTR guy. I may look for a new truck this winter. Not sure if I want the 6.7. I like exhuast brake option. Not sure if the 07 5.9 came with it.


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## gmcplowtruck

the exhaust that i found cheap was a mbrp 4 inch aluminized mandrel ben cat back $230 turbo back $250 i talked to a guy with a new 6.7 he said he hated it because the mpg is horrible he said he was getting about 10 mpg from what i hear the 5.9 is still the best


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## BigDave12768

gmcplowtruck;801127 said:


> the exhaust that i found cheap was a mbrp 4 inch aluminized mandrel ben cat back $230 turbo back $250 i talked to a guy with a new 6.7 he said he hated it because the mpg is horrible he said he was getting about 10 mpg from what i hear the 5.9 is still the best


Yeah the early 6.7 had a MPG issue. But there is a flash at dealer that helps it. Well at least thats what I read


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## TGM

BigDave12768;800653 said:


> No more of a DTR guy. I may look for a new truck this winter. Not sure if I want the 6.7. I like exhuast brake option. Not sure if the 07 5.9 came with it.


no, the 5.9 did not have the exhaust brake option. the 6.7s use the turbo as the exhaust brake...at some point i want to rig my turbo up to use that function since i have a variable geometry turbo from a 6.7 in my 5.9.


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## Banksy

305 hp 555 tq here. No cat came on mine. Bought November 2003


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