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AOS vs Catch Can Reviews...


AOS Or Catch Can?  

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  1. 1. AOS Or Catch Can?



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Looking for reviews from those who have run either AOS systems or catch cans. Please include which brand/set-up you ran and your overall impression. Feel free to participate in the Poll above as well. Not really looking to turn this into one over the other but instead get some informed reviews about the various systems.
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I have a GS AOS system. I cheaped out instead of buying the Crawford system. It never hydro-locked, however, I had several "Oh shoot, how did I loose 5 quarts of oil in a 30 minute track session?" incidences.

 

The GS AOS has been responsible for several hydro-locked engines. If you drive on predominantly CCW tracks, avoid it like the plague. It drains to the oil fill point, and on a CCW, would have to run against the centrifugal force.

 

Probably the best setup I saw was on a high-hp STI that had the Crawford v2 AOS with a catch can. He was in the pit next to us, and would drain about half a water bottle of nasty yellowish crap out of the catch can every session.

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I have a GS AOS system. I cheaped out instead of buying the Crawford system. It never hydro-locked, however, I had several "Oh shoot, how did I loose 5 quarts of oil in a 30 minute track session?" incidences.

 

The GS AOS has been responsible for several hydro-locked engines. If you drive on predominantly CCW tracks, avoid it like the plague. It drains to the oil fill point, and on a CCW, would have to run against the centrifugal force.

 

Probably the best setup I saw was on a high-hp STI that had the Crawford v2 AOS with a catch can. He was in the pit next to us, and would drain about half a water bottle of nasty yellowish crap out of the catch can every session.

 

 

5 quarts??? Sheesh! Now imagine what you'd lose if your were actually fast!

 

 

Sent from my iPhone 5S, shutty

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Unless you are tracking the car, you are probably wasting your money.

 

If tracking the car, avoid the GS.

 

Crawford or Perrin. But even with those, you must dump into a catch can so you can empty it every session.

 

Dont hook up the coolant lines, unless you are using the device in a mis-application on a street driven car in cold climates. Irritates me to no end that a device that should be race only has been modified for dd use in cold climates (rant over).

 

Also, be brave and cut open a used Crawford AOS. Malted milk ball anyone?

 

Nothing is perfect. If it is a race car you will be doing maintenance every session anyway.

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I was planning on avoiding the GS. Heard too many horror stories...If I go AOS it will likely be Perrin or Crawford.

 

My uses are primarily a spirited DD but I may track on occasion once I'm content with where it's at. A tuner recommended it to me if I go with an e85 tune since I'd be shooting for somewhere near 350whp. I may just do the tune first and see check the intercooler periodically and go from there... Is that correct thinking of how would you gauge the "need"?

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Dont hook up the coolant lines, unless you are using the device in a mis-application on a street driven car in cold climates. Irritates me to no end that a device that should be race only has been modified for dd use in cold climates (rant over).

 

What about the theory of blow by / oil vapors in the intake contributing to a reduction in octane of gas? Even with a daily driver subaru, when you tune your car to perform optimally with a specific octane of fuel, anything that keeps that fuel pure and thus contributes towards a reduction of potential knock / detonation seems like a good idea. The addition of the coolant lines functions to make it applicable for a daily driver instead of just a racecar.

 

Like you say--is it perfect? Probably not. But is it functional? Seems to be... :iam:

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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Anytime, anywhere...

 

 

I wish you were a little closer, buddy, I'm thinking I might actually give you a run for your money. ;)

 

Anyhow, I thought that the Perrin & Crawford AOS systems came with integrated OCC's. Do they not?

 

 

Sent from my iPhone 5S, shutty

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read this exhaustive thread on the subject:

http://www.iwsti.com/forums/2-5-liter-litre-factory-motor/146699-official-sti-engine-venting-o-separators-catch-cans-thread.html

 

It explains the logic, and how to build a good catch can system out generic cans. You basically need a two-can system, one for the VC breathers (which are two way) and one for the PCV that eliminates the manifold connection (basically what a crawford does minus coolant heating and oil return).

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What about the theory of blow by / oil vapors in the intake contributing to a reduction in octane of gas? Even with a daily driver subaru, when you tune your car to perform optimally with a specific octane of fuel, anything that keeps that fuel pure and thus contributes towards a reduction of potential knock / detonation seems like a good idea. The addition of the coolant lines functions to make it applicable for a daily driver instead of just a racecar.

 

Like you say--is it perfect? Probably not. But is it functional? Seems to be... :iam:

 

If it was that bad there would be one from the factory. How do so many Subies live without one??? :confused::confused::confused:

 

You sir have bought the hype. :wub:

 

Yes it can happen. Yes it does happen. But the extent and actual detriment caused is blown WAY out of proportion by the interweb and a single company grasping at straws to stay relevant and in operation.

 

One of the gents who actually wrote all the hype tunes on my dyno. Guess what he thinks of them....??? :rolleyes:

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If it was that bad there would be one from the factory. How do so many Subies live without one??? :confused::confused::confused:

 

You sir have bought the hype. :wub:

 

Yes it can happen. Yes it does happen. But the extent and actual detriment caused is blown WAY out of proportion by the interweb and a single company grasping at straws to stay relevant and in operation.

 

Fair enough. I'm still likely going to install mine because I want to ditch the PCV and see if I can't eliminate adding 1/2qt of oil or so during each OCI.

 

One of the gents who actually wrote all the hype tunes on my dyno. Guess what he thinks of them....??? :rolleyes:

 

^^I don't get what your trying to say. That Bill conjured up a bunch of need for a part that you're now saying is useless? :confused::lol:

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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Mike - you could create a package deal - crawford AOS, GS MBC brace, and Front/rear strut braces. Advertise as best upgrades to LGT. You could charge a fortune and retire early.

 

/snark

 

LOL. :lol::lol::lol:

 

Yeah and retire to a warm weather country with no extradition treaty where I can sip drinks from coconut shells with little umbrellas in them.

 

Losing 1/2qt per oil change is nothing. If the device makes you feel better, than it has value to you. Nothing wrong with that. But... we ran over 25 track days on a stock block with no oil cooler or AOS and guess what? Car is back on the track for season 2 with the exact same stock block.

 

Yes we added an AOS now (no coolant lines hooked up). Because we are planning to build the motor this season and push it FAR harder than 99.97% of owners ever will. Closing the deck and shooting for 30psi-32psi. That and we are seeing lots of blow by now as the motor wears out and we are finally losing enough oil between sessions to warrant it.

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Even though there's not much special about the crawford on the inside (or any other AOS for that matter, apparently)--I'm just generally a big fan of parts the FIT. I'm willing to pay decent money for precut hoses, fit and finish, etc--I just don't have time to deal with *good* installs, much less the bullshit-pull-your-hair-out ones.

"Bullet-proof" your OEM TMIC! <<Buy your kit here>>

 

Not currently in stock :(

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