How much vacuum can an LS7, dry sump, oil pump draw?
01-23-2007, 01:17 PM
#1
How much vacuum can an LS7, dry sump, oil pump draw? I'm thinking of building an LS2 stroker with an LS7 dry sump system. I understand that the amount of vacuum created changes the piston ring package. Anybody know what kind of vacuum it's capable of drawing? Are there any internal changes to the engine that can/should be made to increase the amount of crank case vacuum?
01-23-2007, 03:53 PM
#3
It looks like the scavenge pump is thicker than the supply pump. How many times thicker would it have to be in order to create vacuum? 1.5X, 2X...?
I once saw an external, bolt on, bottom mount, dry sump pick up, but can't find it again. Any one know what I'm talking about, and/or who makes them?
http://i69.photobucket.com/albums/i7...ayS4020357.jpg
I once saw an external, bolt on, bottom mount, dry sump pick up, but can't find it again. Any one know what I'm talking about, and/or who makes them?
http://i69.photobucket.com/albums/i7...ayS4020357.jpg
01-23-2007, 09:07 PM
#4
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The pump required for any engine is a function of HP and ring seal. The general rule I have found to work is 4 cfm per hundred hp. If you set up your pump to move this amount, you should have decent vac in the crankase.
There are external pumps that just scavenge that mount in place of the AC pump on the LS engines. You can see these pumps on our website in the online store under engine-oil system-dry sump kit.
If you need larger capacity pump for a high hp build we can spec a pump that has worked for us in high hp turbo engines, it features a high speed lobe design and can only be used in scavenge applications.
Kurt
There are external pumps that just scavenge that mount in place of the AC pump on the LS engines. You can see these pumps on our website in the online store under engine-oil system-dry sump kit.
If you need larger capacity pump for a high hp build we can spec a pump that has worked for us in high hp turbo engines, it features a high speed lobe design and can only be used in scavenge applications.
Kurt
01-24-2007, 07:29 AM
#5
This is a recent LS7 startup. Engine is wetsump using LS2 pan and pump. In that the valley cover has no vent we ran valve cover vent to intake port. Crankcase holds serious vacuum even after shutdown.
Now added the tank below which has a check valve under breather filter. So- holds intake/crankcase vac in tank and vents via check valve if pressure builds. Still in experiment stage:
Now added the tank below which has a check valve under breather filter. So- holds intake/crankcase vac in tank and vents via check valve if pressure builds. Still in experiment stage:
