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Author Topic: catch cans  (Read 4928 times)

westybob

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« Reply #15 on: May 21, 2012, 03:23:28 PM »
Quote from: frost.motorsport;599303
I run a -8 from the front/right of my RB26 sump up to my catch-can.  Works nicely, though I have a Tomei sump baffle which helps stop the oil sloshing up there anyway...

I spent a long time investigating this issue while building my engine and came to the conclusion that the sump vent is the way to go.  

Interested to hear about other peoples experiences on this!


I have a Tomei sump baffle as well. People with RB26s have reported that the Mines baffles in the cam covers help too (although I am hoping I have it sorted now).

BUC957

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« Reply #16 on: May 25, 2012, 05:55:40 AM »
I have traces of oil going into my pcv hose off my intake cam. pretty sure its going from cam to value. what should i do?

westybob

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« Reply #17 on: May 25, 2012, 06:21:50 AM »
"Traces"? When you have litres of oil coming out you have a problem! Seriously I don't think you need to do anything unless you are planning to track or drag the car in which case it is time to look at a catch can set up.

BUC957

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« Reply #18 on: May 25, 2012, 02:07:12 PM »
Sweet as thanks

jade501

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« Reply #19 on: June 02, 2012, 04:35:10 PM »
my mates have got catch cans but none of them drained them back in because of the **** oil thats caught but a catch can i dont now y but when they drain the oil doesnt look prety.. on my 26 i was just going to do hoses into a catch im intersted into y the sump needs a breather and how does in help i got big wigde sump would a breater make a difference ???

BUC957

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« Reply #20 on: August 08, 2012, 10:07:00 AM »
hey guys i have a blocked factory pcv and catch can in another car. am looking for a two port with breather port. anyone know where to get one cheap?
« Last Edit: August 08, 2012, 01:17:00 PM by BUC957 »

xxfr

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« Reply #21 on: August 08, 2012, 11:20:17 AM »
Quote from: jade501;600096
my mates have got catch cans but none of them drained them back in because of the **** oil thats caught but a catch can i dont now y but when they drain the oil doesnt look prety.. on my 26 i was just going to do hoses into a catch im intersted into y the sump needs a breather and how does in help i got big wigde sump would a breater make a difference ???


The oil collected in a catch can becomes ****, as you have put it, when it gets collected in the can and absorbs moisture. The **** oil is basically oil and water that has mixed.

In a normal situation once the oil gets to the can, the fumes are vented, the oil is as good as what you have in your engine and is a good idea to have it returned to the sump as others here have noted.

As an example, Nismo only made a oil/air separator and returned the oil to the sump via the turbo return line.
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gtsr

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« Reply #22 on: August 09, 2012, 08:41:36 PM »
Quote from: westybob
The 30 crank whips up a storm and there is a fair amount comes out of those breathers (and its not blowby as I have done a leak-down test and it was fine).

I would think it's blowby. Rings should seal the bore at TDC when doing a leak down test.

Quote from: xxfr;603459
In a normal situation once the oil gets to the can, the fumes are vented, the oil is as good as what you have in your engine and is a good idea to have it returned to the sump as others here have noted.

Not a good idea if car is in a cold climate. The oil + water / condensation becomes ice and that blocks the return hose, so oil builds up and catchcan fills up.

xxfr

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« Reply #23 on: August 09, 2012, 08:56:19 PM »
By returning oil straight to sump you won't have any sitting in the can itself so no issues with blockages. The catch can performs the function as an oil/air separator, not an oil collector.
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gtsr

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« Reply #24 on: August 09, 2012, 09:26:47 PM »
What I'm trying to say is the hose that sends oil to the sump from catchcan gets oil sludge buildup over time and that oil sludge buildup attracts water / condensation, which in cold climates turns to ice that blocks that hose. Then oil builds up on top of the ice and fills catchcan.

It's a well known problem and it's suggested to clean out that hose which sends oil to sump every once and a while (rod it out or replace) to prevent this oil sludge buildup from happening.
« Last Edit: August 09, 2012, 10:04:11 PM by gtsr »

BADHAB|T

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« Reply #25 on: August 09, 2012, 09:30:51 PM »
At what temperatures does that happen? Anywhere in NZ? I would have though engine bay temps would soon melt any water that freezes in a hose that runs right next to an engine.... unless the car is in Alaska or something ....?

gtsr

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« Reply #26 on: August 09, 2012, 09:48:10 PM »
Not sure on temps. Maybe in South Island where it snows?? It happens in snowy or very cold conditions where oiltemps don't get high enough (sludge buildup).
« Last Edit: August 09, 2012, 09:54:44 PM by gtsr »

xxfr

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« Reply #27 on: August 09, 2012, 10:44:11 PM »
Good point gtsr. Sorry I don't have information or experience on that.

On that thought though, I would say the grade of oil being used would come in handy.
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AGRORB

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« Reply #28 on: August 09, 2012, 11:13:48 PM »
If you dont need a catch can, dont fit one. Why fix what isnt broke.

I had one on my old R32 and it was just hassles, the smell of the fumes was nasty too.

If your taking your car to the track a lot, or you have motor mods that make using the factory PCV system impractical, THEN fit one, if not, its just a wanky shiny thing you dont need and wont make your car go, stop or handle better. Far better things to spend money on.
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gtsr

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« Reply #29 on: August 10, 2012, 02:23:54 AM »
Exactly, the factory PCV setup is actually a simple, good design and works in cold climates (direct into intake, no drains from catchcan that could clog) and is a no maintenance (don't have to empty catchcan), emissions friendly / no smell setup (blowby gas is vented into engine where it's burnt off).

Only major problems with factory setup on street or racetrack is the small amount of oil (measured at about a ounce every 10,000kms on the street with turbo charged engine) that gets into intercooler (dropping ability to cool air), and engine (dropping octane of gas which could make engine knock, clogging valves on engine, gets into idle valves, etc). That's where a catchcan comes in handy (to intercept this oil).

The left over blowby gas is then vented into engine where it's burnt off (emissions). But that causes another problem, where the blowby gas spoils the burn inside cylinders. You lose hp due to dirty burn inside cylinders (less oxygen) and with cleaner burn you get more oxygen instead of dirty blowby gas into cylinders hence you get a leaner A/F ratio (more oxygen) which = gain in hp. That's why when you vent catchcan, you have to retune engine, due to engine is running leaner and if have other mods making it run leaner.

Venting catchcan to atmosphere is similar to fitting extractors that extracts the dirty gas from cylinders on exhaust stroke thus gives a cleaner burn inside cylinders when sparkplug is fired (fuel, etc is injected and air enters cylinders before compression stroke, then compression stroke, then fires spark plug). So catchcan needs to be vented on a racecar to atmosphere to get cleaner burn inside cylinders. On road you can't due to emissions, so has to go back into intake.

Quote from: xxfr;603564
Good point gtsr. Sorry I don't have information or experience on that.

Thank you for your kind words. It's ok, we are all learning new things everyday. Think of it as a new thing you have learnt about that setup (how to service that setup, known problems in cold climate). :)

Quote from: xxfr;603564
On that thought though, I would say the grade of oil being used would come in handy.

I agree, that probably would play a role as well. :)
« Last Edit: August 10, 2012, 08:16:16 PM by gtsr »