Jason - I have nothing to contribute to this thread other than a bump. Hopefully the collective mind here is able to figure this out.
. You know, you should make a Road trip North for the Summer-
Alright guys help me out here. I know some others have put some work into figuring this out??
Back to topic at hand. So I hooked up some clear hose to the 3/8 coolant return running from the upper right corner of the radiator back to the Degas running a loop up past the bottom of the windshield so I could see exactly what was happening the results were intriguing.
My coolant system has been flushed for several hundred miles so there shouldn't be any air in the system.
Normal cruising doing about 75 at just under 2000rpm is exactly as expected- Constant steady flow of coolant with no air. This did not appear affected by load or boost. I was able to reach about 28psi before she would shift down. And that is when things became interesting. Tangent- I bloody hate these damn Transmissions. Impossible to control gears unless I want 3rd. After flowing solid coolant for miles, I would hit the gas making it shift down and about 5-10 seconds later I started getting tons of very small air bubbles flowing past my view. This continued as long as I was able to hold the RPM at 2500rpm or above. Not sure if this is being created from cavitation, or from air being pulled into the system somewhere. These results were very consistent. Anytime I revved the motor, I got air. This does not appear to be load related, but I wasn't towing anything so can't be certain
At idle, there is no flow at all through the hose. In fact I did see some reverse flow where Air was going from the Degas to the radiator. Everytime I would take off from a stop there was an enormous amount of air being purged back to the Degas bottle. These results are a bit ambiguous right now as my time to experiment is limited.
I did have a pressure gauge connected as well, but that never budged much. But I am curious to know, what is causing the flow that is obviously RPM related. Is there a low pressure on the inlet hose pulling fluid, or a high pressure at the outlet pushing fluid back to the degas bottle. Does it matter?
In some of my reading about cavitation(maybe it was the NPSH) I remember something about not enough pressure at the outlet of a pump, or too much restriction at the inlet. FWIW, my coolant temps are stable at 197. Could a low pressure at the inlet be artificially reducing the boiling point enough to induce flash boiling(cavitation?) causing the miniature air bubbles I was seeing?
Is anyone even paying attention?