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The pcv is designed to evacuate the crankcase right! How does the mighty mouse do this with a filter to the outside air in-line between between the dirty side and clean side. I have a oil separator hooked up like this minus the filter. Can someone please explain this to me
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Originally Posted by grpweld
The pcv is designed to evacuate the crankcase right! How does the mighty mouse do this with a filter to the outside air in-line between between the dirty side and clean side. I have a oil separator hooked up like this minus the filter. Can someone please explain this to me
visualize our filter top as a third one way port that opens any time more flow enters the can than is able to be drawn off by the intake manifold.
Forgive me, as maybe this has been discussed...and I am interested in a system for my NA 08' C6 Z06.
With the dry sump oil system on the LS7, it is essentially a vacuum pump on the crankcase. Wet sump engines are not this way.
So, the crank case pressure at the valley port should be pretty low at idle, and probably close to zero or negative at high RPM because of the scavenging action of the dry sump pump.
Is the valley port lower pressure than the intake manifold vacuum at idle? Not sure, probably depends on the camshaft, but the intake system may draw oil in at idle with a big cam, because the intake is lower pressure than the crankcase.
At WOT we know the intake pressure is close to zero, but the valley may be low as well since the dry sump pump is spinning fast and is pulling oil and pressure out, however piston/rig blow by is high.
The factory dry sump tank is essentially a giant catch can/oil separator/reservoir in itself, that is its purpose.
If the object is to keep oil out of the intake system, why wouldn't I just cap the intake port and the valley port, and let the dry sump pump scavenge the crank case, and let the dry sump tank do its job?
I am not convinced the differential pressures between the intake port and the valley port, with a dry sump oiling system justify a catch can separator system.
What is the risk of just blocking off the two ports?
all of the air pulled from the bottom with the oil comes back into the engine at the top. it is not a one way trip, also disabling the pcv system has its pros and cons which i suggest you look into
Originally Posted by SG4247
Forgive me, as maybe this has been discussed...and I am interested in a system for my NA 08' C6 Z06.
With the dry sump oil system on the LS7, it is essentially a vacuum pump on the crankcase. Wet sump engines are not this way.
So, the crank case pressure at the valley port should be pretty low at idle, and probably close to zero or negative at high RPM because of the scavenging action of the dry sump pump.
Is the valley port lower pressure than the intake manifold vacuum at idle? Not sure, probably depends on the camshaft, but the intake system may draw oil in at idle with a big cam, because the intake is lower pressure than the crankcase.
At WOT we know the intake pressure is close to zero, but the valley may be low as well since the dry sump pump is spinning fast and is pulling oil and pressure out, however piston/rig blow by is high.
The factory dry sump tank is essentially a giant catch can/oil separator/reservoir in itself, that is its purpose.
If the object is to keep oil out of the intake system, why wouldn't I just cap the intake port and the valley port, and let the dry sump pump scavenge the crank case, and let the dry sump tank do its job?
I am not convinced the differential pressures between the intake port and the valley port, with a dry sump oiling system justify a catch can separator system.
What is the risk of just blocking off the two ports?
Forgive me, as maybe this has been discussed...and I am interested in a system for my NA 08' C6 Z06.
With the dry sump oil system on the LS7, it is essentially a vacuum pump on the crankcase. Wet sump engines are not this way.
So, the crank case pressure at the valley port should be pretty low at idle, and probably close to zero or negative at high RPM because of the scavenging action of the dry sump pump.
Is the valley port lower pressure than the intake manifold vacuum at idle? Not sure, probably depends on the camshaft, but the intake system may draw oil in at idle with a big cam, because the intake is lower pressure than the crankcase.
At WOT we know the intake pressure is close to zero, but the valley may be low as well since the dry sump pump is spinning fast and is pulling oil and pressure out, however piston/rig blow by is high.
The factory dry sump tank is essentially a giant catch can/oil separator/reservoir in itself, that is its purpose.
If the object is to keep oil out of the intake system, why wouldn't I just cap the intake port and the valley port, and let the dry sump pump scavenge the crank case, and let the dry sump tank do its job?
I am not convinced the differential pressures between the intake port and the valley port, with a dry sump oiling system justify a catch can separator system.
What is the risk of just blocking off the two ports?
The stock single stage scavenge pump is not going to create a vacuum. It takes a min of 4 stages to get a vacuum on a large cubic inch engine.
Nice car! Sounds great. I also had a ws6 T/A, liked it a lot. Jealous of your big garage!
I haven’t seen the inside of your can but I strongly suspect with that filter on your can you are introducing unmetered air into the engine. Have you seen a lean cel or have you scanned it and noticed increased fuel trims? Also, because of that filter you have eliminated the Positive Crankcase Ventilation, because the engine will draw clean air from the filter rather than drawing on the crankcase...I personally like drawing the PCV to burn the blow by which keeps the engine clean inside, eliminating sludge.
This is deja vu for me....I used to run a filter style can and had that problem, my oil got black in no time, I got a po174 lean code plus the filter would let oil smell get into my HVAC inlet right by where your can is. I swapped to a can with no filter which took care of all problems - if you get these problems you might try replacing the filter with a plug.
Our systems are hybrid open and closed based on demand in the system.
Originally Posted by Joe_G
Nice car! Sounds great. I also had a ws6 T/A, liked it a lot. Jealous of your big garage!
I haven’t seen the inside of your can but I strongly suspect with that filter on your can you are introducing unmetered air into the engine. Have you seen a lean cel or have you scanned it and noticed increased fuel trims? Also, because of that filter you have eliminated the Positive Crankcase Ventilation, because the engine will draw clean air from the filter rather than drawing on the crankcase...I personally like drawing the PCV to burn the blow by which keeps the engine clean inside, eliminating sludge.
This is deja vu for me....I used to run a filter style can and had that problem, my oil got black in no time, I got a po174 lean code plus the filter would let oil smell get into my HVAC inlet right by where your can is. I swapped to a can with no filter which took care of all problems - if you get these problems you might try replacing the filter with a plug.
I haven’t seen the inside of your can but I strongly suspect with that filter on your can you are introducing unmetered air into the engine.
Sounds like you don't have a clear understanding of how the MM can works. The filter sits on top of a check valve which allows excess blowby gasses out, but nothing is allowed in.
Check out the Mighty Mouse website for lots of information on different crankcase ventilation systems and catch can setups
Sounds like you don't have a clear understanding of how the MM can works. The filter sits on top of a check valve which allows excess blowby gasses out, but nothing is allowed in.
Check out the Mighty Mouse website for lots of information on different crankcase ventilation systems and catch can setups
If you turn the MightyMouse filter upside down and look into it, you will see a large rubber disk ... This allows excess built-up crankcase pressure during WOT operation to exit through the filter, but does not allow air to enter into the filter (and catch can) during normal operation.
Filtered outside air is pulled into the engine's crankcase via the small hose attached in the rubber accordion bellows just downstream of the engine's air intake air filter ... not through the filter on top of the catch can.
If you turn the MightyMouse filter upside down and look into it, you will see a large rubber disk ... This allows excess built-up crankcase pressure during WOT operation to exit through the filter, but does not allow air to enter into the filter (and catch can) during normal operation.
Filtered outside air is pulled into the engine's crankcase via the small hose attached in the rubber accordion bellows just downstream of the engine's air intake air filter ... not through the filter on top of the catch can.
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This is how my catch can works, filtered input to the valve cover via the factory port on the air filter bellows, PCV draw on the valley port via the port behind the throttle body, catch can between the port behind the throttle body and the valley port.
I couldn’t see the one way disk on the filter/can combo that the OP has. That will take care of the problems I listed, except for the release of oil vapor into the HVAC intake, but I would suggest that is rare and not really an issue. Without that one way disk, you’ll have the issues I listed, I know from experience.
If you don't use the MightyMouse catch can (with the filter on top), this is a good way to plumb another catch can that don't have that filter on top of it >>
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Dirty crankcase fumes are sucked in from the valley cover barb and into the catch can
Then the 'cleaned' crankcase fumes are pulled into the vacuum port of the intake manifold (on the intake side of the throttle body)
Of course this air needs to be always replaced with clean fresh air .. which is provided by a filter in the valve cover.
During idle and normal part throttle operation and cruise, there will always be vacuum to keep a steady flow of fresh air throughout the crankcase and into the intake manifold (of course 'cleaned' by the catch can).
But, if under full throttle operation (especially in high HP engines) there can be a situation where pressure tends to build quickly in the crankcase due to piston ring blow-by ... this excess pressure is relieved through that filter in the valve cover (saving crankshaft seals).
The baffles on the ls valve covers work pretty well. You're not cleaning up anything by capping that clean side port and running fresh air to atmosphere. Sure it works with some tuning, but why not just grab some metered air from an already filtered area of the air intake?
Here is a photo of inside the valley pan crankcase tube. You will see it is not really a 3/8 tube but a 1/10 of an inch restrictor. Based on a .100 hole orifice chart and say a few psi you are lucky to get a few CFM and same goes if you have 18 inches of vacuum just few CFM. A majority (like 80%-90%) of the blow by at WOT is handled by the valve covers which can go to the air and or the intake bridge. Also big cam guys don't have a lot of vacuum and the .100 hole is not enough for the PCV that is why on the 454 LSX motor you buy from GM they have 2 dirty side ports one from the valley cover and one from the back of the passenger side valve cover. Another reason for the valve cover port is that it cleans out the air from the back side of the engine. With the big cam you are lucky to pull 60% of the air in as a stock motor with 16 inches of vacuum along with the higher power level (more blow by) you need another dirty port. A typically PCV system will flow 3-4 cfm at idle. With the old pintle valve system it was done/adjusted automatically. Basically the LSX valve passenger side valve cover has a .100 orifice in it also. So the 2 of them make up the dirty side of pcv system. The instructions you get from GM on the motor are 3-4 pages with a 1/2 page covering the PCV system. Big cam cars - Pull your clean side hose and put a .100 restrictor in it and you wills see how little it flows.
