Quote:
Originally Posted by Homeoboxter
I agree with you on that it was a stupid idea in the first place to put a sealed grease-filled bearing onto one end of an air-sealed tube that allows for vacuum building up which forces the oil into the tube through the bearing. The other smart step by Porsche was to replace the dual-row bearing to a much weaker single-row that`s clearly undersized for this application. It`s just plain stupid. IMHO if they had stuck to the original dual row design with no seals (bc the IMS is literally swimming in oil and not lubricated by vapor or splash) the IMS failure would not exist. Like in the newer engines with the irreplacable bearing, which is larger (well-sized for the job) and works just fine with removed seals.
However, your example got me thinking and I `m tending to think the hybrid-ceramic is not the way to go either. (I know, your example is just n=1, but LN states none of their bearings ever failed, which is strange, because then why did the come up with another solution?). I`m saying this after I already put a hybrid-ceramic into my IMS... These bearings are best for high temperature, high rpms and minimal radial impact, like turbines. None of these conditions really stands in the crankcase. But, the IMS is exposed to a repetitive radial impact at high frequency due to opening the valves. Eventually due to this impact the ceramic balls that are much harder may wear the steel race prematurely. Interesting paper on the topic, just FYI:
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050175860.pdf |
Thanks, I will take a look. I guess with the IMSB, Excellence Was Excepted, Cost Accounting was Accepted.
PS those RND engines use the RND roller bearing- “It’s A Matter Of Thrust” they say in their ads, and RND is another Charles Novarro company. My point being they came up with even another solution and decided to use that in the rebuilt engines they offered for sale. And while my IMSB failed it’s impossible to know why at this point. I don’t think anyone else who has one installed in their engine needs to feel that the world is now ending.