Steve, I guess we were typing at the same time.

But now ? Isnt it because of the Vacc in the lower that you have to plug some of the oiler bores in the block ??????

Thats what if been told and doesent it make sence ,,,,,because otherwise the Vacc will suck the uper and you will actually not have enuff oil in the motor wile running?

And therefor you need to take the engine appart ?

Because if you have a supercat drysump motor and wet-sump it like i did you need to open those holes up,,,,,,,so why wouldent you close them when you dry sump a wet sump motor ????????????????

the short answer is no . the oil system is an open loop. on the wet sump version, pressurized oil is delivered to the filter IN thru a dedicated passage. it is then delivered TO the motor thru the center port of the filter housing.

now

if all you do is deliver oil to the CENTER port of the filter housing
from an external pump and then scavange the pan, all you are doing making the wet sump oil INLET in the block redundant ... it will see no flow. there a dozen ways to do deal with this all simple and easy and a lot of them bolt on. but there should be no passages that need to be blocked. and the vacuum will have no effect on oiling ( assuming i understand your question) because there is no differential pressure inside to cause any issue. the whole vacuum idea started a long time ago in winston cup when people discovered that running extremely light ring tensions would make big power but would also make huge blowby and LOSE power... sealed crankcases with vacuum allowed very light tension with no combustion chamber contamination...

it works. there is no question about that. but it isn't simple to get right and is not a case of " more is better" and in the vast majority of cases where ultra light ring tensions are impractical because no one wants to be rebuilding their motors all the time, the whole vacuum deal is more a freebie by product rather some reason to spend 5 grand on an oil system.

There are no holes to be plugged!!!
If you have any sort of breather in the valve cover, you will not pull vacuum until very high rpm. You definitely don't want the pump to pull vacuum if you don't have piston oilers. It will suck the wrist pins dry.
There is no way a dry sump pump can suck the oil from the top end of the engine if you have any sort of breather in the valve cover.

Great thread!! How about maintenance on dry sump system? How long between pump rebuilds and how much? Same with the pump belt? A broken or thrown belt would be catastrophic!!! Does that happen often?! Do you replace ever yr or 2? How much are they?

Great Thread, and thanks Eddie for all the info. I am looking to build some 800+ hp NA motors for a future project and I am leaving no stone unturned in the search for maximum reliable power. I have been looking into a vacuum pump, but it sounds like this is a much better way to go. Can you give us a ball park price on a 5 stage dry sump system as I am still interested in those advantages.

Bringing this back to the top...

With a dry sump system is it possible for the oil to drain into the engine if sitting for a day? If so what would be the best way to eliminate this issue? I don't want to put valves on the tanks...have heard horror stories about that. I suspect that the oil is syphoned out of the reservoir until it is the same height within the engine as in the tank. Is it best to rig the dry sump tanks so that the resting oil level would be only a couple of inches of oil in the bottom of the pan if sitting for a while? As soon as the engine is turned over the scavenge pumps would drain the pan...

Another concern is the vent out of the dry sump tanks going to a puke tank, drain valves to remove moisture/settled oil vapour. I have heard guys running the vent lines back to the intake so the engine will inhale the fumes. I have 4.5 l whipples and am not crazy about running a line to the hat...but when you shut down after a run you can definitely smell the oil vapours...makes me want to pop the hatch all the time to make sure everything is alright...
Does anyone run a air/oil separator and drain the oil from it back to the reservoir or is it best to catch it and drain every so often?

Any insight to these 2 issues?