Hi guys,

What's the best way to setup an oil catch can setup for a 20V blacktop with open velocity stack?

Is it best to retain the PCV valve or not?

This is for a race car, so preventing knock and reducing crank drag (from pressurizing the crank) would be the priority.

If you are running the factory ECU, keep the PCV and use a non-vented
catchcan inserted between the PCV and the connection into the common
vacuum rail. So, PCV ==> catchcan ==> vacuum rail.

Cheers... jondee86

I'll be running a Haltech.

Is there a better way to run it?

The standard blacktop has an air-swept cam cover, where the PCV extracts enough
air to keep the cam cover under a slight negative pressure during normal driving. At
high rpm's, blowby may exceed the ability of the PCV to capture it all, and the excess
will vent out the tube connected to the back of the cam cover, and into the intake
airbox. At normal speed, some amount of filtered air will be drawn in from the airbox.

This is an environmentally friendly system that ensures all blowby fumes get burned.
As racing is by definition, not environmentally friendly, providing your catchcan meets
the regulations for the class you are running, pretty much anythng goes. Here is an
extreme example of a race setup...



This is a turbocharged engine using four vent hoses and four filter/vents. For a N.A.
application two decent sized hoses and two vents would be sufficient. The hoses are
large enough to keep the air velocity down, and ideally there should be a baffle fixed
inside the cover under the hose connection point to stop the cams throwing oil directly
into the opening. The fittings on the cam cover should slope back into the cover if
possible to allow some drainback of liquid oil.

The catchcan/s should be a decent size and have both internal baffles and some form
of "stainless steel wool" or equal packing, to provide a high surface area with low
resistance to airflow for inertial separation and coalescing of oil vapor/droplets. The
filter/vents should also be a decent size to keep the exit air velocity down.

Being a vented to atmosphere system, there is no chance of oil vapour messing with
your octane rating or AFR's. Your throttles and intake will stay clean. On the other
hand, you will sometimes smell hot oil... real race cars always smell of hot oil !! And
after a while a fine film of oil will start to cover your engine bay. Think of that as an
anti-corrosion treatment

Cheers... jondee86

Thanks Jondee ! for your detailed response.

After doing some more research, i'm thinking of leaving the stock PCV hose connected from front intake side of cam cover to the vacuum rail.
Then connect a vent to atmosphere catch can to the rear of the cam cover.

the catch can will be a radium can with the baffled internal and stainless filtration media
http://www.radiumauto.com/Universal-Sin ... -P178.aspx

Will this work ok?

or is it better to plug the port on the vacuum rail, then connect both ports (side and rear of the cam cover) to a vented catch can?

There are many tales about 16V engines blowing oil out the cam cover vent,
but this does not seem to be a problem with N.A. 20 valves. Boosting either
engine and revving the snot out of them will put all the oil on the outside of
the engine in short order

You could try leaving the stock PCV plumbing in place, and just add a small
filter to the vent at the back of the cam cover. Many people do this and seem
happy enough with the result. If you get oil dripping down from the filter after
a while, then try Plan B.

Plan B. Block the vent at the back of the cam cover, remove the PCV and fit
the largest diameter hosetail that you can get into the hole. Run a hose from
there to your vented catchcan. At least 1/2" hose and preferably 3/4" hose.
But, if you don't mind the extra plumbing and you get a catchcan with two
connections, use the rear vent as well and put 1/2" hose on each.

Cheers... jondee86

jondee86 wrote:If you are running the factory ECU, keep the PCV and use a non-vented
catchcan inserted between the PCV and the connection into the common
vacuum rail. So, PCV ==> catchcan ==> vacuum rail.

Cheers... jondee86

What about the port towards the back of the head?

Jeonsah wrote:What about the port towards the back of the head?

jondee86 wrote:You could try leaving the stock PCV plumbing in place, and just add a small
filter to the vent at the back of the cam cover. Many people do this and seem
happy enough with the result. If you get oil dripping down from the filter after
a while, then try Plan B.

The vent at the rear of the cam cover will have air flowing in more often than
fumes flowing out... if the PCV system is still hooked up. Otherwise, Plan B

Cheers... jondee86

that port on the head that people (like me) just put a filter on, could one actually plum that to the port that normally was for the power steering on the stock airbox? it has that extra barb that none us use

Good question Although I have had a couple of sets of ITB's and a 20V thru
my hands, I have never run one in my car. So I just took it for granted that the
cam cover vent hose hooked up to the factory airbox. But looking at this pic and
a couple of others, I see the vent actually hooks up to the intake air duct...



So it makes no difference where you hook up the vent tube... so long as it is
somewhere between the filter and the ITB inlets. The P/S tube looks a little
small, so maybe just install a hosetail in the airbox that matches the size of
the vent hose.

Cheers... jondee86

20V in longitudinal layout will have similar issues in left hand turns as the largeports do... there is no intake side drain on a 20V......

The intake side drain helps significantly when it comes to pushing oil out the vent tube, as the oil can't "stack up" because the drain @ the back of the head acts as intended.

I've recently opened a silvertop and did a little diagram...




I'm pretty sure the blacktop is the same, or very similar. So as in the 3S engine in Jondee's pic, I'd add a curved 1/2" breather tube to the intake side of the cam cover between the 2 vents

the current oil catch can doesn't seem to be working correctly.

this is a 20v blacktop with ITB
I left the stock PCV connected to the vacuum block, then the rear cam cover port is connected to a vented Radium catch can.

on the dyno, the catch can was blowing out fume vapor (although no oil in the catch can), and the dipstick was popping out (might just be the dipstick being too loose)
the compression and leakdown test were good, so I'm assuming it's not a piston ring issue.

How come these engines have so much crankcase pressure?

here's the video on the dyno
https://youtu.be/feLZdFBoGi0

I'm abit weary to take it to the track like this, so the plan is this

1. replace stock PCV valve and see if it's better
2. remove stock pcv, get a catchcan with two -10an ports, run 2 x -10AN lines from the back of cam cover and the stock pcv port(with pcv removed) to the new vented catch can
3. I wonder if there is room inside the cam cover to build a baffle by the 2 ports?

any ideas guys ?

One of the jobs of a vented catchcan is to apply a thin film of oil over everything in the
engine bay to prevent corrosion. Yours looks like it is doing it's job

But seriously folks... if there is no oil in the bottom of the can, then what is blowing thru
the filter must be a very fine mist. And from your vid there does not seem to be much of
a draft around the can. On the track there will be a decent draft when you are at WOT and
you can expect that fume to get whipped away rather than hang around the filter.

So I don't think that you will be spitting oil on the track. Maybe try it an see... then if you
really do have a problem you can try and fix it

Cheers... jondee86