Quote:
Originally Posted by Smallblock454
Vented sounds interesting.
If you consider that the IMS is a sealed tube, and that the air gas volume inside is constant, you'll have a very different air overpressure at let's say 10 degrees celsius and 110 degrees celsius. At the same time you'll have a constant underpressure of around −2 mbar in the engine. Does anybody know the inner volume of the IMS tube, so we can calculate the air overpressure at different engine temeratures?
This might also be a cause why the OEM IMS sealing is stressed by temperature change.
The term vented is used as ventilation i think. How does that work? Because if you do not use a sealed bearing the pressure in the engine should be the same as in the complete engine. Or am i wrong?
PS: sorry that i use the metric system.
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You've got the point. I made this video a year ago
https://www.youtube.com/watch?v=qzHwWUgU37k
There are 7 short ( 2 minutes or so) videos detailing precisely what you are saying, and showing how I approached this problem. I'm at just about 3000 miles since I made this simple modification to the IMS and all is well. I redline just about every day because it is fun. Click on my name under the video if your interested in seeing what I did. There's been an implication that Porsche blew the bearing design by overloading it. I have a hard time buying that unless the mistake was assuming grease in the bearing instead of oil when doing the load calcs. That is part of the reason I went back with a
sealed high temp (high temp grease and Viton seals) greased deep groove steel ball bearing with a vented IMS. The other reason is that the fully sealed bearing feature coupled with venting keeps any trash in the oil out of my IMSB.