Duramax and Cummins

J

jjv101

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Feb 9, 2010
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Before anyone jumps the gun this is NOT ment to be a vs thread!

Basically I am looking into getting a newer truck and would like to stay with diesel (although havent totally ruled out a gasser) However I dont know too much about duramax's and I already own a 2001 Cummins.

My question is in the 2004-2007 Duramax was are the main issues involved? How much HP can the stock transmissions hold (~100 correct?) and how much power can the stock internals take before reliability goes bye bye?

Now same with the Cummins...for say 2003-2007 5.9L. How much power can the stock internals of the engine handle? (we all know the auto trans are weak under added power) What other problems are there with these trucks?

Basically my goal for a truck is a reliable and fun daily driver that I could take to the track once in a while or just have fun with on the highway! HP goal I would say around 500ish and would either get a built auto or 6spd(cummins only...not sure which though)

Thanks in advance for the help!
 
You won't need to worry about the internals of a Cummins at that level. They've been known to make 1k+ on a stock rotating assembly.
 
500 rwhp will not be a problem for Duramax internals.

I am unsure what you're asking about the "main issues".
 
I think 04's Dmax still had LB7's... If it is then it is injectors.

Whatever engine family came after, had overheating problems... I don't know much about those either.
 
I think on both your going to want to make sure the fuel system (injectors, cp3, lift pump) are all healthy because as we all know that injector failure especially on a common rail can be catastrophic.

Valve seats on the earlier Common Rail Cummins have been problematic, I have now owned 2 2003's that have had valve seat issues. I believe you do not run into this issue in the later models (2005 and newer) as much.

I can say that the Duramax responds very well to tuning whether it be your average PPE downloader or customer tuning with EFI live. If you are just planning on tuning the truck and not getting into heavy mods I would say your going to get more power out of a dmax with EFI live than you will with a cummins with just tuning.


Once you build the 48re it is ready for a beating and will hold up just fine.


Get a 06 or newer cummins and get EFI live tuned or Smarty SSR and rock out.
 
I thought you meant main bearing issues, I read it wrong.

550 rwhp seems to be the general consensus of the reliability threshold of LB7/LLY rods. The LBZ/LMM rods will handle 100-150 rwhp more.
The Daewoo pistons have been a concern in the LBZ/LMM. Daewoo had poor quality control...some crack with a small tune, others will take whatever you can throw at it.

Quality tuning (and a level head) can/will increase these estimates...these seem to be the "low end" (i.e. before efi) of the spectrum.
 
Thanks you everyone for the info thus far!

rollincoalCTD said:
I think on both your going to want to make sure the fuel system (injectors, cp3, lift pump) are all healthy because as we all know that injector failure especially on a common rail can be catastrophic.

Valve seats on the earlier Common Rail Cummins have been problematic, I have now owned 2 2003's that have had valve seat issues. I believe you do not run into this issue in the later models (2005 and newer) as much.

I can say that the Duramax responds very well to tuning whether it be your average PPE downloader or customer tuning with EFI live. If you are just planning on tuning the truck and not getting into heavy mods I would say your going to get more power out of a dmax with EFI live than you will with a cummins with just tuning.


Once you build the 48re it is ready for a beating and will hold up just fine.


Get a 06 or newer cummins and get EFI live tuned or Smarty SSR and rock out.
Click to expand...

I would like to get a 06-07 duramax or a 04.5 or newer cummins, As far as mods I wouldnt be going too crazy. Built trans (if auto) Tuning, fuel supply, set of injectors (nothing to crazy) and maybe a turbo upgrade if needed due to injectors and tuning.

as far as other problems, has dodge finally fixed the rusting problems on these 3rd gen trucks as compared to the older ones? And if I go cummins im not sure about the auto trans or 6spd. My dads been having issues with his lightly built 47re and I really dont want to deal with the electrical and solenoid problems that could occur
WhitetailAddict said:
I thought you meant main bearing issues, I read it wrong.

550 rwhp seems to be the general consensus of the reliability threshold of LB7/LLY rods. The LBZ/LMM rods will handle 100-150 rwhp more.
The Daewoo pistons have been a concern in the LBZ/LMM. Daewoo had poor quality control...some crack with a small tune, others will take whatever you can throw at it.

Quality tuning (and a level head) can/will increase these estimates...these seem to be the "low end" (i.e. before efi) of the spectrum.
Click to expand...

I would defintely like to get a LBZ motor if possible, I know the allison will need to be built to handle more power. As long as theres no main issues with the motors and rest of the truck that will leave me stranded i am seriously considering a dmax. But it sounds like 500hp is nothing for the cummins and 500 is safe for the dmax too so thats good to hear!
 
oldestof11 said:
I think 04's Dmax still had LB7's... If it is then it is injectors.

Whatever engine family came after, had overheating problems... I don't know much about those either.
Click to expand...

late 04's have the lly look at the vin the 8 digit. if it is a 1 it is a lb7 if it is a 2 it's a LLY
 
RSEfab said:
late 04's have the lly look at the vin the 8 digit. if it is a 1 it is a lb7 if it is a 2 it's a LLY
Click to expand...

LLY overheating is cured by putting the $99 LBZ turbo mouthpiece on it.
The LLY mouthpiece has a very sharp internal bend that causes significant turbulence and charge air heating.

Sent from my Galaxy Nexus using Tapatalk
 
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