How Important are Oil Management Measures with an '04 WRX

[LaszloT]

In the "Engine Building Tips From the Pros - Are EJ-Series Engines as Weak as Tuners Claim?" article I posted earlier, I recall Crawford Performance's comment:

"We highly recommend the use of an air/oil separator (AOS) on any turbocharged EJ motor to eliminate oil from coating both the intake tract and the inside of the intercooler, which causes a reduction in cooling efficiency that can cause detonation."

Read more: http://www.importtuner.com/tech/impp_1103_subaru_ej_series_engine_tech/viewall.html#ixzz2Rt4izb8V

Oil vapors in the intake tract also lower the effective octane of fuel, so this is another reason that suggests oil mgmt measures are important.

I found 2 mods that help manage crankcase oil, and wanted to know how important they might be to machine performance:

1. Grimmspeed AOS ($285), and
2. KillerB Oil Baffle and Windage Tray ($85).

What do you think?

[STeveD]

I'm not a fan of the Grimmspeed. Has it been redesigned yet?

http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/224508-grimmspeed-aos-vs-crawford-aos-review.html

I believe in Vent To Atmosphere... run the vent hose(s) under the car to the transmission or so and you should have minimal odour. However, your car may need a tune tweak to go VTA and idle smoothly.

Most of us are running the Cosworth baffle instead of the Killer B, especially with stock pans. Fair amount of labour involved in getting this done... are you planning for the engine rebuild?

http://www.rallysportdirect.com/Cosworth-Oil-Control-Baffle-Subaru-Turbo-Models-inc-2002-2011-WRX-STI

Edit: To be clear, the 2.0L oil pan design and stock baffling isn't the greatest. The Killer B windage tray, mounted that high, is still going to allow too much slosh and could uncover the oil pickup too easily. Plus, opinions on the design: http://forums.nasioc.com/forums/showpost.php?p=27383408&postcount=36

Whole thread: http://forums.nasioc.com/forums/showthread.php?t=1756427&page=2 Page 1 is mostly about pickups, not the pan. But you can see how the Cosworth baffle will help keep oil lower in the pan than the KillerB Windage Tray.

[LaszloT]

I thought the function of the windage tray and baffle was to strip the oil foam from the crankshaft to send it to the pan, rather than keep the oil from climbing up within the pan. Agree, it's an add for a rebuild - and there are no plans for that yet. I can take my time exploring available options.

Folks,
Does an AOS start to get important only when tracking the vehicle because you get more vaporized oil with high rpms? Or does the EJ205 2.0L have an oil spray system for cooling the pistons that contributes oil to crankcase vapors as well?

Here are some AOS's that are available :

1. IXIZ,
2. Crawford,
3. Grimmspeed, and
4. Moroso (pictures below).

[JoeT]

AOS get's more important in any motorsports application. Extended boost periods also increases the chance of blowby forcing crank case pressures to go up and forcing atomized oil through the system. Oil contains 0 resistance to ignition if ingested through the intake and burned, it effectively lowers the octane level of the fuel, which increases the chance of detonation.

Capturing oil before it goes into the intake is important.

Problem 2 with Boxer engines:

The oil return gallery is below the cylinders and contains no baffles preventing the oil from backwashing into the valve covers. When pulling high G's (greater than 1g) sustained, as in Turn 3 of mosport or Turn 8, oil can and normally does pool in the valve cover and gets forced up the valve cover vents, then into your intake. We use customized baffles in the oil pan to prevent this from occurring.

[LaszloT]

We use customized baffles in the oil pan to prevent this from occurring.

JoeT,
Would you have an image of those "customized baffles in the oil pan" you mentioned above, or is that so secret you might have to kill me if word got out? Ha ha.

I'm not going to be pulling sustained 1G+ in a Stage2 Rex on street tires anytime soon, so it's not an issue. But I do want to manage oil vapour that's heading to the intake charge and I am fascinated by advanced engine design.

[JoeT]

Sustained 1G is possible on streets on the REX. Plus "splash" from transitions can also force oil back up the gallery, which forces oil up into the intake through the valve cover vents. Next time you're cleaning up your engine, take off the little silicone connector between the intercooler and the throttle body, you maybe surprised at what you see and how much of it is in there.

As for the baffle, look up "Cosworth Oil Baffle" then picture a toilet seat (seriously), it's similar to the Cosworth baffle with the center cut out of it. Nothing wrong with the cosworth version, but the rubber fingers kind of prevent the oil from draining into the pan quick enough. That's my experience with it.

Hope this helps.

[STeveD]

To the top.

[LaszloT]

I can get an AOS for sure and a Cosworth oil baffle, but there was no interest in a custom baffle with the people I was working with when the motor was rebuilt.

But it sounds like you are also saying that WRX oiling upgrades are required or it's not suitable for anything but the lightest track duty. Is that so?

And should I also upgrade to the STi pan like in this flatirons kit (06-07 SUBARU STI OIL PAN AND PICK-UP)?

[dubya_rx]

My oil pan modified...

[LaszloT]

My oil pan modified...

Where can I get one of those, Walter?

[dubya_rx]

Frank made it when rebuilding my engine. Not sure if it's effective or not. I'll let others who know more about the theory comment.