> I have been debating the merits of blocking off my oil filter by-pass.
I think it's a bad idea. I know just enough about pumping stuff with
positive displacement pumps to really confuse myself, but generally it takes
a lot of power to run a pump at very high pressure. According to some old
literature I have on oil pressure you need about 7 pounds per 1000 RPM.
Don't remember where that came from, so don't assume it's gospel. A TR3/4
oil pump in good shape with all the other bits working well delivers about
100 pounds pressure or more with the bypass cranked all the way down--I
assume it's still bypassing some. That's taking a lot of HP and putting that
skinny little pump drive shaft in jeopardy, even if you've removed the
stress risers and relieved it.
some of the theory bouncing around in my undisciplined head says the more
volume you blow through a postive displacement pump, the more work it does,
so the bypass shouldn't matter. But a simple practical experiment that I do
every time I rebuild an engine tells me that's not so. I use a drill and
shaft to spin the oil pump and pre-lube the engine (and pressurize the
accusump). When I'm doing this I play with the bypass--you can just about
stop the drill by cranking it up. For fun (okay, that's weird) I put a big
3/4 HP drill motor I have onto the shaft and got it up to 70 pounds. I had
to use a long bar over the side-brace to hold the drill.
So my thinking now is, enough oil pressure to meet requirements, and no
more. I rev my engines to 6.8K (maybe a little more when Cameron Healy is in
front of me), so I need fifty pounds. Call it 70 for good luck and that's
what I do. From the looks of my engines it's not a bad thing.
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