Twin Chamber Oil Seperator

[xlnt6]

I have for a while now been designing and making an oil seperator for my T in the garage and finally I have completed it. This one is different from the standard ebay type product, as mine is custom designed to suit the Nizpro kit that I have fitted. It sits in the well between the rocker cover and the plenum and is made completely from stainless steel and I've given it the once over with the polisher.

It's actually two completely seperate oil seperators, the rear chamber is about 3/4 of the volume and takes the oil fumes from the rear PCV in the head and passes it thru a baffle pipe (internal in the chamber), thru stainless steel wool (I used the course S.S dish scourer which cost about $1 for two pieces from Kmart), then out via an interal 90 degree bend thru a one way valve and into the plenum. The front chamber gets oil/air from the forward breather. This chamber is about 1/4 of the volume and uses the same internal material. It connects to a custom front pipe which routes it's way around the rocker cover and connects to the air intake just after the filter.

Both chambers have dipsticks to check for oil level, as can be seen in the pics. You can see the dipstick screw (allen key head) for each chamber on the top of the chambers. Also the front pipe and rear pipe are removable via the fittings, so the seperator can be easily removed for emptying (there are two drain sump screws in the bottom side of each chamber).

I made this system as two seperate chambers, as it allows the seperator to work correctly under both vacuum and positive pressure scenarios. A single catch can cannot do this. The ones on ebay are really only suitable for NA applications, not turbo.

1. Engine manifold under vacuum. During this time, air is drawn from the air filter thru the front chamber and into the front engine breather. Oily air leaves the rear breather (via PCV) and is drawn thru the oil seperator and into the plenum, which is under vacuum. Oil is captured in the rear chamber. Air is circulated thru the engine.

2. Engine manifold under boost. During this time two things can happen depending on the relative pressure in the plenum and the rocker cover/sump.

a. At boost you would think the one way valve would stop any air passing from the rear outlet to the plenum chamber. And that is the case for some of the time. At a constant boost level and due to elevated RPM (and hence trashing of oil), oily air is forced at low pressure out the front breather, thru the seperator and it is consumed via the inlet to the turbo back into the engine. ie the flow is reversed from scenario 1. above. That is why in the stock system you get some oil residue in the inlet piping to the turbo.

b. Under high boost when you change gear, the throttle slams shut when you get off the throttle. This causes the plenum to suddenly become a large vacuum and there is a high relative pressure in the rocker/sump which means there is a large quantity of oily air forced thru the rear chamber and into the plenum.

With the single oil catch can system you see on ebay, many guys connect both the front and rear breather to the can. Depending on how you hooked it up two things can happen.

1. If you hook up both inlet and outlet to the can and don't connect the plenum at all, you actually don't get any circulation of air thru the rocker. So who cares. Well oil gets contaminents from combustion which get "boiled off" and these need to be purged to maintain good oil properties. Sure the oil filter removes some, but water and low weight hydrocarbons need to be removed thru vapour circulation.

2. If you hook up as above with manifold vacuum (ie oil can between the rear outlet and the PCV valve), you do get circulation but under boost the positive rocker pressure oil/air vapour can't go anywhere (ie it normally goes back to the inlet on the filter to the turbo). So what ??? Well the positive crank case pressure is working against the underside of the pistons and is actually reducing your HP. Sure it will be small, but real none the less. If the engine has alot of blow-by the pressure will be significant and in the worse case your can may rupture and cause an engine fire !! Most cans are not designed for any significant level of positive pressure.

Catch cans with air filters are not legal. All air from the crank case/rocker must be ingested by the engine to meet modern ADRs.

Cheers

Robin.

[SCRIBR]

THAT IS 1 SEXY ENGINE BAY!

Top job mate.. looks like you have put alot thought and workmanship into your creation!

I tip my hat to you sir

[Ninka]

Well done

You obviously put a bit of effort into that separator!

[F6 UTE]

Looks very nice Robin!!.

[Slymeat]

M8 it looks really neat top work.

[xlnt6]

Thanks guys !!

Next on the agenda..... taking a page out of Allan's book. Dual Zone Climate Control. Always liked the look of the it and it wasn't an option back when I first got the car.

Cheers

Robin.

[bcl]

Excellent job Robin, looks professional, and far sturdier than what's usually avalable.

Well thought out as usual.

Perhaps you could go into business!

Brian

[ENVY-T]

As per usual, the work that comes out of anything to do with Nizpro is brilliant.

[F6 UTE]

Thanks guys !!

Next on the agenda..... taking a page out of Allan's book. Dual Zone Climate Control. Always liked the look of the it and it wasn't an option back when I first got the car.

Cheers

Robin.

←

I'm converting the ute next week!!!!!!!

[xlnt6]

Excellent job Robin, looks professional, and far sturdier than what's usually avalable.

Well thought out as usual.

Perhaps you could go into business!

Brian

Thanks Brian, don't know about going into business, I only started it 6 months ago !!! I made it out of material / parts that I already had (except the stainless wool), so I don't know how much it would end up costing to produce, probably way too much. So you coming down for the FPV day at all ???

I'm converting the ute next week!!!!!!!

I'm still gathering the bits needed, so don't know the timing as such. I'm just wondering what the dealer will say when I explain that I want to reprogram the BEM to suit DZCC, but not to reload the ECU/edit mapping. It's out of warranty, so I don't really care, but I don't want them to F.... it up.

Cheers

Robin.