Melting CR's. Timing? RPM? Multiple INJ?

Hamilton Cams said:
I think this directly points to the injector spray angles and the open piston bowl of the 04.5+ along with the pistons inability to reject heat and cool.
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I'm sure your opinion will be labeled as "theory" and not fact, but I would have to agree.
 
1911 guy said:
So with what you are saying about matching air to fuel triton. Is there a good rule of thumb to go by as in lbs per min on the turbo and ml per min on injectors? I know there are a ton of other factors that will ultimately affect air flow but with the multitude of set ups everyone runs, Dyno #'s and all the race teams conducting R&D for their setups Some one has bound to have seen a trend of air flow versus fuel flow #'s that produce reliable HP.

By the way where at in the NC mountains do you call home?
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If there's a formula to it, I don't know how to make the calculation. Guess all you can do is have a drive pressure gauge to make the determination. More fuel requires more air. Less air.... less time at WOT.

I recently tuliped a valve and you could tell there was a lot of heat hitting that valve. I would have thought, it being hot enough to do that to a inconel exhaust valve it for sure did damage to a piston or 2 also. Not the case. The ceramic coating on the pistons I believe made a nice difference in keeping them intact. The coating ( after 2yrs ) looked like it was just put on. The spray pattens in all the bowls looked just like they should.

Maybe I've been lucky... don't know. I just find it hard to believe that every CR out there is prone to a melt down. Just make sure there's a good air to fuel ratio and don't go crazy with electronics. If racing... well, problems are to be expected.
 
My head is coming off after x mas because of poss valve seat noise. I have a funny sound out of the exhaust intermittently and there is a slight rough idle when it is making the noise, almost sounds a feels like a miss. I wouls rather be safe than sorry.

Joe
 
JOESHTRDDSL said:
My head is coming off after x mas because of poss valve seat noise. I have a funny sound out of the exhaust intermittently and there is a slight rough idle when it is making the noise, almost sounds a feels like a miss. I wouls rather be safe than sorry.

Joe
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very well could be a valve.... those are the exact symptoms my truck had. It ran fine other than a weird noise and at idle, the whole truck would shake intermittently.
 
Erik@LCD said:
I will throw this into the mix, because it is kind of alarming to me (but good for business ;->


Last month we had a 125k '06 come in with a no start. Sounded bad, fuel through the intake, etc. Pulled the head. Found what amounted to combustion mud in 4 cylinders. Bad injectors. Rebuilt the motor.

100k 2006 drops seat and burns gasket. Cracked head. Running Smarty, 90hps, bigger charger. Ran some drag runs and a couple of sled pulls.

Low mile 2006 dropped a valve seat and toasted the gasket. 90hp injectors, and Smarty. Sent to dealer for warranty. Was a 6speed truck and had done some sled pulls, so figured high heat/rpm was the cause

Jason checked his contribution on his 2006 and found two low. Same scenario as above, but he had a cam, bigger turbo, stock injectors/cp3.

Two days ago, 2005 with 135k comes in with a funky noise. Eats a quart of oil every 400 miles. Excessive blowby. Pulled head, found #1 destroyed. Looks like a ring came apart. No obvious damage to the head and valves/seats on #1 look great.

Yesterday, no BS!!!, TWO trucks (2003 5speed SO truck with 135k and a 2007 with 155k, both stock) come in with poor running, smoke, funky intake/exhaust sound. The '07 is down 12% in cylinder two and he has already replaced injectors. The '03 runs so bad I told him to leave it. Both are getting the heads pulled over the next couple of days and I can't wait to see what we find.

Anyway, not sure how many of these are heat or injector related or how many are seat failures, but the fact that at least half are stock and fairly low miles for a Cummins makes me a bit nervous about the longevity of the common rails.
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In the name of research, we have been numbering the injectors as they come out on engine jobs. Send the injectors in to be tested and you will have a lot of answers. I think you will find bad injectors correlate with bad cylinders. That has been my experience.
 
The 04.5 piston can't sink the heat around the thin crown ring, that's were they all begin to fail. Only need one look at that cross section I posted to see that.
 
Just make sure there's a good air to fuel ratio and don't go crazy with electronics. If racing... well, problems are to be expected.
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Your logic is sound, but at what point does your ability to control this end? I agree with Zach that there seem to be as many non modified failures happening. I'm just basing this on hearsay over the last few years, I don't do repairs to make a first hand correllation.
If the fueling is incorrectly controled by the ecm for the conditions, you will never know until something doesn't feel or sound right, well past the point of no return.
 
What about adding water injection??, that should cool the crowns considerably, right?
 
It Works to a point, but in this particular discussion, it would only be masking a problem and not truely correcting it.
 
theory...egr effect in cams, and not ideal piston design, avaliablity of excessively sized injectors and lack of tuning knowledge by the end user...recipe for melt down?

side note; Marco pointed out to me there is NO three injection event in 04.5 and ups, it is cold engine strategy to SPLIT the main event to warm the cylinder...he proved it to by showing me his stock injection event data 03-04 compared to 04.5 and ups
 
ISBeINSIDE said:
theory...egr effect in cams, and not ideal piston design, avaliablity of excessively sized injectors and lack of tuning knowledge by the end user...recipe for melt down?

side note; Marco pointed out to me there is NO three injection event in 04.5 and ups, it is cold engine strategy to SPLIT the main event to warm the cylinder...he proved it to by showing me his stock injection event data 03-04 compared to 04.5 and ups
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I've seen that as well, on my scope.

scope1.jpg
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After the engine warms up, 2 events. However my truck's been in the shop and haven't had a chance to look under full load. I take it under load on the dyno, same story 2 events.....that throw's the third event theory out the window....:hehe:
 
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I would like to blame three events on melting pistons but if its not there...
 
Joesixpack said:
I've seen that as well, on my scope.

scope1.jpg
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After the engine warms up, 2 events. However my truck's been in the shop and haven't had a chance to look under full load. I take it under load on the dyno, same story 2 events.....that throw's the third event theory out the window....:hehe:
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Any idea at what coolant temp it switches?

Thanks,
Paul
 
It isn't that high seemed like it was only for a min and closer to the end of the warm up, if you rev'ed it a bit, it would go away, and back to idle it was there again. You can hear it when it does it, a little while into warm up listen and you can hear the engine change sound off idle.


I know I pluged the block heater in, while it was in the shop, and right of start up there was no third event.
 
so now we cant blame third injection event. So were back to spray angle and timming. So i understand correctly, larger nozzles theoreticaly advance timming, ( I cant really see how this is in a CR type injection system since injection is actuated by means of an electronic solenoid) and increased RP increases Static Timing? Some one please explain what Static timing is.
 
Also did i read correctly that there is a stand alone ECU that is programable and will deliver fuel in one solid slug?
 
the duration of the injection event can cause issues as well...that is really why i think the smarty/tst stack is very effective due to increased duration past what the smarty alone can provide
 
yes the standalone is capable of this event, but pilot really does work well to quiet the injection events
 
ISBeINSIDE said:
the duration of the injection event can cause issues as well...that is really why i think the smarty/tst stack is very effective due to increased duration past what the smarty alone can provide
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So do you run a smarty TST stack? I started a thread recently about how exactly the TST operated and not one person posted. Im wanting to know what exactly in the injection event is being manipulated when adjusting Power versus Torque on the remote. One is adjusting pulse width duration and the other is tweaking the timing? I really wish TST had a vendor section so questions like this could be answered by the man himself.
 
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