Opinions will be appreciated.The application is 612 cu.in.,supercharged with a 6,000 rpm rev limiter.The pump is capable of producing 15 inches of vacumn.The concern is;should we use breathers or seal it up?If it is sealed and a piston burns,where will the fuel go?The boost will range from 5 to 8 pounds,subject to the quality of fuel.The oil tank is 4 gallons with a breather.Thanks for any comments.

Use breathers.That amount of vacuum will deny the wrist pins oil and will wipe out eventually.With breathers you will lose the power made by that vacuum created by the 5 stage pump,but the engine wont suffer.If the engine had piston oilers,it would be a different story.

Thanks JCPERF,These are new engines we are building.Piston oilers are being used.In fact,that is another issue:should the orifice size be .028 or .040? The wrist pins are DLC coated and the piston domes and skirts are coated.Also,the valve covers have spring oilers and we have sprayers for the solid roller lifters.However,if we use the lifter sprayers a screen will be fitted over the sprayer bar.Unless we were to not use a screen the closed scavange would over come screen restriction.Also,we have jessel belt drives.

.028 is sufficient for the piston oilers.I would say you could go bigger but you are using spring oilers too.Are you scavenging out off the lifter valley?

Jc The Keyboard Just Froze Up ~bear With Me We Are Not Seperately Scavenging The Lifter Valley And Honestly Do Not Know How The Comment Has Been Heard ~use Bigger Nozzle Openings In Dry Sump And Smaller In Wet Sump~mike At Blp May Have A Breather That Sees Pressure Change And Opens When A Piston Would Burn~we Also Have Lifter Bore Bushings

You can go bigger with the piston oilers with dry sump.You can change the spring in the oil pump to compensate for the pressure drop.When you have to many sprayers[piston,valve spring] it creates a major pressure leak, so you have to sometimes[when your engine clearances are loose] change the pump bypass spring to a stronger spring.

The point is well taken~there is only so much volume available before it effects something else~probably leave the valley sprayers out~still concerned about creating a bomb if a piston burns when the sump is sealed except for the tank breathers~

It will just fill the dry sump tank breather if you burn a piston.Or it will push a pan or intake endrail gasket out

If spring oilers are not used can a .040 piston oiler be used then or should it stay at the .028 size?

Johnny,it is my understanding that dry sump vs.wet sump is a big part of the answer to your question.The wet sump has more oil coming off from the crank and therefore, gets that oiling benefit.The dry sump pump may be capable of more volume of cleaner oil.The spring oilers and .040 sprayers should work together in a dry sump system.