CR melted piston discussion, why, why not, and for the love of god how not to..

joelc79 said:
besides bdp who has burn't up a 03/04 motor?
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i have built 4 of them due to burn pistons. 2 of them bone stock 2 modded but not to any great extent. injectors were the problem in every one of them. spraying on top instead of the bowls.. fixed the engines had the injectors fixed or replced no problems since


I wonder what the temp of the fuel is at the time of injection. the temp has to increase quite a bit for every 1000psi the preasure goes up

ted
 
i have one for you guys. i have an 06 at the shop that blew a turbo. local fixerupper guy put a turbo on it. he started the truck without cleaning the intercooler and the truck ran off :bang when he started it. after it shut down it didnt sound good. ended up at my shop after that. # 6 is a melted mess top is burn like the others where the spray patern was also burnt down past the rings. only #6 is hurt.

ted
 
Just wanna throw a quick thought out here. The duramax's have the same injection system as the cummins, but they don't seem to be having the melting piston problems we see with the cummins. They would surely have had to go through the same teething process as the cummins, with all the talk about "lean" burning and melting up pistons. They run the same pressures, HIGHER rpm than a dodge cr, flow more air therefore making them a better candidate for "lean" melt downs. If the melt downs were due to running lean, Duramax's surely would be a perfect candidate. Do they have three injection events? (honest questions here) They can run more timing. What kind of piston design do they have? Anything about a combustion process we theorize here needs to be applicable to any cr application. From what i'm seeing very few of the theorys flying around stand up against the Duramax cr application. I'm leaning more towards the injector and piston designs.
 
d max injectors seem to be way better than ours when it comes to living at high preasure
 
Not only that the HIGH horse guys can TUNE (efi live), we get to pick a number and hope for the best.

Just do a search "melted pistons" on the group of forums........you guessed it cummins 04.5 and up common rails is way out of hand.
 
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Joesixpack said:
Not only that the HIGH horse guys can TUNE (efi live), we get to pick a number and hope for the best.

Just do a search "melted pistons" on the group of forums........you guessed it cummins 04.5 and up common rails is way out of hand.
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i did guess it, hence the purpose of my post. Great they can handle higher pressure, that goes to prove my point of design of injector, and or piston.
 
yes it does, far different than melting however.

By the way to be clear, i'm not here to tote how much better a duramax is than a cummins. I am, like I said throwing out some idea's.
 
Devan Manis said:
Just wanna throw a quick thought out here. The duramax's have the same injection system as the cummins, but they don't seem to be having the melting piston problems we see with the cummins. They would surely have had to go through the same teething process as the cummins, with all the talk about "lean" burning and melting up pistons. They run the same pressures, HIGHER rpm than a dodge cr, flow more air therefore making them a better candidate for "lean" melt downs. If the melt downs were due to running lean, Duramax's surely would be a perfect candidate. Do they have three injection events? (honest questions here) They can run more timing. What kind of piston design do they have? Anything about a combustion process we theorize here needs to be applicable to any cr application. From what i'm seeing very few of the theorys flying around stand up against the Duramax cr application. I'm leaning more towards the injector and piston designs.
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My buddy's 07 lbz melted and broke pieces off 2 pistons and scored to walls, bad enough to need to be re sleeved. Plus their known for bending rods.

He had 2 bad injectors. I guessed excess RP from puck.


Another buddy with 06 lbz has cracked piston across top, running efi live. and a turbo.
 
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aer212 said:
Stock cams on the melted ones or not? Someone answer!
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most i have seen have had stock cams, but all have had injector issues. i did a couple with cams in them they were not melted to the extent of some pictured on here, but still melted
 
Aren't the dmaxs having some pistion problems too. I thought they were injecting that hard that they were putting indents in the pistons
 
EFI live can turn off the pre-injections, which according to a really good tuner I know is one of the key things he does.
 
Are the 6.7 Injectors and the 5.9 Injectors(03-04) the same? If I recall the 6.7's have a few more kpa on the injection pressure. That would save some injectors from the RP issues if the 6.7 injectors are capable of withsanding higher pressures.
 
One thing on timing is you are limited to how much timing you can run on a 12V. Too much and you can't spool. On a CR it's a differant story with variable timing. So at high rpm the CR is operating at more advanced timing than a 12V. "More in cylinder heat"
Billy
 
How many degrees of timing advance are we talking about with these programmers? Are those numbers known or classified?


Is that something that can be read with a scan tool or would you need an oscilloscope on a dyno?
 
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