Competition Duramax engine issues

[zstroken]

Check this thread out. It is pretty amazing I didn't make it through all 33 pages, but what I got out of it is that seveal of the street boys are running built engines. Just kind of surprised me, as most of the dodge camp just oring or firering and stud the engine and go racing.



http://www.dieselplace.com/forum/showthread.php?t=114322

 

[mwgasman]

Duramaxes are very good at bending rods and windowing the block. I have seen and heard it. Nothing like dumping all of the fluids out of the motor in the middle of an intersection.



They are still blowing motors (cracked pistons etc) even with a set of $8000 (yes, EIGHT THOUSAND DOLLARS) rods and LBZ pistons.



The blown motors is the reason I sold my Duramax and bought the Ram/Cummins.

 

[jwilliams3]

The first set of pictures on page 13 are typical melt failures (seen it more than a few times). That kind of piston failure happens in seconds. No aluminum piston will hold up to the kind of temps that make that type failure happen.



The 2nd set pictures of split cracks looks like a fast change temperature condition that exposes the inherent weaknesses in the Duramax's piston integrity and causes the piston to crack (my opinion).



Breaks my heart!! :-laf

 

[WUnderwood]

slightly off topic, but how many injection events do the Duramax's have? I know the 04. 5+ Cummins have 3

 

[mwgasman]

LB7 and '05 LLY Duramaxes have 2 injection events. The newer engines ('06 LLY and '06+ LBZ) have up to 5 injection events.



Let me tell you, I miss EFILive terribly. That program is the BEST tuning tool. Period. I was able to write tunes that were very drivable and able to produce the same HP/TQ as my stacks within 2 weeks starting from scratch.



If we can get full pulse width, timing, rail pressure, and pilot injection control the sky is the limit. As I am sure you are aware, no "box" or preprogrammed module will provide the flexibility and power to be had by customized tunes.



A great disservice was done to EFILive and programs like it by the recent thread here on TDR. EFI is no "box" that is plugged in to the "ground wire" at the OBD connector. Your laptop is connected to the OBD connector. Tunes are easily flashed in to the ECM, and datalogging can be done for ANY parameter the ECM measures.



I can only dream of the day that we have this control. An SCT type system wil be next to useless for highly modified trucks. We need real control. Until then the Dmaxes will continue to gain and surpass us. (Unless of course they keep breaking motors)

 

[jwilliams3]

A great disservice was done to EFILive and programs like it by the recent thread here on TDR. EFI is no "box" that is plugged in to the "ground wire" at the OBD connector. Your laptop is connected to the OBD connector. Tunes are easily flashed in to the ECM, and datalogging can be done for ANY parameter the ECM measures

My thoughts exactly! Funny how SOME of the people asking about it have no idea what it even is or what it does.

 

[zstroken]

The 2nd set pictures of split cracks looks like a fast change temperature condition that exposes the inherent weaknesses in the Duramax's piston integrity and causes the piston to crack (my opinion).



Breaks my heart!! :-laf

I disagree, that looks like more of a fatigue issue, they are breaking right on the wrist pin line. Looks just like a weak piston. They have said they have seen more of this since they have corrected the weak con rods. Also the LB7 has stronger rods and stiffer block, so the next weakest point would be. Could be from excessive timing, heck might even be from harmonics that become present at certain RPM. The melting I agree with.



I do a lot of reading over there in the competition forum. What I though is ironic is how much hou hear about what a dual purpose(racing sled pulling) engine the DMAX is and they are talking about the number of failures of engines. Probably 4 of them run the DHRA street class. Just makes me wonder how many more of the DMAX guys have non stock internals.

 

[fest3er]

I disagree, that looks like more of a fatigue issue, they are breaking right on the wrist pin line. Looks just like a weak piston. They have said they have seen more of this since they have corrected the weak con rods. Also the LB7 has stronger rods and stiffer block, so the next weakest point would be. Could be from excessive timing, heck might even be from harmonics that become present at certain RPM. ...

As I posted over there, the most likely cause of the broken pistons is excessive peak cylinder pressure. Remember, the Duramax crank has a shorter moment arm; thus it needs greater cylinder pressure to generate the same torque as does the Cummins. And if the fuel is not controlled well, I can see peak pressures being high enough to snap the piston.



The Duramax is, what, 6 years old. That they've come so far, performance-wise, in such a short time is impressive. So why isn't the Cummins CR keeping up?

 

[RZeedyk]

$8000 ? I will sell you 2 sets for that price.

 

[lmills]

the Duramax is, what, 6 years old. That they've come so far, performance-wise, in such a short time is impressive. So why isn't the Cummins CR keeping up?

So what's your point? I think the common rail has done well since it has just entered it's 4th year. Your comparing it to an engine that has been around for 2 more years. Not to mention 2 years ago you would have never heard of a 675-700 HP duramax on #2 only. There have already been a few common rails so far in our 4th year. And regardless of the price of the replacement rods. The bottom line is they still need them to live

 

[jwilliams3]

The Duramax is, what, 6 years old. That they've come so far, performance-wise, in such a short time is impressive. So why isn't the Cummins CR keeping up?

Keeping up? When did you start pulling your arm chair or racing your lazy boy? :-laf

 

[MTomac]

If you're not getting stupid with tuning, drugs, extremely high egts, ect. the stock Duramax pistons and stock Duramax rods are just fine in the 600-700 rwhp range.

 

[mwgasman]

If you're not getting stupid with tuning, drugs, extremely high egts, ect. the stock Duramax pistons and stock Duramax rods are just fine in the 600-700 rwhp range.

True, but the Cummins lower end seems fine with stupid drugs and tuning. It usually blows the head gasket before it breaks the bottom end.



Good to see you over here Mike.

 

[zstroken]

If you're not getting stupid with tuning, drugs, extremely high egts, ect. the stock Duramax pistons and stock Duramax rods are just fine in the 600-700 rwhp range.

I agree, as you have proven that a DMAX can win the east coast challenge. What I thought was ironic is that a few of the guys over there talk how superior the DMAX is tot he cummins. The Dmax is a good engine. What is the most ironic is the guy that was trash talking the most recently put a hole in the side of his engine. Is this some of the reason you haven't put in the LBZ engine that you have yet? Also this was really the first I had heard of the issue. As the conversation started out it seems like there were only 2 but as it went along, it seemed more and more have done the same thing and noone new about it.

 

[nwpadmax]

They are still blowing motors (cracked pistons etc) even with a set of $8000 (yes, EIGHT THOUSAND DOLLARS) rods and LBZ pistons.

MW, are you smoking dope? $2500 billet rods + $1200 LBZ pistons.



That's less than $4000 (yes, FOUR THOUSAND DOLLARS) :-laf

 

[zstroken]

Yea but still 4x the price of a fire rings, and studs. Not counting the labor. I figured I could get some dieselplace guys over here with this post. What I find the most amazing how lots were complaining about putting money in the dodge engine, and then all of the sudden I found out that there are just as many guys putting more money in the DMX engine in a street class.

 

[nwpadmax]

Zstroken-



You seem to be a decent guy and as far as I'm concerned you're welcome on the DP (from one member to another).



However, from my perspective, you're exaggerating things a bit. You say above "lots were complaining" and you mentioned before about the trash-talkers.



There are a few of those guys, but geez, ya don't have to listen to 'em, and I don't think they represent the majority of the DP members. Every site has its talking heads, this one included.



Are ya tryin' to stir the pot? How about we all just get along! :-laf



Anywho, yes, there are some guys spending what seems like stoopid money on Dmax parts to run in street classes. The parts costs are stoopid because there are only 2 or 3 vendors and the number of parts sold is tiny. We're all steenkin' beta testers really.



The Cummins is stronger in the stock format, I think that's been decided a while ago. Correct me if I'm wrong, though, the main guys being complained about were Painter and Miller, and I don't believe you're actually suggesting that all they had done was fire rings and studs



I don't think anyone was complaining about yourself, Coppess, Amos, and guys like that with sane trucks for the class.

 

[Kyle03D]

dodges suck

 

[Signal73]

dodges suck

:-laf

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[nwpadmax]

dodges suck

I take 500 words, Kyle takes two :-laf