quote:
Originally posted by Brian Barnhart:
Gary,
When you say pump relief, I assume you are talking about the oil pump pressure regulator valve that controls system oil pressure. Whereas the oil filter bypass valve is the one blocked on the subject engine.
It would seem to me that relative pressure drops across filter and engine would be fairly constant regardless of the state of the oil pump pressure regulator valve. Therefore, even in the scenario where the filter bypass is blocked and the oil pump regulator valve is stuck closed, system pressure would need to reach some huge number (hundreds of PSI) to create 70+ lbs. of differential pressure across the filter since most of the pressure drop would still be across the rest of the engine (bearing clearances, oil passages, etc.)..
Let's try it this way. Can we agree that "the engine is the engine"? Can we also agree that, aside from some minor issues ..that the pressure drop across the engine is directly related to the flow through it (assuming the same visc oil)??
So ..if 1gpm at let's say idle ..gives us 50lbs ...2gpm will give us 100lbs???
Now according to this ..the filter is next to nothing. Dwarft by the incredible resistance of the engine. You got that part ..I get that part.
Now, and this is ONLY for the sake of demonstratioin, just so I don't have to construct the REAL scenario,.....
..assume the relief is open ...it's @100.0001 psi and that 1 gpm is passing through the relief (assume that this threshold has been reached - the relief is set @100.00005)
So NOW we have 100.0001 psi applied ....1 gpm going through the relief ..and one gpm going through the filter and through the engine.
How much backpressure does the engine generate @1gpm??? 50lbs. This is the upstream pressure seen by the engine ..this is the downstream pressure seen by the filter.
So we have 50 lbs of backpressure from the engine and 100.0001psi applied. It is the pressure seen by both the upside of the filter ..and the pressure relief.
So the filter sees 100psi on the supply side ..and 50 psi on the demand side. It only sees 1gpm of flow.
So ..we see 50.001 PSID @ 1gpm flow to the engine.
Now blip the engine up to 6k and instantly apply 8 gpm into the "chamber" that exists between the upside of the media and the relief.
This is not a perfect example ..it's got it's flaws and needs a "lil help" ..and is not necessarily shared by all. It does satisfy my observations.
So ..you could say I watched something approaching the speed of a snail ...and then back spec'd Goldberg's theory of how I was related to snails.
[ June 23, 2006, 12:04 PM: Message edited by: Gary Allan ]