Catch can efficiency?

[knore]

Ive had a Greddy oil catch can on for some time now (with stainless scourers in a stocking as filter) and its worked pretty well. When i run higher boost it catches a bit of oil, most being about 10-15ml from some runs at willowbank. On standard boost its totally clean.

But i noticed i still get a bit of oil in the intercooler piping, it pools where the rubber joiners are.

Photos of my catch can setup are in the gallery, its the typical recirculating setup.

Except i know there isnt any oil getting past the catch can because the pipe going in is oil stained, and the pipe going out is completely clean.

I recently had a good look at my turbo and it seems to be in great condition, so why am i still getting oil in the intake and intercooler piping?

Im using Motul 300v Chrono which is 10w40, and the most boost ive run is 0.9bar

[Busky2k]

Perhaps your turbo seals are starting to let go? Pull off the AFM piping and inspect your compressor for any oil stains. Also check the compressor cover outlet aswell.

I dont run my catch tank recirculating. I mean what for? Better to keep the unmetered and potentially oxygen deficient air (being blowby gas mostly) out of the engine all together...

I couldnt tell how exactly how your catch tank is plumbed (I have an SR20 so I cant even guess!). Where is the outlet from the tank plugged into? Before the intercooler? My suggestion not running it recirculated, cleaning the pipes and then inspecting it again in 3 months time.

[Sydneykid]

I would run the catch can venting to atmosphere for a while and see if that fixes the problem.

[Targa Tom]

Sounds like a terrorist, eh? It's OK, I lived in Brisso for 10 years eh, and sometimes remember how we used to talk eh?

Anyhow, we ran a fair bit of boost(more than std anyhow) at Basky on the weekend and the catch can copped a hiding... But inlet piping is clean. When we run the return in Targa the oil in the intake pipes occurs. But at circuit we vent both the oil and BOV to ambient.

Take Skyds suggestion, reckon you'll find he is onto it...

TT

[REDFC]

I would run the catch can venting to atmosphere for a while and see if that fixes the problem.

Hey, how do you vent them ? Do you dril a hole on the lid you think ? what size hole is sufficient ? Also which tank would you recomend.

OR

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Cheers... sorry if i went offtopic just doing some shopping

[knore]

I would run the catch can venting to atmosphere for a while and see if that fixes the problem.

Ok thanks for that sk

Im still a little unsure as how it vents to atmosphere if you have no pressure/suction involved?

IE when you have it recirculating like my current setup, there is sucking from the turbo drawing the blow by into the catch can.

If you remove the hose going to turbo and replace with a little vent to atmosphere filter, Whats sucking the blowby air out through the filter?

Under revs does the blowby actually get pushed out aswell as sucked by the turbo?

[Busky2k]

Nothing gets 'sucked' out. The pressure in the crankcase (thanks to blow by) will force any of the gases out on its own... Try taking off your oil cap while idling, and you'll see what i mean.

[Cubes]

How does this affect the idling and smoothness of idle?

When I pull my dip stick or oil cap off the car wants to stall, then it begins to idle hunt as it tries to raise the rev's to stop it stalling.

The Rb20DET was much worse and would stall most of the time. The RB30DET will keep running but the idle isn't the best.

[Busky2k]

Ah, well thats cos of the PCV valve (positive crankcase ventilation) system Joel. On a stock car, some engine vacuum is passed into the crankcase via the PCV at idle and light loads. The vacuum draws in the blow by gasses to get burnt. (At full boost, the valve shuts so no boost goes into the crankcase.) You dont get idle problems because the other side of the crankcase is connected via a hose to the turbo cold pipe after the AFM. So any excess air that is being sucked in thru the PCV is being metered and thus is a closed system. By creating a 'leak' in this system via opening the oil cap or dipstick, unmetered air goes into the crankcase and through the PCV, and thus that would explain the idle roughness. That is why when you vent the crankcase to atmosphere (instead of letting it get blown into the turbo cold pipe), you should plug up the PCV or you will get idle problems..

[someonestolecc]

Just out of interest I read this post and my intercooler piping has this thin film of black dust looking stuff. This extends all the way into where the inlet pipe goes into the turbo. Would that be oil?

I have a catch can and it currently vents to atmosphere although I've never seen any oil come out of it. I will be plumming it back into the inlet pipe somewhere for engineering (as the crank case can't vent to atmosphere) so I think that's why people do that Busky.

[Busky2k]

If you wipe your finger on the inside of the pipe and you got residue, thats oil for sure. And yeah venting to atmosphere is a big no no in terms of emissions, but bah, who wants their intercooler and inlet manifold filling up with gunk eh? PCV and EGR dirty up inlet manifolds like you wouldnt believe. Its gross! =(

[FATGTS-R]

Yeah, I suffer a lot with my inlet system being coated in oil as well.

My friends car is currently in a workshop getting a shite load of work done and they have plumbed his blow by system straight into the exhaust, before the cats?

He tried to explain it to me but I dont think he fully understands it himself. They welded a little tube on an angle facing the exhaust flow and there is some type of valve on there that opens and a vacuum is created sucking the gas out.

Somethin like that anyway. The workshop reckons its legal as the heat from the exhaust burns it up or some crap like that anyway.

I doubt it is legal but I guess its a lot better than an intake system full of oil and would be a lot easier to conceal from the defect army.

[discopotato03]

I think thats what the Americans (and David Vizard) call an evacupan system . It works on the principle of fast moving exhaust gasses past the vent tube creating a depression or area of low pressure to draw out crank case gasses . The valve used is a check or one way (outwards) valve also known as an anti backfire valve . It prevents crank case explosions should the engine backfire and ignite the crank case gasses . There is a small write up about doing this in David Visards book , How To Modify Ford S.O.H.C Engines .

Gotta get the primates to school more soon .

Cheers A .

[someonestolecc]

If you wipe your finger on the inside of the pipe and you got residue, thats oil for sure.

What if it's almost a powder?

Bugger. One thing after another with this car.

[Busky2k]

Nah I noticed a very slight grey powdery substance coating the piping after the intercooler. This was when I bought the car stock which had always run the stock airbox and paper filter. I think its just very minute amounts of dust settling in the pipes, over the last 7 or so years the car had been run for. I wouldnt worry at all!

[someonestolecc]

Ahh good stuff.. Yeah cos it's all over the pipes but it is dry. There's no liquid in there at all.

It also smells funny

"It tastes like grandma."

Thanks for the reply - welcome as always Bus.