Oil Catch Can? Options

[Jetsetsurfshop]

This is Rev's VW Bug. Jake built the engine for them a year ago.

[GregAmy]

So they inserted a bracket/bar across the void and used some studs/nuts to snug it down? Requires some extra machining/drilling but still do-able. Could even drill-tap into the case for fittings (though it's really thin there, risking cracking.)

I have to wonder: SCCA (among others) requires a 1-quart-minimum catch can. Think I can convince them that if everything terminates into the case that it's a "greater than 1 quart" catch can?

Yeah. Yep, I think I can.

I love being a rules nerd.

[RolinkHaus]

Being that I have a late 1975 does it require a PCV valve or can I just connect the hose directly?

[RolinkHaus]

In order for the oil catch can (oil breather) to work effectively, assuming the vacuum is coming from the air intake?

The question is the placement of the can? Most setups show the can mounted on the firewall. Would it not work better to mount lower? Trying to understand how to measure the amount of vacuum. Has anyone done this?

[GregAmy]

The air filter provides no significant vacuum to the PCV system. It's there simply as a receptable for oil fumes, so that the fumes can get consumed by the engine.

The PCV valve is a check valve, to allow pressure out as needed but not allow anything back into the engine. It's not a bad thing to have, given that the other end of the hose goes to the non-filtered side of the air filter housing.

The purpose of a catch can in racing is to keep oil and fumes from being dumped onto the track. The reason a (typically) 1 quart size is required is so that it's large enough to not overfill during a race. It is expected that the competitor will review it between sessions and empty as needed.

You originally asked if a catch can is something useful, presumably for a street car. Generally, I suggest not. It's only real value is keeping the air filter from getting oily, which is not really a terrible thing given you'll be checking it occasionally anyway. And if you run an oiled filter like a K&N is really doesn't matter.

[RolinkHaus]

Thank you!!

[GregAmy]

Quick correction: I got to re-thinking and just looked at my 2L D-Jet. The hose from the PCV actually goes to the filtered side of the air filtered housing. So it'll get a tad bit of vacuum since it exists between engine demand and the minimal restriction of the air filter element.

However, the logic does not change: it's not a significant amount of vacuum and it's not intended to be*. IMO, the only reason to use a catch can in a street car is to avoid getting oil/fumes in the air filter and intake manifold, and I don't see how the juice is worth the squeeze.

I personally don't think it's a problem or concern for a street car.

GA

*This is a different concept than using a dry sump oiling system on a race car. In that case, the dry sump suction stages will actually create a strong vacuum within the crankcase itself, with the purpose of keeping down the windage/droplets friction and seating piston rings much better. But this is a level of vacuum and oil control that we'll never see on our street cars.

[RolinkHaus]

Mine has a K&N.

[brant]

A breather box should not be mounted low

Also the plumbing lines to the box should not have dips in the line which would cause oil to get oil in the low spots and essentially plug the line

You didn’t my need a breather box for your situation
Brant

[Charles Freeborn]

Here is mine. Mounts to the cross bar on engine side. Feeds from a fitting where the distributor used to be and fittings machined into the heads. Goes to the little catch box that has a piece of screen and a block of coarse foam (sort of like fuel cell foam), and then exits out the back and dumps unceremoniously on the ground. I suppose some marshall will tell me the can doesn't have enough capacity and make me route it into another can of some sort. I'll fall off that bridge when I get to it.

Judging by the receipts from when the car was built the catch box probably came from Summit or similar.

[ChrisFoley]

No need to drill holes thru the sides of the tower to attach a flat cover.

[GregAmy]

No need to drill holes thru the sides of the tower to attach a flat cover.

Did you just jam that in down at the bottom? Gotta be careful not to tighten too hard, lest it pull up the aluminum block...

Do you sell this?

I'll convert the race car to that, it'll make the line routing a lot easier.

[ChrisFoley]

No need to drill holes thru the sides of the tower to attach a flat cover.

Did you just jam that in down at the bottom? Gotta be careful not to tighten too hard, lest it pull up the aluminum block...

Do you sell this?

I'll convert the race car to that, it'll make the line routing a lot easier.

When the aluminum block is rotated into position, the stud is then screwed thru to make contact with the shelf below and lock the block against the overhangs front and rear.

Its part of my horizontal cooling system. I never considered selling it separately.
The large sleeve is designed to accommodate the filler tower.

[GregAmy]

When the aluminum block is rotated into position, the stud is then screwed thru to make contact with the shelf below and lock the block against the overhangs front and rear.

Ah hah! ok, I see that now. I'll chat with you about getting one, but the top plate can be blank for me to tap/fit as needed.

[stownsen914]

Here is mine.

Looks like an electric fan setup. Does it cool the engine adequately?

[Charles Freeborn]

Here is mine.

Looks like an electric fan setup. Does it cool the engine adequately?

Yes, electric fan and shroud by AJRS (Alen Johnsen). Seems to do the trick. I haven't logged much track time with it yes on account of other issues. I have the fan thermostatically controlled by the CHT gauge. Comes on at 250º.
Plan is to add some air intake scoops on sail panels and duct directly to the fan opening.

[Jetsetsurfshop]

No need to drill holes thru the sides of the tower to attach a flat cover.

How much??

[Charles Freeborn]

Chris' flat fan set up is a thing of beauty. The cable weber throttle linkage too... maybe santa will be nice to me, but probably not..