Interesting effect of valve coking

[XfireZ51]

This was displayed in a thread on the C7 forum discussing issues w Direct Injection and effect of not having fuel sprayed on valves.
The dyno chart demonstrates the gradual loss of power over time. I suspect something like this may also happen if you're not using ur secondaries very often especially since oil fumes are quite present in the LT-5 air intake.
The third and fourth run show difference in same motor after de-coking of valves. Fairly dramatic.

http://i1083.photobucket.com/albums/j392/tech17/dynochart-thumb-valvecoking_zpslar1loyj.jpg (http://s1083.photobucket.com/user/tech17/media/dynochart-thumb-valvecoking_zpslar1loyj.jpg.html)

[XfireZ51]

Informative YouTube

http://youtu.be/7Pz0zTQ1bz0

[XfireZ51]

Also very interesting comments in this vid regarding effect of oil in throttle body


http://youtu.be/Mk4e5XFe47A

[Paul Workman]

And, another video on YouTube is "Oil Catch Cans: Myth or Must Have?"

I'll save you some time... They're a MUST HAVE, especially high rpm as in WOT or engine braking.

One of the (several) striking things I see as result of deleting my SPTs is the lack of coking on the intake valves; second only to steam cleaning.

As also mentioned in the video (first one) the amount of oil ingested and thus coking (I surmise) is reduce by 90% as result of the oil level being down almost/about a quart. True, the motor in the video was a modern LT1 w/ dry sump (read: different animal), but this is also true of the LT5s far as oil dumping into my catch can when the dipstick level is at the FULL line.

Windage/frothing is probably the culprit. So, I wonder what harm there is to maintaining the oil level as some point below the "FULL" line; say at the bottom 1/3?

Or, should I not worry about it, being fooled into thinking all is well because I have a catch can in place (on my 90, at least, and soon on the 91 too)? I'm leaning in favor of the catch can. I guess the question is, just how efficient is it, i.e., does it capture just a token amount of oil, or is it really very practically removing it "all"? Which can(s) are most effective?

[XfireZ51]

Justa point of clarification

The dynos are of a BMW 3 series, not LT1, but its indicative of a motor w DI.