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Old 01-11-2021, 08:07 PM   #1
mgrotel
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Default IAG AOS - Street or Comp

I have read several perspectives on this topic, and cannot for the life of me decide which route to go. Setup is sub 500whp on mustang dyno, 2006 wrx. Street driven fun car, not my daily, mostly a cruiser, but get on it more than when I am driving the daily. No tracking, just a get out of the house and have some fun type of car. Flex fuel kit, will be on e85 90% of the time.

Street - pulls vapors out of crankcase better so oil doesn't get diluted as quickly, but still going to get some nasty stuff into the turbo inlet.

Comp - keeps turbo inlet 100% clean, but oil will get diluted quicker based on running e85 most of the time and there is no vacuum pulling those vapors out.

For me, it comes down to which one I consider the lesser of the two evils. Do I put up with 1500 mile oil changes and have a super clean intake charge, or do I have the oil last longer and put up with knowing some crap is still going into the intake.

Would love to hear some thoughts on this, thanks.
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Old 01-11-2021, 09:40 PM   #2
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I was sick of the the smell from my IAG comp. series so I decided to try the Killer B AOS. (Yes, I know I could have easily converted to the street series.) But honestly none of the AOS's are 100 percent, so I'm probably just going to add a catch can inline to help catch what the AOS misses. I have lots of room on the passenger side of the engine bay now that I don't have a Cobb Air Box there.
Not that there is an answer to your question there, but I had the same thoughts and this is what I came up with.

Cheers.
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Old 01-11-2021, 09:51 PM   #3
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How far down and back did you route the comp breather hose?
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Old 01-11-2021, 10:03 PM   #4
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Quote:
Originally Posted by mgrotel View Post
How far down and back did you route the comp breather hose?
it was pretty far back, I think I used the full length of hose. but its comes up the transmission tunnel and gets sucked in the HVAC inlet.
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Old 01-11-2021, 10:56 PM   #5
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Have you thought about running neither? Back when Bush was in the White House, we ran out cars without these and all was well on earth. Then drainbacks came out. Then crude AOS that were for other cars. Now they are all purdy. Any people still blow up their cars at the same rate. Its not a requirement.
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Old 01-12-2021, 12:24 AM   #6
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Its a requirement for me considering I just pulled my turbo inlet off and it was absolutely disgusting inside and likely the reason cylinder 4 had scoring on the wall. Its never been an issue in the past since emissions wasn't a thing and we could just dump it on the ground. I think I am talking myself into the comp series LOL
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Old 01-12-2021, 12:26 AM   #7
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I'm tempted to just not use the 1" hose and put a small breather filter on the can, but that might make a mess. I think best case would be to find a way to route that 1" hose back into the exhaust and let it burn off.
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Old 01-12-2021, 10:13 AM   #8
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Quote:
500whp on mustang dyno, 2006 wrx
Sweet Jesus, start saving up for a new tranny if you are pushing that much power on the 5 speed.

Back on topic, I would rather have a clean intake and change my oil more frequently.
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Old 01-12-2021, 11:41 AM   #9
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6 speed swapped
And I'm thinking the same thing
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Old 01-12-2021, 11:53 AM   #10
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When I was speaking to my shop, they said that generally you run a street series when on E85, otherwise they run the Comp. Is this what your research came up with as well?
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Old 01-12-2021, 12:13 PM   #11
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6 speed swapped
Ok, thats better haha
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Old 01-12-2021, 01:59 PM   #12
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When I was speaking to my shop, they said that generally you run a street series when on E85, otherwise they run the Comp. Is this what your research came up with as well?
Yea, I just don't like the idea of some oil making it back in the intake. I guess I'm skeptical that some wouldn't still get in there. IAG says with sub 600whp and e85 to use street, but anything over 600whp should be comp. People I've talked to its about 50/50. I keep going back and forth.
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Old 01-12-2021, 02:17 PM   #13
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Yeah, completely understand.

Personally, I think venting to atmosphere is a 'cop-out' for AOS' designed that way. Is it really doing it's job as an air-oil separator if it needs to VTA in order to ensure the intake track doesn't get blowby?

Good luck on your decision. You can't go wrong either way. But it does seem like you have a solution with the catch can addition.
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Old 01-12-2021, 07:06 PM   #14
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Decision made, going comp with a really long breather hose towards the rear bottom of the car.
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Old 01-12-2021, 11:48 PM   #15
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What about replacing that 1" hose off the top with a small breather filter? Have a picture and it fits fine but the site won't let me attach a picture.
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Old 01-14-2021, 11:18 AM   #16
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Quote:
Originally Posted by mgrotel View Post
What about replacing that 1" hose off the top with a small breather filter? Have a picture and it fits fine but the site won't let me attach a picture.
Better than just running a hose IMO as you're not going to draw in unfiltered air under vacuum. Although, there will still be a smell, and anything nearby on the engine bay will get an oily sheen that dust/dirt eventually will start to stick to.
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Old 01-14-2021, 12:54 PM   #17
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Better than just running a hose IMO as you're not going to draw in unfiltered air under vacuum. Although, there will still be a smell, and anything nearby on the engine bay will get an oily sheen that dust/dirt eventually will start to stick to.
Good point, maybe go back to the long hose and just put a check valve at the end. That way unfiltered air can't get it and yet air can still get out. I would check that valve for operation each oil change. Thoughts?
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Old 01-14-2021, 03:27 PM   #18
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Quote:
Originally Posted by mgrotel View Post
What about replacing that 1" hose off the top with a small breather filter? Have a picture and it fits fine but the site won't let me attach a picture.
Quote:
Originally Posted by mgrotel View Post
Good point, maybe go back to the long hose and just put a check valve at the end. That way unfiltered air can't get it and yet air can still get out. I would check that valve for operation each oil change. Thoughts?
I wouldn't. Check valves require spring pressure to seal; 1/2 - 2psi typically, which means you'd always have some pressure in the crankcase. Being VTA you're already going to have some and adding a check valve will only compound that.

Bigger check valves made for higher flow, which is what you'd need here, are going to have higher spring pressure or be pricey.
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Old 01-14-2021, 06:05 PM   #19
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In what situation would the crankcase have a vacuum to suck air into the breather hose?
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