I currently have a block and separate cam cover breather setup going to an open-to atmosphere catch tank. But at high rpms the engine has a tendency to push a bit of oil out (compressions etc all good, and only happens at 6000+)

I am hoping to put a sealed catch tank in place of the open one, with an added connection to manifold vacuum via a PCV as used by all OEM cars. Now the downside. I have bike ITBs, so how to I connect a PCV to them? drill the inlet, pop connectors in each runner (10mm?) and make a balance pipe, which then connects to the catch tank?

Another idea....I an going to convert fro what looks like a huge K+N oval filter to an airbox. I could pop the connection into the airbox, or even the tube section where the hose/cone filter will connect. That may help at high RPMs with the old Bernoulli effect with high velocity air rushing over the hose end.

Or is there a better way?

Personally I would rather empty a catch can on the odd occasion than mess about trying to pipe all that in!

Not sure on all types of PCV but on my old Evo it relied on the vacuum draw to pull it open to breath,so that type wouldn't work just piped into a air box.

I wouldn't use a pcv into the airbox. Just an open pipe.

The PCV is a simple yet clever bit of kit. But fitting to ITB's may be just too troublesome in practice.

What engine is it? On my Zetec the breather goes straight from the standard breather on the block to the air filter backplate with a T to the cam cover breather, This is similar to how most OEM setups work, at least on older carbed engines.

Vacuum pump either engine driven or electric perhaps?

ST170.

No, no space for any extra vacuum pumps, besides, there is a 2litre one installed already

Yep, the old skool type plumbing into the induction before the throttle bodies is probably the way to go. At high RPM the vacuum will be the same either side of the butterfly anyway, now I have though about it. And it is only at high RPM there was an issue. I guess if I lift, the c=vacuum will drop to nothing, but should make very little difference in real terms.

But ideas are still welcome...

Remove the PCV, removal is recommended for high performance engines, then connect crank breather into oil catch tank.

On mine you cut open the PCV remove the ball bearing and spring, glue back together and connect to tank

[Edited on 13/11/18 by big-vee-twin]