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

[ISBeINSIDE]

yes i run at smarty/tst stack...smarty tnt-r/ with tst set low on only power levels, marco and i had some issues get the smarty to increase duration past a certain point on just the smarty, so tested with tst on and picked up 30-40hp on same smarty settings...as for actual tst manipulation i can only guess on what settings do what when, seem to be pretty accurate guess though

 

[Cantankerous1]

I've seen that as well, on my scope.

[/IMG]

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:

What rpm is that run at? You will likely not see the 3rd event or extension to the main event until much higher rpm's and load. Get a run where you load it over 50% and over 2500 and you will see a pulse that is more of an extension fo the main event thna clear 3rd event.

I would like to blame three events on melting pistons but if its not there...

Its there in some form as I have seen the trace on a scope. That event is load and rpm based. Its pretty easy to see it on the stock turbo with a drive pressure gauge when and where it activates.


Like I said previously, that event is purely under the ECM control and none of the prgrammers seems to be able to control it. It takes whatever percentage the OEM protocols say and applies it. Large injectors, extended duration and pressure will put a LOT of fuel late in the combustion sequence and start the burn cone outside the bowl. With the lighter piston and non re-entrant bowl design the combustion area is getting too wide to be contained where it should be.

 

[ISBeINSIDE]

Marco seem to express to me was...he didnt see a need to control/manipulate the split second event

 

[Joesixpack]

What rpm is that run at? You will likely not see the 3rd event or extension to the main event until much higher rpm's and load. Get a run where you load it over 50% and over 2500 and you will see a pulse that is more of an extension fo the main event thna clear 3rd event.



Its there in some form as I have seen the trace on a scope. That event is load and rpm based. Its pretty easy to see it on the stock turbo with a drive pressure gauge when and where it activates.


Like I said previously, that event is purely under the ECM control and none of the prgrammers seems to be able to control it. It takes whatever percentage the OEM protocols say and applies it. Large injectors, extended duration and pressure will put a LOT of fuel late in the combustion sequence and start the burn cone outside the bowl. With the lighter piston and non re-entrant bowl design the combustion area is getting too wide to be contained where it should be.

What I showed is only at idle, and like I said, have only scoped it under no load. As soon as its back together I'm going to post some data logs of the injection events under full load.

Should be able to see the whole picture.

 

[ISBeINSIDE]

the scope picture i have seen showed up all conditions as far as i know overlayed the 03-04 inj events over the 04.5 and up's scope they were identical to the tee...

 

[Cantankerous1]

Marco seem to express to me was...he didnt see a need to control/manipulate the split second event

Marco doesn't because he is not into unknown regions with other fueling mods stacked with the Smarty either. Nor is he repeatedly replicating the conditions that a lot of people hit in their unsated quest for power.

the scope picture i have seen showed up all conditions as far as i know overlayed the 03-04 inj events over the 04.5 and up's scope they were identical to the tee...

Without enough load it may not even show on a scope. Unless there are load percentages and rpm's with the graph its hard to tell what was happening.

Cummins billed it as a third event, Marco calls it an extension to the main event. Either way something is kicking hard in the high load high rpm range to drive drive pressures the way it does. Its possible to run the engine all the way to redline and never see a spike in DP also so there some other parameters than just rpm controlling it.

Its been 4 years but IIRC the one I saw was a fairly smooth extension of the main event that smoothed the duration and cycle in quite well with the main pulse. You could tell it was extending it as a percentage of rise and run but not that it was a distinct entity.

Even that portrayal is suspect cuz I never got a full description of the conditions around it. It would very interesting to see multiple runs under multiple conditions and the effect it has on the duration and delivery. I am just theorizing but if oyu stack enough fueling on a program that cannot control this extension you are naturally going to get a lot of fuel late in the event that is going to start getting outside the optimum burn zone.

It really hasn't been an issue until we now have the capability to push the fuel to the 04.5+ engines like the 03-04 ones and they start to fail. I am pretty sure its not going to be one single thing that contributes but a combination of several.

 

[Smokem]

Large injectors, extended duration and pressure will put a LOT of fuel late in the combustion sequence and start the burn cone outside the bowl.

With a 124° pattern in a 76mm bowl? When the 143° pattern in a 56mm bowl has a fraction of the failures? The heat concentration is too narrow, not too wide.

 

[2007 5.9]

Marco doesn't because he is not into unknown regions with other fueling mods stacked with the Smarty either. Nor is he repeatedly replicating the conditions that a lot of people hit in their unsated quest for power.
For now...that is soon to change.


Without enough load it may not even show on a scope. Unless there are load percentages and rpm's with the graph its hard to tell what was happening.

Load has nothing to do with it.

Cummins billed it as a third event, Marco calls it an extension to the main event. Either way something is kicking hard in the high load high rpm range to drive drive pressures the way it does. Its possible to run the engine all the way to redline and never see a spike in DP also so there some other parameters than just rpm controlling it.

It isint a 3rd event, what you are seeing is the point when the stock turbo becomes in-efficient. Put a aftermarket turbo on and you wont see DP spike at the same boost #.

 

[Soup Nazi]

Crown temperature is higher in a longer window of time on the 04.5.

The bottom line becomes that the fueling is too high for aluminum to hold up long on many of these set ups. As always more airflow helps. As does water.

The ring package has been found on the tight side in most the CR engines from the factory too.

Contrary to what some are posting, the injectors are a huge issue. Many of them are not firing when asked. For varying reasons. Some are sloppy internally with leaks and some have sticking needles/pintles and control rods. Or a combo of it all. Higher rail pressures past factory values show us wear patterns on the pintles from the needle rocking and flexing too.

 

[ISBeINSIDE]

IMHO...the system as a whole would be the concern, egr in cams, cylinder pressures due to boxes/downloaders, turbo and injector combos, it is all THE issue, in the end good tuning and the humility to ask the questions and get a good answer...even if it is outside the general belief system, is going to help us understand "what" it is we are dealing with.

 

[outlaw99]

when you say tuning how without a true datalogging system can we tune a cr truck to where we would feel confident it wont melt?

 

[Joesixpack]

With a 124° pattern in a 76mm bowl? When the 143° pattern in a 56mm bowl has a fraction of the failures? The heat concentration is too narrow, not too wide.

The piston almost always fail in the crown area, lots starting from the outer most diameter of the piston. (Black ellipse)

There is not enough meat to sink this heat from the crown into the body of the piston, or oil cooling jacket. (Red ellipse)

In Diesel RK when I model'd this piston the yellow line indicates the flame front and what seemed like an extended release period in the crown area.

When you model the 03-04 piston and you get into a excess fuel condition this is wraped around the bowl and back toward the injector.

The 03-04 is not seeing the same heat release in this area, and further more HAS more meat in the crown area to deal with it.



IMO the 5 hole injectors are getting the fuel to far out. And hogging them out only aggravate's the issue.

I'd bet a bag of marbles a 8 hole with less spray penetration is the ticket.


Never did model it.....After the steel pistons, I have little concern of this issue now.....

[/IMG]

 

[Smokem]

IMO the 5 hole injectors are getting the fuel to far out. And hogging them out only aggravate's the issue.

The entire piston surface area is being subjected to excessive heat, not just the crown. If your idea was the case, why would a 153° pattern nozzle with 40-45° static timing not torch the crown, especially with 2000°+ cylinder temperatures? It is as simple as looking at Don's avatar.

 

[Joesixpack]

Good grief, never even noticed Don's avatar....its showing exactly what I'm describing and the non re-entrant bowl.

 

[Smokem]

Contrary to what some are posting, the injectors are a huge issue. Many of them are not firing when asked. For varying reasons.

Not contrary, Zach posted that.

Some are sloppy internally with leaks and some have sticking needles/pintles and control rods. Higher rail pressures past factory values show us wear patterns on the pintles from the needle rocking and flexing too.

Not contrary, my post about the double guided needle, and the fact that the 6.7L has gone to a micro-blind Sac design, which were removed.

 

[Cantankerous1]

It isint a 3rd event, what you are seeing is the point when the stock turbo becomes in-efficient. Put a aftermarket turbo on and you wont see DP spike at the same boost #.

Of course it won't spike as high or at the same boost numbers, its not boost specific its load specific and opening the flow is going to change when and how it shows. With a well tuned turbo you get rid of the spikes and just smooth the whole DP rise, the intent of the DP is provide a larger EGR charge to offset the emissions generation at high load high rpm. Remove the components that facilitate it and the evidence goes with it.

With a minimal engine load the spikes do not happen as the rpm goes up, the increase in DP is much more linear. Only under high load does the spike appear.

 

[poindexter]

So I read and read and just wonder how much longer I have till my 05 with 47,000 miles craps out ,you can see in my sig mostly stock,want to have a500 to600 hp truck,but not to sure now.even stock trucks seem to have issues.

 

[Chris Mallett]

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.

The piston almost always fail in the crown area, lots starting from the outer most diameter of the piston. (Black ellipse)

There is not enough meat to sink this heat from the crown into the body of the piston, or oil cooling jacket. (Red ellipse)

In Diesel RK when I model'd this piston the yellow line indicates the flame front and what seemed like an extended release period in the crown area.

When you model the 03-04 piston and you get into a excess fuel condition this is wraped around the bowl and back toward the injector.

The 03-04 is not seeing the same heat release in this area, and further more HAS more meat in the crown area to deal with it.



IMO the 5 hole injectors are getting the fuel to far out. And hogging them out only aggravate's the issue.

I'd bet a bag of marbles a 8 hole with less spray penetration is the ticket.


Never did model it.....After the steel pistons, I have little concern of this issue now.....

[/IMG]

That is the only problem my 05 was showing also. A couple dumba$$es tried to look over it and did not adjust valves correctly, caused a problem and bent two pushrods. This is when I bought my truck and it had 252K on it. Hotshot rig its whole life.

So what you are saying Joe, a non re-entrant bowl and 8 hole sticks (I hvae seen 10 hole sticks somewhere) would be the ticket?

BTW I am kicking myself in the ass for not listening to you about the second ring last year. The crappy advice from local Cummins mech. did not work out for me. I tow now and get excessive blowby. DD is not an issue, but extended boost builds crank pressure when hooked to a load. This is why I want to get my build right for next time it comes out. :bang

 

[ISBeINSIDE]

who has a cross section of a 03-04 piston? can they post it please?