Let's talk about this ring land thing...

Maybe we can get a couple of engine builders in this thread to explain their reasoning.

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I don't think so on the 6.1. I'm looking at a stock piston right now and both the groove and ring appear square on the edges.

 

Ok. I'll buy that. Can you see in the gap to the back side? somehow I thought they might be beveled.

Oh, heh, the picture just showed up! wow, those are some really large gaps. you won't break any top lands with those.:shok: :grin:

 

Yeah, they're quite a bit smaller when compressed to fit in the cylinder. The service manual specs the top ring gap at 0.30-0.40 on a stock 6.1.

 

Does anyone have a picture of a broken ring land?
I see gapping of biththe 1st and 2nd ring.
If you gap the second ring a little more than the first you could release excess pressure between rings toward the sump.

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Here you go. And every one that I have seen breaks that the top like this.

 

Here's a better indicator guys.

 

I know that (it was a funny). So what ever happened to rings that you have to put in right side up?

 

Interesting burn pattern from looking at the combustion deposits......

Do I notice that the break is where the gap is?

Would the gap migrate ti the top due to weight or...? (This question not necesssarily related to first question.)

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I wont to add what I have seen in the last 30 or so engine builds. Each stock motor that came in that had forced induction or NOS had several broken pistons. They were replaced with forged pistons and they still failed. The builder I use went to a taller top ring land and the problem went away. The problem cam back when the motors were stroked and a valve release was added to the piston. This area now became the weak spot and they started breaking again. New piston design is in the works and will be out soon.

 

A piston being forged but still having the shalow top ring land, as we now know, only helps a little and that is not enough.

I think Chrysler knew someting.... that is probably why they hard anodized the piston top.

Anybody have any ideas as to why the land only breaks at the top of the cylinder?
Direction of force on the piston?
Proxiimity to intake valve, why would this be related?

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I think because its the thrust side and genenrates the most friction -> heat. I haven't seen the entire HEMI water jacket yet, but I'm willing to bet that there is significantly less water volume up there for cooling too.

 

Good read.opcorn:

 

so this is coming from neonland but, most ring land breakage i've seen on the 2.4 occurs from predetonation, now i dont know if its from the direct force of the predet on the piston top, or if the ring is fluctuating in its land as a result of the predet, either way it pretty much breaks a motor without fail