jfdid

Will the pistons from the 2003 engine fit on the rods of a 2006 5.9?
Will it change the displacement?
Is there any other problems you can think of?

Anyone have the cost of the pistons/rings?

no_6_oh_no

They will fit but you can't use them. Piston bowls are different for the different spray angles of the injector tips. No worky.

Spooler

It has been done before. CompD has a thread about it. From what I remember you have to change the injector nozzles to make it work properly.

no_6_oh_no

Exactly, and loose power in the process. Even though the pressure will make up for some of it the 03-04 tips have less holes and smaller size so less overall fueling. To compensate it would take larger injectors as the stockers start to run out of flow by 450-500 hp. Physically nothing to prevent it but there are other things that need to be addressed.

Not sure on the compression but just guessing maybe 1/2 a point due to the bowl configuration. Other impacts due to the timing and funky valve profile is unknown. Change out the cam and that is moot.

JJPage

The 03/04 injector tips have 8 holes vs 5 holes for the 04.5+ years. The 03/04 tips also have a wider spray angle than the newer trucks, which prevents the 03/04 trucks from utilizing more advance timing, without spraying outside the piston bowl.

I would not do it, the third injection event and other factors on the 06, just do not make for a good mix with the earlier pistons.

Spooler

The thing is it is being done successfuly. Couple of folks on CompD are running it.

JJPage

It's hard to figure what the advantage of running 03/04 pistons in a 04.5+ truck could be.

I'm not doubting you, or that someones got it working efficiently, folks are resourceful.

no_6_oh_no

Very little info available on how good it is, what was done to make it work right, or the long term results.

JUST replacing the pistons will NOT work without catastrophic results. Thats a given. No info on the benefits of doing this that I have seen. That thread you referenced has more than few flags about what happens if you don't do it right also. Gotta look at the big picture and not just a piece of it unless rebuilding the engine is a hobby one likes to do frequently.

XLR8R

The 3rd injection event isn't really an issue - and the ECM can be swapped if you believe it matters (works fine either way). Camshafts aren't different.

The 555 motor's re-entrant injector tip & piston bowl design are proven to make more power than the 610 series... and Cummins switched back to re-entrant spray geometry on the 6.7L for good reason.

Not much reason to interchange parts for the average rebuild or daily driver, though.

no_6_oh_no

Re-entrant bowl design was developed in response to emissions and is still used to achieve that end. Past a certain point it is actually detrimental as the lip ends up being the start of hot spots and cracking. The Duramax uses this design and they have way more problems with pistons than the Cummins.

A re-entrant design relies a lot on valve placement and timing, injector spray pattern and number of holes to function efficiently. Change too many of those parameters and it ends being a detriment rather than help. In a large bore engine its an attempt to promote better mixing of the air\fuel. Theoretically that will make more power but the constraints are a lot tighter on how much and the conditions that promote the power.

XLR8R

Re-entrant doesn't just theoretically make more power - it has done so empirically... 610 motors haven't run the same numbers.

N.Johnson

I have got to ask for you to please clarify the difference between theoretically and empirically on the 555 versus the 610. Really would like a schooling if you got the time....

XLR8R

You mean geometry differences?

'03-'04 piston dome 113*
fuel injector spray 143*

'04.5-'07 piston dome 140*
fuel injector spray 124*

or fueling differences?

i.e.
555's make best power with F6.X sticks

610's make best power with F5.X sticks.

or the ECM?

3rd injection event has been shown to have an insignificant effect on power production.

or ???


There are a few differences between them that favor the 610 motors - such as the ability to run more timing due to the spray/dome angles - but they are apparently outweighed by the re-entrant design's superior efficiency.

Re-entrant vs. non re-entrant theory is another discussion.

N.Johnson

Thanks for the numbers difference on the piston geometry, never knew that. I have held the two types in my hand and noticed the 03/04 are a deeper cut into the bowl, I think. I'm going out on a limb here but.... is this why the 555 doesn.t like as much timing as the 600/610 piston. Why, in your opinion, did cummins/mopar change the injector hole geometry from 8 holes/555 to 5 holes/600-610. Yes they improved the emissions out the pipe with a cat, but why did it increase the torque and horsepower? Thanks for the reply dude, great info