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With a closed system my crank case pressure was way to high. A vented can was the only option to keep the pressure low.
Well actually, there's a better system and that's what he's getting at.
The basic vented can is NOT ideal but it is VERY popular. Virtually EVERY catch can system out there is just that: Improved Racing/Dedicated Motorsports/Motion Raceworks, they ALL sell basic vented cans and sort of pretend theirs is the best and that's all you need.
The ACTUAL fix is offered by Mighty Mouse. Their "WILD" setup combines a valved-vented can along with a functional PCV valve to scavenge the crankcase when not under boost plus a boost-check valve that will allow the crankcase to drawn in fresh air. The MM system works as a PCV closed system when not in high boost, and as a vented 'relief valved' vent when needed. Really is the best of both.
 

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releases excess crankcase pressure; there is no "ventilation" or recirculation of crankcase vapors in that scenario. Yes, it's saving the rear main seal but at the expense of unnecessary pollution

The 1920's called - they want their fancy "draught tube" back. :ROFLMAO: Although, the 1920's draught tube was actually more effective than your open breather setup as it had a second vent as a means to pull fresh air into the engine.
And don't forget the STANK.
Reggie's is mounted exactly the way Improved Racing and someone else had told me... by the air cleaner to suck the stank into the engine... which works pretty much only at speed but idling in the drive-thru? not so much.
 

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Make sure and confirm the MM PCV works post install. I had a MM wild gen iv can setup (2017ish) and it did not work as advertised. I was instructed to drill out the PCV to a larger size and etc etc.

Then switch from oil fill to valve covers, and back to oil fill.

My blower was a mess with oil when I yanked it, and overall it was pretty disappointing. A shop that installs hundreds of these did the work and said that’s a first they have seen regarding the PCV issue and “update” stated to fix it the PCV issue.

Power on that combo was in 8xxwhp and maybe explains why they went to a new gen v setup? 4 digit power seems to be the norm these days in the high hp world.


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That's actually why I'm asking - I only saw lines to two valve covers; but then it clicked! The DMS can is simply open-venting to atmosphere.. Running an "open" filter, venting to atmosphere, is almost useless in our cars and isn't recommended, as it only releases excess crankcase pressure; there is no "ventilation" or recirculation of crankcase vapors in that scenario. Yes, it's saving the rear main seal but at the expense of unnecessary pollution and concentrating combustion byproducts (ie sulfurs, fuel, moisture and contaminants) within the crankcase, and ultimately your oil. This will dramatically shorten oil life, cause corrosion to internal parts and generally be bad for bearings over the long haul.

The 1920's called - they want their fancy "draught tube" back. :ROFLMAO: Although, the 1920's draught tube was actually more effective than your open breather setup as it had a second vent as a means to pull fresh air into the engine.
Evacuation of the crankcase, as well as circulating clean fresh air through the crankcase, is very important.

If the above is not accomplished, then sludge will form in the crankcase. Also, having a crankcase filled with an oily film, as well as being under high pressure, will see the oily film easily be drawn up into the cylinder during the intake cycle. This can easily lead to highly destructive, self detonation.

Your road 'Draught Tube,' I believe is also called a 'Road Draft Tube'.

Road draft tubes were popular until around the early 1960's, when we first began to see PCV Systems.

Inside the intake manifold, down in the engine valley, we would see these:
Does this remind you of something which might be on your engine today..lol
Green Motor vehicle Vehicle Gas Auto part


To which the road draft tube was connected to, on the outside of the engine:
Composite material Bicycle part Auto part Tool Nickel
 
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At the moment I have both valve covers running -10 to a vented Peterson can with my valley port blocked.

The bung post Tb is my vac source for my brake booster.

I can’t confirm if it’s working well or not as I’ve only done 500km in it.
 

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personally im not a fan of using vacuum on the breathers, ill be having my crank to catch then to intake before TB but after filter, then each rocker cover to another catch and then to the intake like the crank is, this way u still get the exact same use as WOT just u dont get the vacuum under deceleration/idle sucking all the oil thru, so far i havnt had a catch that with vacuum on it would catch all the oil some always still gets thru,

or what u could do is just vent one side of the rockers thru a 3rd catch so it then also sucks in fresh air if needed with intake airflow on the crank and other rocker cover but this way may cause smells in engine bay, keeping them all to intake stops the smells and as its not vacuum dosnt draw oil thru but u will get condensation in the catch building up that will need emptying every few days
 

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personally im not a fan of using vacuum on the breathers, ill be having my crank to catch then to intake before TB but after filter, then each rocker cover to another catch and then to the intake like the crank is, this way u still get the exact same use as WOT just u dont get the vacuum under deceleration/idle sucking all the oil thru, so far i havnt had a catch that with vacuum on it would catch all the oil some always still gets thru,

or what u could do is just vent one side of the rockers thru a 3rd catch so it then also sucks in fresh air if needed with intake airflow on the crank and other rocker cover but this way may cause smells in engine bay, keeping them all to intake stops the smells and as its not vacuum dosnt draw oil thru but u will get condensation in the catch building up that will need emptying every few days
Are you using vented or closed cans?
If they are closed, I would think that the small connection back to the intake tube would be pretty restrictive at WOT, leading to the system building pressure?
 

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Are you using vented or closed cans?
If they are closed, I would think that the small connection back to the intake tube would be pretty restrictive at WOT, leading to the system building pressure?
will be closed, then there is suction on the vents from the intake at all times and more so at wot then if there is any bulld up of pressure in the engine the vents are the easiest path out for the air, ill be using min -10 hose maby -12 to keep airspeed low from the rocker covers, the crank as its small from the valley outlet ill prob go up to a -8 thru the catch to intake, just think of it doing the same work as venting just u have the intake there to assist it making it a lower pressure in the intake and high always goes to low pressure
 

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Regarding windage.

An engine being built to make 1000 flywheel horsepower,
will require ~1500 CFM of air to do so.

If you’re moving 1500 CFM on top of the Pistons, you’re also
moving 1500 CFM on the bottom of the Pistons.
 
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will be closed, then there is suction on the vents from the intake at all times and more so at wot then if there is any bulld up of pressure in the engine the vents are the easiest path out for the air, ill be using min -10 hose maby -12 to keep airspeed low from the rocker covers, the crank as its small from the valley outlet ill prob go up to a -8 thru the catch to intake, just think of it doing the same work as venting just u have the intake there to assist it making it a lower pressure in the intake and high always goes to low pressure
The -10 hoses seem great, but how small is the connection that all that flow is being necked-down-to at the inlet tube? If there's a really big fitting there, should work fine I would think, to take care of WOT.
Still seems like a PCV valve would be desirable for actively evacuating the crankcase at other times.
 

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The -10 hoses seem great, but how small is the connection that all that flow is being necked-down-to at the inlet tube? If there's a really big fitting there, should work fine I would think, to take care of WOT.
Still seems like a PCV valve would be desirable for actively evacuating the crankcase at other times.
my rocker covers have a -10 fitting size so i may just go that or a -12 is pretty close ill check it out first see what suits (and looks good) and my catch cans have -10 inlets and -12 outlets will be using a big 2L i think it is, i may even use a filter on the outlet of the catch to see if any is going thru and make changes if so, my base is LS2 so my crank breather is only a internal baffle setup ours didnt get any PCV valve, but really the rocker covers will be doing most of the work and they feed into the crank/valley area anyway so should be plenty of breathing, my last setup was ok and it just used the two factory 5/16 rocker outlets and crank breather just venting i did get some oil out of the rocker covers until i opened up the second rocker cover then that fixed it
 

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-on windage-
Some have stated that windage is simply managing air flow through the crankcase of an engine.

I am beginning to believe that some of the issues we have been calling 'Blow-By', is related to 'high' crankcase pressures, caused by spinning these engines to an rpm, not ever considered by the GM Engineers.

Our engine blocks are called a 'Y' Block.

GM did this, as GM's engine blocks are made of aluminum (weak),
and a Y-Block is deep and strong in design.

However, as the engine skirt is deepened, the windage issues becomes greater. This because the area around the reciprocating mass, will now be increased. Your now going to hold more air, as well as more oil, and oily mist. All of this has a weight associated with it.

But that is only one of the major problems. The other is; the pistons are going to naturally be moving faster, as the engine rpm is increased. And there will now,most likely, be more air pressure being built up under those pistons.

Theoretically one piston moves up, and one piston moves down. And the resulting delta pressure, would then be assumed to be equal to zero. To help this, GM added the inter-bay passages. But, at what engine rpm will they no longer be effective?

-what we do know-
We do know that an engine block, built from high grade iron alloys, not of a 'Y-Block' design, does not have the same issues regarding windage, that even a well designed, bay-to-bay windowed Y-Block does.

Piston speed for an LSA 376 CID Engine, at 6800 engine rpm. . .
Mean Piston Speed: 4105 Feet Per Minute.
Peak Piston Speed: 6445 Feet Per Minute.

Total Piston Area: 103.8 Sq."

Here is an interesting read and video.
 
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-on windage-
Some have stated that windage is simply managing air flow through the crankcase of an engine.

I am beginning to believe that some of the issues we have been calling 'Blow-By', is related to 'high' crankcase pressures, caused by spinning these engines to an rpm, not ever considered by the GM Engineers.

Our engine blocks are called a 'Y' Block.

GM did this, as GM's engine blocks are made of aluminum (weak),
and a Y-Block is deep and strong in design.

However, as the engine skirt is deepened, the windage issues becomes greater. This because the area around the reciprocating mass, will now be increased. Your now going to hold more air, as well as more oil, and oily mist. All of this has a weight associated with it.

But that is only one of the major problems. The other is; the pistons are going to naturally be moving faster, as the engine rpm is increased. And there will now,most likely, be more air pressure being built up under those pistons.

Theoretically one piston moves up, and one piston moves down. And the resulting delta pressure, would then be assumed to be equal to zero. To help this, GM added the inter-bay passages. But, at what engine rpm will they no longer be effective?

-what we do know-
We do know that an engine block, built from high grade iron alloys, not of a 'Y-Block' design, does not have the same issues regarding windage, that even a well designed, bay-to-bay windowed Y-Block does.

Piston speed for an LSA 376 CID Engine, at 6800 engine rpm. . .
Mean Piston Speed: 4105 Feet Per Minute.
Peak Piston Speed: 6445 Feet Per Minute.

Total Piston Area: 103.8 Sq."

Here is an interesting read and video.
i guess windage is sorta like a ported sub woofer box and even tho the speaker is moving in and out at the same rate u would think it evens out but yet there is always pressure pumping out of the port, this will be happening within the bottom end in our v8 with each piston pushing it at an angle against the other pistons forcing air down into the wet sump, this is why i got a aftermarket windage tray and crank scraper to try help the issue as i wanted to increase the rpm of my engine.

this is where i dont like using the vacuum (unless u spend big money on a serious catch can) as a big rpm gets all the oil vapor everywhere inside the engine and then once ur off the throttle u have a massive vacuum just sucking on the vents drawing the oil thru, with the venting or venting to intake properly i have never seen a drop of oil go thru (only water buildup from cold starts)
 

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i guess windage is sorta like a ported sub woofer box and even tho the speaker is moving in and out at the same rate u would think it evens out but yet there is always pressure pumping out of the port, this will be happening within the bottom end in our v8 with each piston pushing it at an angle against the other pistons forcing air down into the wet sump, this is why i got a aftermarket windage tray and crank scraper to try help the issue as i wanted to increase the rpm of my engine.

this is where i dont like using the vacuum (unless u spend big money on a serious catch can) as a big rpm gets all the oil vapor everywhere inside the engine and then once ur off the throttle u have a massive vacuum just sucking on the vents drawing the oil thru, with the venting or venting to intake properly i have never seen a drop of oil go thru (only water buildup from cold starts)
are you sayinhg your crankcase is just vented to atmosphere? you really want a vacuum on your crankcase it makes the rings seal better and makes more power
 
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are you sayinhg your crankcase is just vented to atmosphere? you really want a vacuum on your crankcase it makes the rings seal better and makes more power
i have vented and was ok, but now ill be venting into intake to help the evacuation of air, when its to vacuum it dosnt do anything when ur wot anyway its the same as just going to the intake, vacuum is only there when ur off the throttle or at idle and lower loads which u then dont need the vacuum to help as its not creating as much pressure inside, the vacuum way is the opposite of what u really want as u dont need it for idle but would be best at wot but engines dont work that way so going to intake is the closest u get to vacuum for wot unless u get a external vacuum pump
 

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i have vented and was ok, but now ill be venting into intake to help the evacuation of air, when its to vacuum it dosnt do anything when ur wot anyway its the same as just going to the intake, vacuum is only there when ur off the throttle or at idle and lower loads which u then dont need the vacuum to help as its not creating as much pressure inside, the vacuum way is the opposite of what u really want as u dont need it for idle but would be best at wot but engines dont work that way so going to intake is the closest u get to vacuum for wot unless u get a external vacuum pump
This seems reasonable. If the air is going into the intake, are there any issues with MAF calculations?
 

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This seems reasonable. If the air is going into the intake, are there any issues with the MAF metering ECM calculations?
im not using maf on mine only SD, but if u do try after the maf so u dont get any vapor on the sensor over time and see what its like, my little cruze 1.6 turbo has the breather after the maf and its fine there, i tried it to manifold vacuum and fuel trims were 35% lean, then changed back to intake after the maf and even tho its not being sensed there was no change to fueling at all, it will be a different flow being the V8 tho so just see what its like if it has to go in front then it will have to go there, or if u run an airbox then that will be a point of vacuum on the intake side of the filter
 
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