Unmetered air through oil filler?

Wow that is an old picture....

SMOKEDYA said:

And one more thing...if doing like groverdill did?Do i need to run that hose into the air intake from both VC or just the one?I'm really confussed cause i see 99% of guys run the catch can with a turbo or S/C set up.peace
john

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John,
The only reason to run the hose in groverdills pic is for emissions concerns.

IMHO, eliminate the possibility of introducing oil into the intake tract... and just run breathers/catch can.

jason

Daggar said:

It's expected that crank case scavenging under power is accomplished by the combustion chamber gasses that vent past the piston rings. At idle, it's expected that there will not be enough of those gasses to make that scavenging happen. This is why there's a PCV system... It ensures that crank case scavenging takes place regardless of throttle setting. The better your rings, the more work the PCV will have to do.

Click to expand...

I was almost dead set on welding a -12 bung on each valve cover and draining them to a vented catch can/breather and plugging the PCV hole in the lower intake, but after reading through all of this thread, I'm not sure if I should leave the PCV system alone and use a check valve and separator between the upper and lower intake manifolds. This is for a twin turbo build with blow-through MAF.

I think this is the most debated and misunderstood topic in the Mustang modification world. Pushing gasses here, pulling gasses there, scavenging this or that, venting or sucking metered and non-metered air. My head hurts.

Black cloud and daggar (and any others interested)
I previously owned an 89 gt a serious cam and extensive engine work. when reassebling the engine i used the valve covers that the previous owner had supplied. these vc's had a simple filter element (breather) in the pass vc. I then added a vortech supercharger. the idle was so erratic after the supercharger install, worse then before. I always attributed this to the wild cam but was perplexed as to why it got worse with the addition of the vortech. well after much troubleshooting i theorized that crankase vacuum at idle with the throttle closed (from the pcv) was sucking a considerable amount of air in through said breather, traveling through the crankcase, up the pcv, and into the intake manifold UNMETERED. this exhibited the same symptoms of a serious vacuum leak. simply removing the breather and placing my hand over the hole in the valve cover smoothed the idle slightly. I was able to tune some of this out with a CraneCams Interceptor but still wasn't right...

Why was it worse with supercharger? because of the restriction the s/c created at low rpms the air sucked through the breather was more aggressive.

just my 2cents