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i think its best to use the biggest hose u can 3/4'' is AN-12 or 5/8'' AN-10 should be fine so that u can evacuate the pressure and carry the least amount of oil with it, its not really working properly if it is the cause of the oil usage filling the catch all the time, its an air pressure relief and if it dosnt carry any oil but removes the pressure that is the best outcome, if ur just venting then use massive hoses, if ur to intake or vacuum then pick ur hoses to suit most volume flow (lowest airspeed) with least oil draw
 

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Discussion Starter · #84 ·
Are you using the boost check in the inlet tube line?

(and the PCV in the can on the snout line?
Boost check is to the supercharger inlet for vacuum. That pulls from the crank case (the valve cover).

The valve cover is 3/4" hose to the can. The third port on the wild MM can is plugged, but I have fittings to try the "Big Boy" variant if needed.

The other valve cover goes to the air intake for fresh air.



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I’ll need to review their site. I really thought the PCV valve was serving to prevent boost to the can and the Boost Check was for the inlet hose to prevent to going to the inlet…

ETA: as I have contradicted myself in this thread I am obviously not fully grasping the details. I will need to head over to MMS to try to gather up some knowledge.
 

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a boost check to vacuum on PD blower wont do anything as it wont ever have boost on it to close (more for turbo with pressure in intake) so u may as well just have it on vacuum all the time without the valve as it will always be sucking vacuum or intake anyway
 

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Discussion Starter · #88 ·
I’ll need to review their site. I really thought the PCV valve was serving to prevent boost to the can and the Boost Check was for the inlet hose to prevent to going to the inlet…

ETA: as I have contradicted myself in this thread I am obviously not fully grasping the details. I will need to head over to MMS to try to gather up some knowledge.
To be fair, the MM website is not intuitive or super helpful. You really have to dig around to figure out what the hell they're selling, beyond the buzz words like BOOST CHECK!!!

Also, regarding the B15 instructions. Note how the PCV system uses flow restrictions. On purpose.

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To be fair, the MM website is not intuitive or super helpful. You really have to dig around to figure out what the hell they're selling, beyond the buzz words like BOOST CHECK!!!
Also, regarding the B15 instructions. Note how the PCV system uses flow restrictions. On purpose.
The boost check AFAIK is a simple check valve. The PCV is (again, AFAIK), a variation on a check valve that allows flow toward the vacuum, but only up to a point and at some differential it closes flow to the vacuum.... and it's something that I need to grasp better (regarding MM's PCV design, specifically.)
 

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Discussion Starter · #90 ·
I was planning on doing a quick review on the can - I need go get pics up.

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I went back to MM's website and I'm not wrong in my grasp, only the names... and I'm potentially redundant in my application.

The MM WILD cans all come with the "Super center" along with the "Super boost check" exit fitting; that combination of pieces is what MM is calling the "PCV Control assembly" and what I called the PCV valve.

That assembly connects to the vacuum source (snout) and both allows flow toward the vacuum and apparently LIMITS flow in that direction under heavy boost.

I'm on board with that; makes perfect sense.

My concern is that the fresh air line from the inlet tube to the crankcase --- whether via a valve cover in your case or the valley in mine --- that line will flow towards the crankcase at cruise, admitting fresh filtered air. However, under boost conditions it will could then move dirty crankcase fumes toward the inlet, possibly with nasty results. That's what I want to prevent, so I ordered the inline check valve MM sells to go in the fresh air line. I mistakenly called it a "boost check" but it's just a generic check valve.
 

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Attached is a screenshot from my -B15 manual.
Note: all the stock ports are 3/8" View attachment 161938
Just some thoughts from reading this sub-forum:

Orifices would be related to engine volume as well as anticipated blow-by.

-build related info-
An attempt to quantify engine rpm here, for any given
engine volume (CID), might serve to be useful here.

Th B-15 lsX Engine is rated for 900fwHP by GM.

That would mean the GM Engineers felt it would be inhaling and consuming ~1350 CFM.

Again, orifice size will be dependent on individual builds. . . .

------------------------------------------------------------

Also, because of a post or two written in the last day or so:

If there is no vacuum used to vent the crankcase, then one would be attempting to use crankcase pressure to 'Pump' the blow-by out of the crankcase, and into the atmosphere. This is not an efficient way to do this. And if attempted with an engine using E85 as a fuel, will end up contaminated oil.

Good luck to all!
 
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also remember if u are using vacuum and a fresh air inlet that will be like just opening a hole in the manifold and u will have to account for it going leaner with unmetered air, and if that is too much the TB will be closing and timing lowering to try to keep idle where it should be, thats another reason i rather just use the intake before TB
 

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also remember if u are using vacuum and a fresh air inlet that will be like just opening a hole in the manifold and u will have to account for it going leaner with unmetered air, and if that is too much the TB will be closing and timing lowering to try to keep idle where it should be, that's another reason i rather just use the intake before TB
'Everything' must be metered 007..lol

Simple explanation for a closed system;
A Metered Vacuum pulls pollutants out.
A Metered Inlet allows for 'Sufficient' filtered & fresh air to replace, displaced pollutants within the crankcase.

This is why I have been attempting to get everyone to consider the size of their lines, orifices, etc.. :)

Some most likely already do understand.
But for those that don't. . . 'Pay Attention'..;)

And this is also why I believe a 2-Stage system should be considered.

-even though I have been told current 2-Stage systems use 2-PCV valves-
Considering that we can only stand on the 'Loud Petal' for so long, the 2-Stage system might(?) not have to be so highly regulated on the side which is fully opened during full on acceleration???. . . . .

Glad I never had to run one of these systems on any of my race cars..:mad:
 
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I also might add; on the track with customers and friends: using external vacuum pumps, we found best performance, with the least headaches, by using not more than 10 inches of vacuum.

Older VBS systems, which used the headers to pull the vacuum, pulled about 4". Even then, we had to turn the rear main seals around, or they would leak..lol
 
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The -B15 does not have separate instructions for NA and boosted crankcase ventilation, same set of instructions for both.

-B15 instructions state clean air from intake to passenger valve cover. Driver valve cover and valley to vacuum. Compared to the Cadillac setup, clean air from intake to both valve covers, and valley to vacuum.

Difference between the -B15 and LSA is higher profile baffled valve covers and a baffled valley cover. Not sure if the LSA has a baffle in the valley?

Both stock engines seem restrictive at higher power levels based on the ID of the ports and lines. Guess that's where consideration for increasing fitting and line diameters comes into play? Has anyone given consideration to increasing the vacuum port diameter, what effect it would have?

I'm close to going with the Cadillac setup based on the fact Cadillac was engineered specifically for supercharged application with no consideration for NA, must be some good reason?

Regardless, I have a catch can between the valley and vacuum. In addition, I installed a check valve OUT from the oil fill, thought it would be a good idea just in case too much pressure builds-up at WOT. Still have the stock 3/8" lines and fittings for now though.
 

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The -B15 does not have separate instructions for NA and boosted crankcase ventilation, same set of instructions for both.

-B15 instructions state clean air from intake to passenger valve cover. Driver valve cover and valley to vacuum. Compared to the Cadillac setup, clean air from intake to both valve covers, and valley to vacuum.

Difference between the -B15 and LSA is higher profile baffled valve covers and a baffled valley cover. Not sure if the LSA has a baffle in the valley?


Both stock engines seem restrictive at higher power levels based on the ID of the ports and lines. Guess that's where consideration for increasing fitting and line diameters comes into play? Has anyone given consideration to increasing the vacuum port diameter, what effect it would have?

I'm close to going with the Cadillac setup based on the fact Cadillac was engineered specifically for supercharged application with no consideration for NA, must be some good reason?

Regardless, I have a catch can between the valley and vacuum. In addition, I installed a check valve OUT from the oil fill, thought it would be a good idea just in case too much pressure builds-up at WOT. Still have the stock 3/8" lines and fittings for now though.
Good research and excellent info Kitty..(y)

The first two statements I highlighted above, tell one a lot about what the GM Engineers think about the production of blow-by in an NA Engine, versus an engine with Power Adders, such as a Blower.

Beneath those two statements, I Italicized and underlined other variables related to power adders / potential increase in HP. As HP goes up, so does the increase in pressures playing on the top of the piston. And so 'might' blow-by. These variables are also important to understand..;)

Today empirically, it seems most have determined that a Number -10 AN line appears to be sufficient to evacuate 1000 HP. But what if your only producing 750 HP. How far down does one need to downsize?

GM placed a 556 HP rating on the stock LSA.
GM includes a 900 HP 'Warranty' for the stock B-15.

Cheers
 

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Good research and excellent info Kitty..(y)

The first two statements I highlighted above, tell one a lot about what the GM Engineers think about the production of blow-by in an NA Engine, versus an engine with Power Adders, such as a Blower.

Beneath those two statements, I Italicized and underlined other variables related to power adders / potential increase in HP. As HP goes up, so does the increase in pressures playing on the top of the piston. And so 'might' blow-by. These variables are also important to understand..;)

Today empirically, it seems most have determined that a Number -10 AN line appears to be sufficient to evacuate 1000 HP. But what if your only producing 750 HP. How far down does one need to downsize?

GM placed a 556 HP rating on the stock LSA.
GM includes a 900 HP 'Warranty' for the stock B-15.

Cheers
I don't have the same level of experience you and others have that contribute regularly. I learn a lot through this forum and try to provide information I feel may be useful. The ventilation subject is on going, and obviously a thoughtful challenge to resolve, at least for me, I'm trying to better understand. It's not a glamorous subject for sure, think it is under rated by many. But if inadequate, rings and seals are at risk, and both require a huge amount of re-work to correct. I have not experienced blown seals to date. I did replace the rear main when I installed the new clutch.
 

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I'm still running 3/8" lines, routing configuration is stock. Just wanted to share a couple images of the 5/8" oil fill check valve OUT to atmosphere. This is installed just for insurance to relieve excessive case pressure at WOT, want to avoid potential blown seal condition.
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