Catch can advice

CARRisma · Post by **CARRisma** » Thu Aug 21, 2014 6:04 pm

I have a custom made oil catch can. Inside it, I have used 3.25 meters of zinc plated metal chain purchased from B&Q for £1.85 per meter.

Post by **Doggo** » Thu Aug 21, 2014 8:08 pm

Catch as you can, I'm not staying here long,
I'll be coming back early, or never at all....

11891952 · Post by **11891952** » Fri Aug 22, 2014 9:00 pm

Hi Josh. Is the Audi petrol or diesel? And it's worth investigating the crankcase breather system before installing a catch can. If its a petrol (or newer diesel) it's likely to have a dual system. That being that when it's off boost it returns the air into the intake manifold after the throttle plate. When it's on boost it will be returned to the compressor inlet. This ensures the crankcase is always exposed to a depression (helps with efficiency and power

), and never pressurised by the turbocharger (which would be bad for many reasons

). So worth ensuring that the can goes in a hose common to both if there is one.

Joe.

Shiny · Post by **Shiny** » Fri Aug 22, 2014 10:11 pm

I used the Scotch type pad scouters in mine.

'92 Si VTEC · Post by **jjmartin349571** » Sat Aug 23, 2014 6:01 pm

11891952 wrote:Hi Josh. Is the Audi petrol or diesel? And it's worth investigating the crankcase breather system before installing a catch can. If its a petrol (or newer diesel) it's likely to have a dual system. That being that when it's off boost it returns the air into the intake manifold after the throttle plate. When it's on boost it will be returned to the compressor inlet. This ensures the crankcase is always exposed to a depression (helps with efficiency and power ), and never pressurised by the turbocharger (which would be bad for many reasons ). So worth ensuring that the can goes in a hose common to both if there is one.

Joe.

It's a petrol mate, 1.8 turbo APU engine. From what I've seen online it appears that the block is vented from 2 places, the PCV up top and a breather port down on the bottom end. Hoses from these 2 join at a t piece and then this has a hose running to the inlet manifold. I will check to see if it does also return air to the inlet tract before the turbo, but from what I've seen online it doesn't appear to

I was going to fit the catch can just before the manifold.

11891952 · Post by **11891952** » Mon Aug 25, 2014 11:44 pm

Hmmm it may not, but I'd be surprised. With only going into the manifold it would pressurise the crankcase when boosting (even with a check valve installed), usually causing oil leaks from the crank/cam/pump seals...

I'll see what I can find out about that engine family.

'92 Si VTEC · Post by **jjmartin349571** » Mon Aug 25, 2014 11:52 pm

11891952 wrote:Hmmm it may not, but I'd be surprised. With only going into the manifold it would pressurise the crankcase when boosting (even with a check valve installed), usually causing oil leaks from the crank/cam/pump seals...

I'll see what I can find out about that engine family.

I started tracking the PCV hard line back yesterday, to have a look to see if it also feeds to the inlet prior to the turbo. Was a bit pushed for time though and Audi's insistence of mounting engines the 'wrong' way means that I need to really have a dig about to see what's what. My girlfriend is off work the next 2 weeks so the Audi will be off the road, I'll try and pull it apart one evening weather permitting and see what's what. From other builds I've seen online though it does sound like the PCV system only vents to one point in the inlet manifold, although it may just be that other people are doing it wrong, it's not unkown and Audi owners are just glorified VW owners afterall