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Old 04-24-2010, 03:40 PM
courtney c courtney c is offline
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Default what is the purpose of a crankcase vent line that is attached to the...

...airintake on a 2009 GMC sierra 1500 ?
and also why isnt there one on a cold air intake kit from K&N
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Old 04-24-2010, 08:00 PM
Molson02536 Molson02536 is offline
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Originally Posted by courtney c View Post
...airintake on a 2009 GMC sierra 1500 ?
and also why isnt there one on a cold air intake kit from K&N
PCV systems are just that, positive ventilation, they should have called it negative ventilation valve. They try to put a negative pressure in the case. Not positive. Guess folks would of been even more turned off by NCV though and the word negative. And yeah, yeah, I get the meaning of positive for the valve, meaning its not a static system, its active.

The blow by gases are low in oxygen, high in oxides, carbon and nitrogen oxides. So you think, oxides, that's an oxygen rich element right. Well yeah, but the oxygen is bound to the carbon and nitrogen. Not easily used as a combustion contributing gas. So yer stuffing this fairly inert gas back into the intake, where you want oxygen. I'm not a fan of stuffing the intake with inert gases.

So.. What's a good system. Well the idea would be a vacuum for the case that isn't fed back into the intake. So that means a pump for the sole purpose of evacuating the case. Kinda costly, money and performance.

A venturi type units that work off of the exhaust are nice. But fluid control (oil vapors and raw oil) becomes an issue. Proper baffling can take care of that in a big way. Still looking at that type of system with proper oil control. I honestly think its a really good system, as long as you can separate the oil vapors before it hits the exhaust.

Each valve cover is ported on your engine, one to the intake tube and the other in to the manifold for engine vacuum. Yup, your recycling the poor gases back into the intake. Its a simple means to get a decent amount of vacuum to help clean the case out. With the K&N intake, your going to have to add a atmosphere vent off the breather line or from the valve cover, but the trade off from getting a little more "positive" pull of the vapors VS the issue of introducing useless gases in the intake is a trade off that your going to have to decide. The K&N intake tube will have to be modified to accept the PVC tube to recycle the crank case gasses if you like.

I my self still thinking of using the vacuum available from the gas flow of the exhaust. Free use of energy there. I just want to make up a nice oil separation unit first to keep the oil out of the exhaust system. I have some ideas!! Just a matter of playing with the separators I have made. Its coming soon. But yeah, PCVs are a nice idea, there are better, time will tell
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