thomas4age
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| posted on 20/12/06 at 08:49 AM |
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dry sump scavange pumps
Hey all,
I'm thinking that I might need to dry-sump the lexus V8 to gain enough clearance.
there's a few questions on my mind,
How does one select the right size and number of scavange pumps in an application.
and exactly how does a scavange pump do it's thing, I heard in the other topic that a scavange pump sucks an oil/air mixture, so surley when the
scavange pumps are to big they will suck the engine bone-dry, at which point the pumps would suck more air than oil, But isn't that exactly what
kills an oilpump?
I'm not going to race the engine so no need for a superspec set-up, I will defenatly use the stock presure pump which is in the block now,
I've never heard any fail even in some seriously HP situations.
grtz Thomas
[Edited on 20/12/06 by thomas4age]
If Lucas made guns, Wars wouldn't start either.
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bilbo
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| posted on 20/12/06 at 09:03 AM |
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I've not used a dry sump before, but the way I understand it, the scavange pump sucks oil and air into the top of a storage tank (basically a
remote sump), a second part of the pump (or a seperate pump) then takes oil from the bottom of this tank to feed the engine. Shouldn't matter
how powerful the scavange pump is provided its powerfull enough to keep ahead of the oil flowing into the sump.
HTH,
Bill
---------------------------------------
Build Diary: http://bills-locost.blogspot.com/
Web Site: http://locost.atspace.com
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Syd Bridge
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| posted on 20/12/06 at 09:17 AM |
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There's an interesting thread on ozclubbies about building your own dry sump system.
Cheers,
Syd. 
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thomas4age
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| posted on 20/12/06 at 09:21 AM |
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have you got a linky of that thread perhaps?
grtz Thomas
If Lucas made guns, Wars wouldn't start either.
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Wadders
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| posted on 20/12/06 at 09:49 AM |
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Here you go Thomas
http://www.oz-clubbies.com/phpBB2/viewtopic.php?t=4975&sid=9a0d393578595feb52a8342cae2b66ca
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MikeRJ
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| posted on 20/12/06 at 10:02 AM |
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Are the comments about a scavenge pump taking several HP to drive really true? I know they are fairly high volume pumps, but the pressure difference
between the sump and the oil tank must be quite low.
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thomas4age
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| posted on 20/12/06 at 11:31 AM |
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can't believe that part either,
because when I for instance take a pump to suck dry the seller after floods which happened on more than one ocassion at my grandads house even at
1.5KW effective power (2.5 taken from outlet) that would be enough power to shift the oil capacity of the engine around for about 10times a second.
so I do believe that some serious power must be in order to drive the scavange system I don defenatly not believe that it takes that much.
So I'm absolutly not going to take out the oil-pump out of the engine, I might look up what a set of gears cost from toyota/lexus and yank 2 in
cascade and have a housing made-up.
grtz Thomas.
If Lucas made guns, Wars wouldn't start either.
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mark chandler
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| posted on 20/12/06 at 01:39 PM |
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They recon that the power taken by the scavange pump more than equels what it saves in a good set up.
A decent system will provide additional power if sized correctly.
Normal engines have a lot of oil hanging on to the crank (up to 1 litre) and getting stirred up, all this wastes power so you need to employ a set of
scrapers to capture this and through into the sump.
Also by having negative vacumn in the crankcase means less energy is wasted with pistons pushing air around.
It all adds up, making a set of scrapers with a sump is a good idea if you are keen enough worth a few horses.
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