Why specifically are oil catch can(s) needed

[64Chevy]

I've tried doing my research. I think I understand the following:

- oil catch cans minimize crankcase aerosolized oil from getting put through the intake system,
- this is not related to oil usage issues with some of the Voodoo engines (or at least significant oil usage, which seems to be an oil control piston ring issue), and
- for most, a passenger catch can collects some oil, a driver catch can very little.

Since the combustion chamber will already have a film of oil on the walls, I assume the thinking from keeping oil from being introduced into the intake is:

- maybe prevention of eventual sludge formation in the intake manifold runners,
- maybe prevention of crud accumulation on the intake valves,
- maybe prolonging spark plug life, and/or
- maybe slightly more power because of more perfect combustion without the oil being present.

Most of the information I found seems to point to the oil collected as the reason for the catch can, without engine tear down or boroscope pictures showing engines with and without catch can use. (The "see, here's the oil" with the assumption that said oil is damaging.)

Can anyone point me to data driven (versus opinion driven) reasons why catch cans are important to either prolonging the life or performance of the Voodoo (or other engines). I don't have any issue installing at least the passenger side catch can, but I'm looking for the reasons why it is a good idea.

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[jmn444]

IMO the benefit is minimal otherwise OEMs would install them to prevent warranty issues.

That said, its 150 bucks and I'm adding one when I get the car too lol

 

[dmann]

take a look or search into the track forum. It's covered there.

 

[Demonic]

My understanding was that it was more for preventing fouling of the MAF and throttle body. My catch can collects enough that I do feel better about it not being sprayed into the MAF. Some manufacturers do have oil separator systems in the cars, like BMW. But the BMW ones I've had to repair or replace were a convoluted mess of plastic that would eventually crack and fail in some difficult to reach spot and result in vacuum leaks. I greatly prefer the simplicity of a small aluminum catch can I can just unscrew and dump.

 

[64Chevy]

So I just looked at my engine, and where the driver and passenger PCV lines run. Both enter the intake system after the MAF, so that isn't a thing. The driver side enters between the MAF and the throttle body (which makes sense at this would not see engine vacuum, which may explain why driver's side catch cans don't catch very much--which may also indicate little risk). The passenger side enters after the throttle body (so it does see engine vacuum) but the only things it can gum up are the intake manifold and intake valve (unless there is some sensor somewhere there).

 

[Demonic]

In that case I'm curious to see what others say.

 

[64Chevy]

In that case I'm curious to see what others say.

Yep, me too, that's why I'm asking. I did search through the track forum, and based on some posts there I could see at high G-loads and max RPMs you might actually have the PCV system take in enough oil to cause problems. I think looked at for "track insurance" purposes (especially if you are running slicks, and running at 9.5/10s, and using the rev limiter as a shift light) they make sense. Not as convinced in other situations.

 

[mavisky]

- maybe prevention of eventual sludge formation in the intake manifold runners,
- maybe prevention of crud accumulation on the intake valves,
- maybe slightly more power because of more perfect combustion without the oil being present.

You really called out the 3 main points here. In my GT500 we also ran them as we didn't want the oil being pulled through the intercooler reducing it's efficiency as well.

 

[64Chevy]

- maybe prevention of eventual sludge formation in the intake manifold runners,
- maybe prevention of crud accumulation on the intake valves,
- maybe slightly more power because of more perfect combustion without the oil being present.

You really called out the 3 main points here. In my GT500 we also ran them as we didn't want the oil being pulled through the intercooler reducing it's efficiency as well.

Da question is, given how good detergent gasolines are these days, how much sludge/crud do you really get?

 

[mavisky]

It's not a required part, but given how much fluid I've captured in mine already I think it's relatively cheap insurance in the long run. In my opinion that amount of fluid running back through the engine isn't beneficial in any way so why not eliminate the negatives, regardless of how small they may be on the GT350.

 

[JackImpact]

I was actually just shopping for a catch can.

So technically, you can install two?

 

[mavisky]

I was actually just shopping for a catch can.

So technically, you can install two?

Passenger side will catch oil for all drivers. Driver's side really only catches anything if you're on the track you have to be really pushing it for long periods of time to pull anything through it.

 

[JackImpact]

Passenger side will catch oil for all drivers. Driver's side really only catches anything if you're on the track you have to be really pushing it for long periods of time to pull anything through it.

Ok that is what I gathered. If I dont have one installed from the previous owner, have to check, I am gonna put one in just in case. The peace of mind is worth it to me since warranty is almost up haha.

 

[Dominator961]

 

[jmn444]

- maybe prevention of eventual sludge formation in the intake manifold runners,
- maybe prevention of crud accumulation on the intake valves,
- maybe slightly more power because of more perfect combustion without the oil being present.

You really called out the 3 main points here. In my GT500 we also ran them as we didn't want the oil being pulled through the intercooler reducing it's efficiency as well.

I think this is more important, I ran them on a prior whippled car for this reason.... not nearly as likely to cause an issue on a n/a car IMO

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