Oil Catch Cans - to your Elise in 30 minutes or less

[Vampyre]

I need one too!! This is very popular on LS1 motors...

[codymac]

Originally Posted by charliex

Hell i'd hate to see the long answer.

I type fast, especially when I'm snockered.

[Chris Mackey]

Originally Posted by codymac

Read the link.

And getting stupider...

[Transonic]

Originally Posted by John

Looks good Dave - another thing to add to my "to-do" list once I get my car back...

^ Ditto. I'm bookmarking this.

[ChrisH]

Dave,
Do the cans stay cool enough on hot days with the engine running hard to condense the oil vapors effectively? I am concerned that the position you mounted them is a pretty hot location given its proximity to the exhaust headers and being in the upper part of the engine bay. Also, the gases pulled from the engine (via the crankcase ventillation hose, at least for one can) are hot and will heat the cans as well. Is it worth mounting the cans in a cooler location and running longer hoses (for example, mounting near the left side vent)?

[Rob T]

Originally Posted by codymac

Short answer? All engines experience some degree of blowby which results in some nasty gases in the crankcase, forced induction causes an increase in these gases. In a typical setting, these are run through a PCV system (one-way to prevent higher intake pressures from going back into the crankcase) into the intake stream. Some oil is invariably carried through the system and gets on/in everything as it's typically routed back to the intake source just downstream of air filtration. In a car running an intercooler, the intercooler commonly collects this oil.

The idea of this device is to condense the oil out of the blowby gases before allowing those gases to be recirculated into the intake. In Dave's set-up, it's preventing that oil from being dumped into the supercharger.

Ever see a dirty PCV valve that's sludged up? That's basically what's getting dumped back into the intake - the stuff that becomes that gooey sludge. Ever note that oily film in an airbox when you change an air filter?

There are other ways to address the issue but a closed system like this is fairly safe and clean (environmentally speaking).

Excellent! Thanks Cody.

[fpitas]

I'll add to codymac's explanation: oil in the intake charge can cause knocking (detonation), especially when you're supercharging. Even if you have no intercooler to worry about getting oiled, a catch can is a good idea.

[Dave]

Originally Posted by ChrisH

Dave,
Do the cans stay cool enough on hot days with the engine running hard to condense the oil vapors effectively? I am concerned that the position you mounted them is a pretty hot location given its proximity to the exhaust headers and being in the upper part of the engine bay. Also, the gases pulled from the engine (via the crankcase ventillation hose, at least for one can) are hot and will heat the cans as well. Is it worth mounting the cans in a cooler location and running longer hoses (for example, mounting near the left side vent)?

Don't know the answer to that. Ohio weather has gone from 90s to 50s in all of 2 days. Best I can do check it after the next hard run with a laser temp gauge (or I could touch it and see if it takes my fingerprint off ) I do know that Frank and Kaz have had their Greddy tanks in that same spot for a while, and haven't heard any negatives. I also have ceramic coated headers.

[iana]

Dave,

Can you tell me how/where the catch can system finally vents to atmosphere? Cant see how from your pics.

Ian

[Dave]

Originally Posted by iana

Dave,

Can you tell me how/where the catch can system finally vents to atmosphere? Cant see how from your pics.

Ian

The cans don't vent, they simply intercept the blow and condense the vapor, removing the oil. This is drained off periodically at the petcocks. The remaining vapor goes on to the TB, just as it did before cans were installed. EDIT: I've since added breather elements for direct vent to atmosphere.

[Transonic]

3 questions for ya.

#1 I'm guessing after they fill up you drain them through the bottom (marked in yellow), how do you get to them? Do you have to pull the cans out to drain 'em?
#2 How can you tell when they're full? The Greddy cans have a little thing on the side that shows the level of oil inside the can.
#3 How long do you think it would take for them to fill up, weeks, months? I'm assuming a FI car would fill up faster.

[Buz]

I thought that you would want the breather line to enter on the side of the can and exit from the top. That way gravity would help the mesh keep the oil in the can instead of some being drawn out of the exit into the motor as it passes by the outlet into the bottom of the can. I also just realized that I have a turbo diesel with a lot of boost that might benefit from a catch can. Do you think it is worthwhile on a diesel or does it just run on oil anyway? It definitely has significant blow by since the area below the pcv valve is filthy with oil residue. Is oil mist bad for a turbo compressor? There is no intercooler to worry about. Sorry about the hijack Dave, nice setup as usual.

[Dave]

Originally Posted by Transonic

3 questions for ya.

#1 I'm guessing after they fill up you drain them through the bottom (marked in yellow), how do you get to them? Do you have to pull the cans out to drain 'em?
#2 How can you tell when they're full? The Greddy cans have a little thing on the side that shows the level of oil inside the can.
#3 How long do you think it would take for them to fill up, weeks, months? I'm assuming a FI car would fill up faster.

You don't have to pull to drain...pull back the small radiator hose (one with the bleeder) and stick your hand in and twist. It is a little awkward holding the drain cup too, so I'm adding some rubber hose to petcock to drain out the bottom. A FI car will have a significant increase in blow by. I've not heard of too many using cans for N/A - primary purpose is to keep oil off the turbines and out of the intercooler.

Of course, if you track, you'll fill the cans much faster being on cam. I don't know the frequency yet, but guessing with street driving, you could probably drain at your regular oil changes. There is no indicator when the can is full, one minor drawback.

Buz - sorry, no diesel experience. (and thanks for the comments)

[Westrock]

The most important picture....

[Buz]

That makes sense, I did not know there was a tube to the bottom of the can. They can be vented to the atmosphere with a filter if you block off the returns to the intake. It is not emissions legal on a recent street car to vent it to the atmosphere.

[codymac]

Originally Posted by Buz

That makes sense, I did not know there was a tube to the bottom of the can. They can be vented to the atmosphere with a filter if you block off the returns to the intake. It is not emissions legal on a recent street car to vent it to the atmosphere.

Thought some folks had issues with the 2ZZ VTA'd but can't recall why.

[sleepe]

Does the engine run smoother? Any hp gains?
How often do you need to empty the catch can assuming the car is a daily driver?

Originally Posted by Bane

Here's my short answer:

It reduces the nasty stuff that normally flows from your engine into your intake.

[MyElise]

Catch it or burn it:

[fpitas]

I got the redesigned dual catch can assembly yesterday, with the small inlet angled like Dave suggested. I'm planning to install it this weekend and take some pictures. I've attached the PDF.

[darkSol]

Mine should be here tomorrow. I'll post pictures after the install.