Why Apex Seals Fail

[TitaniumTT]

It seems to me that the stain is in line perfectly with the fin. It appears to me that the fin has kept that area from growing. Effectively retracting it as the rest of the housing grows. Looking at the 16x and the renni, they seem to aleviate some of this material. I'm wondering if this is in an attempt to not contain it, but to let it grow a the same rate. Thoughts?

[vex]

Originally Posted by Barry Bordes

If you look closely at this photo you will see the Racing Beat type grooves in the this first iteration cooling mod.

It didn’t seem to help much to alleviate the growth problem as I had hoped.

The next set of mods included severed fins and larger balanced passages.

Barry, as NoDOHC mentioned I do not think balancing the flow in the passages will help alleviate the problem. The issue I believe may be compounded by too high a temperature difference in the cooling surfaces (IE across the passages). Physically speaking you have a large temperature difference on the lower half of the engine while the upper half is more nominal.
Increasing the engergy transfer around the spark plug hole I believe will yeild more results than not.

Something else to consider is that the cooling of the combustion walls is not necessarily the root cause of the problem. I'll have to do some research into the material properties when I'm back home, but could it be the atomic structure of the materials developing fissures over time due to heat cycling? For instance would voids and imperfections in the casting develop the same event?

Originally Posted by TitaniumTT

It seems to me that the stain is in line perfectly with the fin. It appears to me that the fin has kept that area from growing. Effectively retracting it as the rest of the housing grows. Looking at the 16x and the renni, they seem to aleviate some of this material. I'm wondering if this is in an attempt to not contain it, but to let it grow a the same rate. Thoughts?

It's a possibility, but has anyone actually analyzed the stain itself? Do we assume it's a discoloration of the Chrome lining or do we know if it's a Carbon impregnation of the Chrome? Additionally do we know how deep the discoloration is within the Chrome? I ask as that--I believe--will dictate the environment and conditions of the failure. If it's a discoloration of the Chrome caused by too slow an energy transfer through the matrial adjusting the cooling will help, if it is a thermo-mechanical interaction that causes the issue, perhaps modification to the cooling passages to allow easier expansion and contraction would help. From what I see thus far it's a lot of conjecture--can anyone do this testing?