Exhaust Vacume question

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madmax/6

madmax/6

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I installed the Morroso exhaust valves into my headers and ran the hoses to my valve cover.I thought the whole purpose was to create vacume so I have a closed cover.A fellow racer said I need a breather in the cover to allow air in,,,thought that I was trying to create vacume??I think it should bee sealed so it would suck crankcase pressure.Thoughts and guidence appreciated.Guzzi Mark
 
well...it can still suck air thru the dip stick tube....

i agree with you...take off the extra breathers
 
Mine did not come with instructions,The instructions I have read dont address anything about a breather or a cap that should or shouldnt breath.I googeld and read alot before I posted the question.Bottom line,,YOU dont know either.Thanks for your words of wisdom.
 
madmax/6 said:
Mine did not come with instructions,The instructions I have read dont address anything about a breather or a cap that should or shouldnt breath.I googeld and read alot before I posted the question.Bottom line,,YOU dont know either.Thanks for your words of wisdom.
Click to expand...


I had them on my car. 1 breather in each valve cover. Each breather had a tube for a hose. Each hose ran down to a valve in each header.

Systems like this don't do much at low speed. That is why you don't want a sealed system.

http://www.summitracing.com/parts/MRG-6002/


Moroso is the same thing.

http://www.summitracing.com/parts/MOR-25900/
 
you need a vent somewhere or youre gonna suck trash in thru the seals. The pan e-vac kit has one way valves that open when the exhaust pulls a negative pressure. gotta pull air from somewhere to keep the crank case fresh.
 
You ought to have at least some air entering the crankcase to sweep it clean and prevent dirt ingress past shaft seals. How to set it up depends on how tight a ring seal you've got (i.e., how much pressure there is in the crankcase). Be careful how much vacuum you create in the crankcase. Too much and you'll suck in the longer gaskets (oil pan, valve cover) and create oil leaks. You may want to put it together with the inlet breather(s) blocked off, rig up a vacuum/pressure gauge to look at the crankcase, make some test passes and see what the crank pressure is doing. If it's going way into vacuum, you can lessen the vacuum by means of a calibrated air inlet to the crank. Not too hard to rig this up if you think about it.
 
From what I have read,,,this type of system creates vacume at lower rpm,and not much above 4000rpm,and at best 3 to 6 .I go to 6200 rpm on a run.The expensive vacume pump systems run between 10 to 15 constant.This is a drag only car so I think I want the top sealed with the sealed breathers that have the hoses going to the exhaust check valves in the headers.Thinking I will put a small open breather on my dip stick tube.Mark
 
With a breather on the valve cover I only got 1.5 vacume at idle and 2.5 at 3000 rpm.Sealed the cover and got 3 at idle and 5 at 3000 rpm.Vacume gauge sealed to dip stick tube.Will leave it hooked up and see what it reads going down the track at 6000 rpm.Thinking about a vacume pump cause I would like 10 neg pressure constant.
 
madmax/6 said:
From what I have read,,,this type of system creates vacume at lower rpm,and not much above 4000rpm,and at best 3 to 6 .I go to 6200 rpm on a run.The expensive vacume pump systems run between 10 to 15 constant.This is a drag only car so I think I want the top sealed with the sealed breathers that have the hoses going to the exhaust check valves in the headers.Thinking I will put a small open breather on my dip stick tube.Mark
Click to expand...

this sounds backwards to me. Seems higher rpm would pullmore vacuum on the valves and low rpm wouldnt open them much. I could be wrong but it seems like simple physics.
 
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