Exhaust gas pressure limits?

[Rawze]

(06-21-2022 )Badger Wrote:  ...
the reason i rebuilt it last time was because i had a fire ring burn out of hole 2, broken ring on hole 5 or 6, and the injector cups leaking in the head, and the injectors had 1.3 million miles on them so i just did them while i was in there.

-- note that this time around it was small hp 8520cpl , and i swapped pistons and turbo to 8518 and wedged the cams to 4/6. so im not getting greedy with HP, i just want a reliable 565 hp, should be easey peasey since they came factory with that much and more. ( even before cpl and tune changes this general " egt / boost issue" has always been there, not from the cpl change alone)
...

If a fire ring got damaged, then a liner was dancing in the block. I hope you counter-bored it and raised the liners to 0.015".. otherwise you have not extended the life of that engine at all by replacing those things. It will not make it a few years, and you will be right back taking it apart yet again.. and replacing that head all over again due to another dropped liner.

Your post also states that you may have swapped some of the components on the internals too?.

Here are the actual differences...

CPL8520 engine uses part#'s ...
oil cooler: LC1737-04 (single element).
crankShaft: 4925761
turbo: 4036666 (fuel savings turbo)
piston: 4923747

CPL8518 engine uses part#'s ...
oil cooler: LC1736-05 (dual element).
crankShaft: 3681910 (increased oil flow)
turbo: 4043214 (higher heat turbo)
piston: 4923743 (lower compression)

All of the other components with regards to performance are the same between those 2 builds. Same injectors, same head, same cams, same valves, etc.

By using the lower compression pistons of the CPL8518 and the bigger turbo, the engine is going to be measurably less fuel efficient, mostly due to that turbo. I have seen people loose 1+ mpg by switching to that turbo model to only later regret it unless they had a specific need for it. Even with higher HP, the engine does not need that bigger, less efficient turbo on it, unless you are heavy-hauling.

With the lower compression pistons, different injection timing and other settings need to happen to get it programmed correctly for that type of custom build. The higher rpm injection timing curve needs to be corrected. Also if you used the 4/6 wedge, you will need a program that matches this different mechanical setup too.

I.E.> you have kind of created a bit of a mess with it, and likely for no good reason at all, especially if all you wanted to do was bump it up to 560~ish hp. It already had the bigger tier(1) injectors in it, valve/injector cams, ect. and that is most of the cause that would have built extra heat and stress at higher HP levels, .. so that was never the issue. Seems to me that Someone somewhere has lead you down a rabbit hole on that one.