cordycord

iTrader: (2)

Thanks John. This engine was "Night of the Living Dead" before the Scotch Brite was added, so no harm no foul. I ended up using stainless scrubber material on a different valve cover.

Since this episode I've spoken at the track with a couple of guys who have lots of experience with this issue. More than the scrubber material, the larger hole helps.

The biggest thing you can do is make sure that the stock baffles are sealed so that they work properly. I also re-installed my PCV valve and run either a catch can out the vent or a mini K&N breather. My newly-built engine with these changes has NONE of the issues and none of the blow-by of the old engine...mainly because it's not a tired old engine with crap rings.

MSMjohn

I have excessive blowby & crankcase pressure on my built Mazdaspeed 1.8L engine. The engine builder used Supertech pistons & rings when I asked for Weisco. I think its the weak piston ring spring tension (half of OEM rings) causing blowby.

Rather than taking my valve cover off & messing with the Mazda engineered system in it. I bought a aluminum oil cap & a 3/8 NPT fitting. I plan on drilling a hole in the oil cap, tapping & installing the 3/8 NPT fitting into it. Then I can run a parallel line into the stock catch can. This should get rid of excess pressures. I may run a second catch can in line on the stock catch can vent hose that goes to the intake. This way the air being vacuumed out of the engine through the catch can system will go through 2 catch cans. Under boost the PCV valve closes & there is no longer manifold vacuum pulling blowby out of the engine. There is a vacuum in the intake under boost that vacuums the engine through the catch can system & helps stop pressure from building up.

aidandj

iTrader: (5)

I would not be totally surprised if you didn't end up with giant oil puddles from your valve cover. @turbofan didn't seal his baffles well enough before a track day. And ended up pissing oil everywhere.

MSMjohn

The oil I'm getting is coming up from the oil pan. Pressure is pushing down on the oil & forcing it up the catch can drain tube. I tested the pressure & it was 1.7psi. I installed a Flyin Miata check valve & it stopped the oil from coming up but the engine still has that extra pressure building up. I want to get rid of that extra pressure. I tested my valve cover vent by having it vent into a clear gallon container & it did not spit out much oil spray. So the valve cover is working fine. My oil cap idea is much better than modifying the valve cover engineering. With the oil cap idea I have more options. I can change the NPT fitting to different sizes to change pressure. I can add check valves. I can add a oil catch between the oil cap & catch can.

Ted75zcar

iTrader: (2)

Oil catch bucket...

Joker

iTrader: (1)

Is the general consul for this still to use a copper based scrubber material like Chore Boy?

Look like its been a few years. Are the steps below still considered best practice?

1. Removing PCV
2. Reaming the chamber hole to ~ 1/4"
3. Copper based scrubbers in baffle chambers
4. Sealing baffle plates with RTV
5. Enlarging or welding intake and exhaust side vents to ~8an.
6. Running both lines to a vented catch can

psyber_0ptix

iTrader: (4)

I just ended up putting - 10AN's on both sides, enlarging holes and running to a two port catch can that is vta. Tried pcv with check valve, tried slash cut with little luck.

cordycord

iTrader: (2)

Try checking your compression. If you've got a tired engine, nothing will help. Ask me how I know...

psyber_0ptix

iTrader: (4)

Last year all cylinders showed 3-4% leakdown but I'll be checking again in the coming weeks.

I think for me it was a matter of the check valve not working well, or requiring more vacuum than was being produced, placement of the venturi and overall real estate for plumbing.

But regarding the list above, I never ended up putting foreign objects in baffle chambers. If I get a bit if vapor in my catch can, I empty it.

I honestly only really notice it most when running e85. You can smell the ethanol in the oil vapor condensate or when draining oil. It's been a year since E so I'm curious how this engine has been holding up.

Eunos91

6. Run both lines to a catch can, then run an additional line from the CC to the intake pre-turbo

Always a bit of vacuum will help with scavenging

cordycord

iTrader: (2)

The check valve for the 323 turbo is aluminum-bodied and is more robust than the OE Miata unit.

sixshooter

iTrader: (12)

I used 1/2 inch NPT fittings to 5/8 heater hoses to dual inlet and vented Allstar catch can.
I'm not a fan of the engine ingesting these vapors on a highly boosted car. Some of these vapors are combustible and can lower the effective octane of the combustion chamber mixture thereby promoting detonation. Oil vapors, for instance, have a much lower detonation resistance.

Tran

Thread revival... I've drilled the drivers side baffle hole out and welded a 10AN fitting to the roof of the chamber.

Now that everyone must have some miles on these setups, excluding a slashcut, is it still considered best to use scrubbers with a conventional catch can? Or perhaps no scrubbers and a radium air/oil separator plumbed into the sump?

sixshooter

iTrader: (12)

I'm using scrubbers and a catch can. See other thread.

1RMDave

Thread revival, sorry. How are those half baffles working out for you now? My car feels strong and is all good off boost but I set my ring gaps loose and have a lot of blow by, I'm pushing at least as much oil into my catch can as you were. I have both ports going to VTA catch can but I'm thinking about cutting the baffles tomorrow.

sixshooter

iTrader: (12)

Opening up the interior holes will slow the speed of gasses and let the oil not be pushed out as much. Scrubbers helped too.

1RMDave

That was my original plan TBH. I ordered a pack of the chore boy copper scrubbers to use in the can and VC, then I stumbled upon the half cut baffles and got curious. I am also considering adding a fitting to the dipstick tube and adding a vent there so that the blow by doesn't need to flow through the head as much.

EDIT: now that I think about it, the dipstick tube is a bad idea and is likely to push oil through there if used as a vent. Anyone ever consider adding a port the front of the pan, opposite the oil return? Maybe run it to separate catch can? Similar idea to the pcv canister honda used to run on the back of their blocks.