Sealing up hose barb into air pipe - what product to use?

[lmoengnr]

What happens when you suddenly lift your foot off the throttle?

 

[RevNev]

Nice, but from all my research catch cans dont do much (if anything) at high acceleration - 'cause intake manifold has no vacuum, therefore can wont draw anything out of intake.
The way mine works it has dirty air in (middle) and 2 clean air out - from wherever higher vacuum is found (intake manifold at low throttle and post maf high throttle)

Now @RevNev if you can educate me I am all ears!

It's my understanding the can needs an alternate source of vacuum for oil separation at high throttle.

At higher RPM, the engine generates sump pressure and vents through the PCV system taking oil vapor with it back into the manifold. The catch can catches the oil and prevents it getting burned in combustion and causing detonation.

With the race engines, we vent them to atmosphere through the catch can.

Dry sump systems run at a vacuum and increases with RPM from pump suction at the scavenge ports in the sump, but wet sump engines will always generate pressure at high RPM.

 

[07GTS]

there is always suction on it and it still works at WOT because there is buildup of pressure in the crank case so the higher pressure always goes to low pressure so it should flow thru the catch to relive it straight away, when vacuum is applied it has to be thru a pcv valve so its regulated and not actual full vacuum u dont want it open to full manifold vacuum as that is just as bad on the seals as building up too much pressure, factory use a valve or a tube like on the LS if u look inside it will have a much smaller hole within to stop the full vacuum on the manifold connections

 

[RevNev]

there is always suction on it and it still works at WOT because there is buildup of pressure in the crank case so the higher pressure always goes to low pressure so it should flow thru the catch to relive it straight away, when vacuum is applied it has to be thru a pcv valve so its regulated and not actual full vacuum u dont want it open to full manifold vacuum as that is just as bad on the seals as building up too much pressure, factory use a valve or a tube like on the LS if u look inside it will have a much smaller hole within to stop the full vacuum on the manifold connections

It's much easier to understand the PCV concept with the traditional PCV valves on the old engines, where the later engines have a more concealed setup with greater difficulty to see how it works but essentially, it's the same functionality.

 

[dassaur]

At higher RPM, the engine generates sump pressure and vents through the PCV system taking oil vapor with it back into the manifold. The catch can catches the oil and prevents it getting burned in combustion and causing detonation.

With the race engines, we vent them to atmosphere through the catch can.

Dry sump systems run at a vacuum and increases with RPM from pump suction at the scavenge ports in the sump, but wet sump engines will always generate pressure at high RPM.

I thought at high RPM, depending on cam, there would be relatively little if no vacuum to pull the fresh air through?

there is always suction on it and it still works at WOT because there is buildup of pressure in the crank case so the higher pressure always goes to low pressure so it should flow thru the catch to relive it straight away, when vacuum is applied it has to be thru a pcv valve so its regulated and not actual full vacuum u dont want it open to full manifold vacuum as that is just as bad on the seals as building up too much pressure, factory use a valve or a tube like on the LS if u look inside it will have a much smaller hole within to stop the full vacuum on the manifold connections

Yep I get the PCV orifice system the LS have.

Has anyone read 'The CCV (Crankcase ventilation' Bible'?

https://www.shophemi.com/images/media/p-2591-p-2273-arrington_ccv_bible.pdf

 

[RevNev]

I thought at high RPM, depending on cam, there would be relatively little if no vacuum to pull the fresh air through?

At closed throttle, the bigger the cam or more valve overlap the less vacuum to the extent that big cammed car can run out of vacuum to operate the brake booster. But as 07GTS said, the vacuum applied to the PCV valve is regulated and minimal and will be sufficient enough to vent the engine at idle or closed throttle with fresh air pulled from the airbox tube attached to the rocker cover.

The issue is high RPM wide open throttle when the engine generates sump pressure but the pressure in the manifold or plenum where the PCV valve is attached, is always a lower pressure than generated from the sump to the rocker covers. However, that's when oil is blown into the plenum through the PCV system and burned in combustion. The catch can you've fitted acts as an oil separator, so the plenum receives only vapor.

Oil can also be blown into the airbox at high RPM, wide open throttle if the sump pressure is excessive or PCV system too restrictive at low vacuum.

The 5 litre EFI Holden engines were bad at throwing oil around and blowing smoke out of the exhaust when driven hard on a track day. We had to disconnect the PCV system and vent the rocker cover directly into a catch can like the race engine setups. The LS engines were much better!

 

[RevNev]

Has anyone read 'The CCV (Crankcase ventilation' Bible'?

It's not a bad article with some good insight however first and foremost, we must keep in mind that a PCV system is an "emission control device" and it's not for making horsepower and clean combustion. When we vent blowby gasses back into the intake manifold, were robbing the manifold of oxygen and reducing the manifold's effectiveness for the engine to burn fuel. Oxygen will burn more fuel and make more horsepower than blowby gasses. It's the reason race engines never use a PCV system.

But on a road car much like zero cell cats and venting blowby gasses to the atmosphere, you'll smell it in the car and generally turn a nice performance car into smelly pile of unpractical crap unless it's running on E85 and alternatively smells pretty good!

 

[dassaur]

It's not a bad article with some good insight however first and foremost, we must keep in mind that a PCV system is an "emission control device" and it's not for making horsepower and clean combustion. When we vent blowby gasses back into the intake manifold, were robbing the manifold of oxygen and reducing the manifold's effectiveness for the engine to burn fuel. Oxygen will burn more fuel and make more horsepower than blowby gasses. It's the reason race engines never use a PCV system.

But on a road car much like zero cell cats and venting blowby gasses to the atmosphere, you'll smell it in the car and generally turn a nice performance car into smelly pile of unpractical crap unless it's running on E85 and alternatively smells pretty good!

Thanks for the insight!
So in your racecar you are venting to outside rather than back into engine... I can see how that works at high throttle.

And I see how high throttle =low vacuum on normal pcv systems which can cause reverse flow.
I have put one way check valves on mine too, but probably don't need them with the 2 sources of vacuum

Thanks

 

[RevNev]

So in your racecar you are venting to outside rather than back into engine.

Yes, it's ideally the best way but I wouldn't do that with a nice VF unless it was a dedicated track car. Using catch cans as an oil separator as you've done is the best road car option.

I have put one way check valves on mine too, but probably don't need them with the 2 sources of vacuum

I'm not sure about the check valves as I can't see where the hoses are fitted.

 

[lmoengnr]

It's much easier to understand the PCV concept with the traditional PCV valves on the old engines, where the later engines have a more concealed setup with greater difficulty to see how it works but essentially, it's the same functionality.

Like grey engines, U turn out of the rocker cover and straight overboard down near the sump!