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Old 07-31-2019, 04:11 PM   #1
Dammit
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Default Oil pump as scavenge pump = death?

I'd like to convert to dry sump, one way of doing this would be to modify the existing oil pump so that it pulls oil from the sump and routes it directly into the dry sump tank, rather than the oil filter and from thence back into the engine.

Question is, is a pump a pump, or is a scavenge pump physically different from a pressure pump, and trying to use one in as the other will lead to RUD?
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Old 08-01-2019, 09:53 AM   #2
Dammit
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And the answer is: pressure pumps use intermeshing gears, as a constant linear pressure is required, scavenge pumps use either a gerotor or pair of Roots type wheels as they prioritise throughput over smoothness, and will shift more air/foam/oil but in a very jerky manner.

Therefore I need to adapt my design somewhat.
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Old 08-01-2019, 10:38 AM   #3
c.slopsma
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Would be interested in seeing what you come up with. Any teasers?

Would it be an idea to add a scavenge pump to fill the tank and route the oem one as a pressure pump fed by the tank. Tank>pickup tube.
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Old 08-01-2019, 11:09 AM   #4
Dammit
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This is (apologies) not for a Volvo engine, it's a water cooled Porsche engine (M96). Happy to elaborate, but don't want to sell you a dummy as it were.
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Old 08-06-2019, 10:14 AM   #5
Dammit
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Nothing to see here.

Last edited by Dammit; 08-06-2019 at 05:46 PM..
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Old 09-03-2019, 07:09 PM   #6
Dirty Rick
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For a pancake motor I would want a minimum of 4 stages of pumping.
1 for pressure feed, 1 for each head (2), and 1 for the sump.

I don't see why you could not use the factory pump as a scavenge stage, however,
The factory pump is sized as a feed pump, a scavenge stage is usually twice the size of a feed pump.
Remember Scavenging is part of the dry sump advantage, you suck out way more than you pump in.
This creates a vacuum in the crank case which dramatically improves ring seal and reduces oil leaks to zero.
In fact if you want to get serious about this aspect, you put the oil seals in backwards so air does not get sucked past them.
Note! you can make too much vaccum, we had a real nice superlightweight set of valve covers made for Dick Landy in his pro stock days, that sucked down on top of the rockers on a test run!
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