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IAG AOS Review

179K views 228 replies 74 participants last post by  squaresandcubes  
#1 · (Edited)

I just want to say that me championing IAG products is having experienced first-hand the praiseworthy attention detail they put into their work and their relentless drive for perfection. I’m a staunch supporter for great Subaru shops to be recognized because I’m tired of seeing customers’ hard earned money wasted due incompetent work compounded by subpar customer service!

Firstly, everyone knows the benefits of an AOS/catch can but here are certain attributes they absolutely need to have:
1. 3 ports (one for each cylinder head and one for top of block). Reasoning being this allows for much efficient relief of crankcase pressure.

2.Coolant heated especially in colder climates or else this happens.


This is another reason why you DON'T want to go with the Grimmspeed AOS (Grimmspeed AOS and Cusco Catch Can After Track Review - YouTube)

There are certainly products out there have do fulfill the above criteria, but as I will go into, there are features of the IAG AOS that perches it atop the food chain. I mean why else would IAG bother even releasing an AOS with a market already inundated with AOS/catch cans?

The rather unassuming, plebian exterior of the IAG AOS belies the engineered intricacies of its internal guts:

1. Better oil separation than its competitors. This is the main idiosyncrasy of IAG’s design. Through painstaking testing and poring over the breathing characteristics of the EJ25, this is what they come up with.
  • No vacuum source allowing for slower movement of oil vapors through the can for greater separation.
  • Swirl pot design for slowing internal velocity.
  • Huge breather port to slow the vapors even more inside the can.
  • The superior coolant heated design ensures that the entire can is perfused by heat so condensation won't form in the oil you separate...which is important because you want the oil to be as pristine as possible going back into the engine!

2. The large capacity, up to 1L (Crawford holds 750mL), practically negates the possibility of having the AOS be brimming full of oil during hardcore tracking. Size comparison:
Image


3. Larger drainage port than its competitors so the AOS can empty the separated oil more efficiently back into the crankcase.

4. The ports are machined into the actual AOS, unlike Perrin which relies on Teflon tape for a seal which is known to break down. READ: Oil + hot engine = FIRE not to mention blatant oil loss (Perrin Air Oil Seperator Install/Review - Page 3 - NASIOC), more leaks: Leaking perrin AOS - NASIOC
more leaks: http://www.iwsti.com/forums/4079430-post38.html
More leaks: http://www.iwsti.com/forums/4079908-post40.html
more leaks: http://forums.nasioc.com/forums/showpost.php?p=43064317&postcount=69
Leaksssss everywhere: http://forums.nasioc.com/forums/showpost.php?p=43554374&postcount=105

Furthermore Perrin AOS O-rings needs to be inspected (http://www.rallysportdirect.com/catalog_photos/instructions/perrin/per1_psp_eng_606rd.pdf) whereas IAG uses Viton O-rings that not only withstand the harsh temperatures of the oil but also the potentially corrosive properties of oil (high chemical resistance).


5. Although maintenance-free, it is easily disassembled like Perrin for cleaning. You don't have this luxury with Crawford.

6. Just overall a high quality design, your $370 goes a long way!


7. AOS is better than a catch can. I’ve ran a Peterson catch can for 75,000 miles. Although I was desensitized to the smell, my passengers would comment on the smell of oil. The vapors would come out of the breather filter to condense to an oily film on my surrounding components, aside from looking like sheer filth it could also pose as a fire hazard. There is also the possibility of an oil catch can filling up entirely during hardcore cornering on the track, depriving the motor of all that sequestered oil.

8. IAG AOS will fit even with upgraded TMICs.

9. Why no vacuum source? The main reason is that the engine is under a positive pressure when you are boosting and a vacuum source is not really need while cruising. It also eliminates ANY possibility of any oil getting back into the intake system. The PCV system is really for emissions where it is not emission friendly to dump the vented gases into the atmosphere so they are rerouted back into the intake. As people who modified cars, we don't really care about emissions with our catless downpipe, do we :lol: The IAG AOS is built upon the lack of a vacuum source and it does its job extremely well :tup:

The new IAG AOS V2 will feature an optional vacuum source for those who adamantly want it :)

Comp vs street series - I would choose Comp if you have an upgraded turbo and/or on E85. Street series does decrease the amount of E85 vapors that are able to get into the oil which ultimately leads to drop in oil viscosity and lubrication. You should be changing your oil frequently when you run E85 anyway. E85 vapors are the lesser evil when compared with the higher potential of blowby you encounter with the street series while running bigger turbos/high boost.

10. IAG has the best coolant passage design to ensure that the ENTIRE CAN is perfused uniformly by warm coolant. This of course lessens the possiblity of sludge build up and prevents condensation formation. Perrin only has the base heated.

Image



Personally, this is what my throttle body looks like with 30psi of boost and 3000miles with the IAG AOS (dat pink meth). No smell of oil at all :tup:


so stealthy that the dealership will think it is the 2015 STi sound tube :lol:
Image


Further endorsement from Junior NASIOC - View Single Post - PTE6466 650+WHP Build E85 and

http://forums.nasioc.com/forums/showpost.php?p=44055425&postcount=223 (for you high boost people)
 
#6 ·
The vent to atmosphere is what the original IAG AOS is where the gases escape directly into the atmosphere and not back into the intake which also eliminates the vacuum source. This how the originally designed AOS was intended to do based on the points I illustrated in my post. Due to the increased clamor for a vacuum source and also some gripes about dumping the gases directly into the atmosphere, IAG obliged and are offering it as an option.

The Street Series will have a vacuum source and reroute the gases back into the intake.

The Comp Series will be the original VTA design :tup:
 
#8 ·
It provides a vacuum source on the crankcase which some believe helps create a better seal around the rings
 
#10 ·
IAG doesn't believe it does since they got rid of the vacuum source :lol: Just differing schools of thought
 
#14 ·
To add to this review, I just received my IAG AOS today in the new wrinkle red color! It looks great! The build quality on it is absolutely spectacular! The instructions I got off their site are also outstanding and very through. I will be installing it in the next few days when I get a chance. I would also highly recommend this AOS over all the others; it has the most thought out design for sure!:tup:

If you're wondering where to get it, I purchased mine from SMY Performance. I emailed Yanev before I placed my order to see if they had gotten them in yet and he said they got their shipment on Friday! Awesome vendor, will be doing business again with them in the future! :cool:





Like User said, contact IAG. But if you look at the AOS there are many holes along the length of it that are used to mount it to the bracket. I'm sure you could get it mounted fine and still use the strut bar... or just get rid of it the bar. It's not really necessary on these cars since the strut towers are located so close to the firewall.
 
#13 ·
Give IAG a call

You'll get way more function out of the AOS than the strut bar since strut bars don't do anything anyway :lol:
 
#16 ·
Do you think an AOS (this IAG one, for example) is a necessity when going stage 2 (only downpipe, protune, and maybe an intake)? I am stage 1 now, just CBE and Cobb OTS tune, car runs great and will be going stage 2 as described in the Spring. I have checked my IC for oil and it's bone dry. I'm very well aware of the purpose and function of an AOS, but is it something that should be added if symptoms are observed or when mileage gets high? Or should it just be a standard item that almost defines stage 2 like a DP, etc...
 
#18 · (Edited)
I bought and installed an IAG AOS 6 months ago or so and can attest to its usefulness. Hard to say that it is completely preventative, but I went from a tiny bit of oil residue in the IC to zero and when taking apart the AOS, there is a light film of oil inside. Definitely happier to see it there over being slurped back up into the engine.
 
#20 ·
I bought and installed an IAG AOS 6 months ago or so and can attest to its usefulness. Hard to say that it is completely preventative, but I went from a little oil in the IC to zero and when taking apart the AOS, there is a film of oil inside. Definitely happier to see it there over being slurped back up into the engine.
How is it doing in the cold? Lines gumming up at all?

I can't wait to order one of these. They seem to be the best solution for keeping oil out of the intake and in the case.
 
#25 ·
I'm putting in my IAG Competition AOS this thursday. My main concern is oil smell. This is my DD 90% of the time, and I definitely don't want my interior smelling like oil (especially since I could never get the burnt oil smell out of my previous car).

I'll give you guys updates after the install and probably again after a month of driving.
 
#27 · (Edited)
Well, I got the AOS installed tonight and there are some things to note for you guys with TMICs.

The larger hose that goes on the side of the AOS and the 1" hose were the hardest to route. In fact, the 1" hose could only be routed between the firewall the intercooler in such a way that it's incredibly hard to get the intercooler in place now. We first tried to route it down the passenger side (like the picture), but it kinked every time. I almost wish they'd gone with a smaller diameter hose for the top port or even two 1/2" hoses to give us more clearance around the intercooler. If the hoses were less prone to kinking this might be a non-issue, but they do not bent very far at all before completely collapsing. (I might look for a 45 or 90 degree elbow for the 1" hose so I can route it differently. Stay tuned.)

That said, the instructions are pretty much idiot-proof. I had a mechanic buddy helping me install it and he said the difficulty excluding the hoses was a 3/10, but the hoses made it a 6/10. You guys with a front mount won't have any trouble at all getting it installed because you'll have tons of room to work with.

Also, if you're worried about the AOS getting cold, don't. It was about 35degF outside and after a 30 min test drive I opened the hood and (like an idiot) touched the very top of the AOS and nearly burned my hand. I'd say it's heated plenty.

One thing to be careful of is the vacuum lines. They get hard and brittle with age and we accidentally broke one while routing the cables. Having some 4mm vacuum line on hand might be a good idea.


I'll update you guys after a week and then maybe again after a month to see how everything has been working.
 
#29 · (Edited)
Alright, before anyone says it, my engine bay really needs to be cleaned. But, I'll have to sort that out at a later date. In the meantime, here's a picture of the completed installation.

Image


Note the two hoses making contact with the intercooler (Top and Bottom corners on the left side of the intercooler). Those are the ones that kept kinking any other way I ran them. I don't really like them being right up against the intercooler, but I don't really see any other way to get it done.

I FORGOT TO MENTION, you will have to bend the bracket for the horn or relocate it in order for the AOS to fit. In its factory position, it is exactly where the AOS needs to go.

Also, Day 1:
I don't see any leaks around any of the connections and fluids are where they should be. That said, I did smell some fumes getting into the car, but I'm hoping it's just fluids burning off from installing the AOS last night. I drove to work with the windows down (in 45º weather :crying:) and left them cracked to air out. I haven't really gotten on it today because I'm worried about the hose. I'll update you guys again after I get the hose sorted out and have a chance to really test it. (See post #40: http://www.iwsti.com/forums/4097231-post40.html)
 
#32 ·
Alright, before anyone says it, my engine bay really needs to be cleaned. But, I'll have to sort that out at a later date. In the meantime, here's a picture of the completed installation.

Image Link


Note the two hoses making contact with the intercooler (Top and Bottom corners on the left side of the intercooler). Those are the ones that kept kinking any other way I ran them. I don't really like them being right up against the intercooler, but I don't really see any other way to get it done.

I FORGOT TO MENTION, you will have to bend the bracket for the horn or relocate it in order for the AOS to fit. In its factory position, it is exactly where the AOS needs to go.

Also, Day 1:
I don't see any leaks around any of the connections and fluids are where they should be. That said, I did smell oil getting into the car, but I'm hoping it's just fluids burning off from installing the AOS last night. I drove to work with the windows down (in 45º weather :crying:) and left them cracked to air out. I haven't really gotten on it today because I'm worried about the hose. I'll update you guys again after I get the hose sorted out and have a chance to really test it.
Based off of the picture, you should rotate the vent port 1 hole to point it more towards the rear of the car and route it next to the TMIC down next to the tranny...should not kink or anything.

OR you could upgrade TMIC and then there is a ton of room:D
 
#40 · (Edited)
Quick update. I have a boost leak due to a leaking intercooler hose. When I thought it was oil, I contacted IAG and they were willing to work something out if it is, in fact, the AOS producing the smell. It's great to know IAG stands by their products (kudos to Rick @ IAG for all his help).

Update #2: It's a fuel leak and a small boost leak. I apparently have a terrible sense of smell, but I think I was looking for a problem coinciding with the work that was just done and my brain filled in the blanks. It's somewhere around the drivers side fuel lines, and it's now leaking bad enough to make a small puddle beneath it.

Image
 
#41 ·
Yikes good thing you caught it, that's a fire hazard! Report back if you smell anything after you fix the fuel leak :tup:
 
#42 ·
so i'm working through what to do on this and have 2 quick questions which i'm hoping to get input (user?) on:

1. Is there data/info out there on how oil composition may or may not change between using a catch can system vs an drain back system? there is something about the idea of oil that has left the crankcase, traveled around an AOS system and then returned to the crankcase that makes me wonder if anything other than oil (fuel getting past the rings?) might be taking that same route and returning back into the case. Catch cans would prevent this but at the same time are a PITA. I'd think with the abundance of drain back systems on the market that the industry believes this is not an issue but i'm curious if there is more info out there that i've not been able to find.

User, any differentiation in fuel %age in your oil between the catch cans and the AOS? Anything else you noticed?

2. Anyone heard anything on the availability of the race version? As CNY_STI and I discussed on his thread, the ability to use AN fittings is VERY appealing.
 
#43 ·
I've done oil analyses on both catch cans and the AOS and there is no difference :tup: No drop in viscosity or contamination is evident. I would give IAG a call to see when they are releasing the race version, it is confirmed that they are 100% committed to releasing it
 
#54 ·
Not anymore. They replaced those 4 leaky fuel lines and that seems to have resolved the majority of the smell. I also had to reroute the 1" hose again because the dealership severely kinked it when they put the intercooler back on. It seems like the best way to do it with a TMIC is to run it up under the A/C line and let it drop down between the two metal pipes going to the intercooler. If drop it down closer to the AOS, the hose gets squashed by the metal pipe. If you do it farther over to the drivers side, the angle is too sharp and the hose kinks.

That said, I don't usually smell anything when I'm driving around. Occasionally, if I'm coming to a stop with the windows down, I do smell a tiny bit of oil. It's not enough or often enough to really worry me, though.
 
#51 ·
smh, please check your connections Perrin AOS users :(

NASIOC - View Single Post - Perrin Air Oil Seperator Install/Review

I purchased the aos about 6 months ago, didn't have the rtv yet. Oil has been leaking. Today I took my aos apart already had 6k+ miles with it, noticed the yellow sludge build up at the top intake return hose and in other areas. The aos it self was pretty nasty but excessive. Called Perrin, they sending me the fix with oil leak and regarding the sludge they didn't have much to say about it, he asked how I had it installed and said it was fine. BTW I live in Bakersfield Ca its been cold in mornings 45° and noon around 65-80. I think its the morning warm up causing the condensation build up and causing the sludge. I'll try and post pictures.



who knows if the IAG AOS may look the same? Although I think the IAG's coolant design may mitigate the kind of build up much better
 
#53 ·
who knows if the IAG AOS may look the same? Although I think the IAG's coolant design may mitigate the kind of build up much better

When I took the head vent lines off I had very little yellow junk build up. The oil return looked fine, and the vent. Once the weather is better im going to take it apart and check it out. I have about 13k on my aos too