I've taken apart a motor that had a groove all the way around the iron face, due to solid corners. motor just lost compression.



these irons were lapped by Rick Engman.



I will not use solid corners again...they [atkins] are in my motor right now, almost 10k miles, 17psi, I pull 14in-hg at a 900 idle.

 

I'm planning on running solids on an N/A setup; but I'm going from FD springs back to the wire-style spring.



My guess is the decrease in spring-pressure will only lessen the chance of scoring the irons; but still do their job as well as needed... in an N/A setup anyway.

 

The corner seals with the insert seal better than solid ones. Also do not have a sharpe corner where cracks start easier.

 

Last week I was in DC for a conference on friction wear and lubrication and ended up talking to a Mazda engineer for a bit about the research that I am doing, anyway it seems that the rubber insert is not just to help compression but as a vibration damper

 

Interesting

 

Basically, excuse my lack of knowledge on this subject, the Mazda engineer feels that going with the stock corner seals is better and safer due to the small amount of play that the rubber insert gives them?

 

Im not 100% sure on what sort of vibrations it dampens or how exactly the rubber insert does this as it wasnt the easiest to talk in detail about it with someone who speaks english as a second language and as such the conversation never compared solid corner seals to the ones with the rubber insert I just thought that this was a reasonable thread to share this info. My personal feeling is that if you did a lot of testing you would probably find that in some applications the solid seals are better and in others the ones with the rubber insert are better.



When i say that im not sure what they actually dampen the rubber piece could be there to help stop the apex seal bouncing in and out of the slot and causing chatter marks on the housing or it could just be there to change a natural frequency of the corner seal system (which it will do even if this is not its intended purpose).

 

I haven't seen any engineering data but I've developed this theory through observation.



Engines that have lived calm sedate lives generally will have the rubber pieces intact even after many, many miles.



Engines that have seen much enthusiastic use never have the rubber pieces intact.



It doesn't seem to hurt anything to leave them out on a performance build. Philosophically speaking, they won't be there for very long anyway.



I am not sold on solid seals. It seems to me that the sharp corners in the slot are a perfect stress riser for a crack to form, while the non-solid type have a nice smooth radius on the inside.

 

I would say the rubber insert does not exactly limit "vibration" but rather "resonance" of the apex seal. due to the in and outward movement of the apex, the clearance of the apex towards the rotor groove and combustion resonance it will only be in a fixed position at both corner seals. Meaning that a solid seal (metal) will not temper the vibration ont the apex, where the rubber insert will do.



Remember why apex seals brake most often.. yes Detonation.. and what is detonation causing?? Right resonance -> resonating an (un)even pulse towards the apex seals and therefore breaking them.



See it like the glass of water that can be broken with the right level of resonance in the voice of a singer.



the rubber insert makes perfect sense, but will it still temper the resonance when it hardens?

 

Damn I didn't think anyone else knew this on the boards lol...