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Old 02-28-2013, 01:56 PM   #7051
340Duster
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Originally Posted by Jdub.csu View Post
Where do you think lots of the moisture ends up? In the oil pan..
The ethanol absorbs fuel in the tank/ lines, if it is introduced into the engine, it's most likely exiting via the exhaust as vapor. You really don't get that much fuel of any kind into your oil, unless your car isn't tuned right. I could maybe see it on cold startups with E since it has to run super rich to crank.

I mailed off the sample today, so I'll post back with the report.
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Old 02-28-2013, 02:55 PM   #7052
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I can tell you that even changing my oil every 3000 miles (using Rotella T6) and having a VTA catch can setup installed, the oil would have a nice hint of ethanol smell to it when I would change it.

Think about the fact that even at idle, your ethanol afr is actually about 9.8:1, and when you tune for power or for cold starts you are going close to 7:1. With 7:1 afr, you don't think that some fuel is making it into places where it normally wouldn't?
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Old 02-28-2013, 03:10 PM   #7053
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I had the ethanol smell in my oil when I was running an AOS. Since switching to a catch can setup, its been a lot better. My catch cans fill up with a yellow liquid that smells like corn and is non-flammable.

I am strongly considering switching to a exhaust based venting system like a few others seem to have done successfully. They use the exhaust flow to draw a vacuum on the crankcase so any vapor would burn off in there rather than having to be collected or returned to the oil.

I switched to a catch can system because I subscribed to the theory that you don't want this stuff in your oil but I don't like having to empty and clean the catch cans.

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Old 02-28-2013, 03:30 PM   #7054
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Ever have a oil analysis squids?
Yeah, i always run either Royal Purple Race oil or the Motoul. Have only had one oil analysis since i switched to E85 and it really was not that different than before i switched. Most of the people i talk to that have it done regularly havn't seen any more oil contamination frm E85 than they have from Gasoline. Some of them say that the prominent elements are different than on Gasoline, but they are in a safe range in both cases. Viscocity is the one thing i really pay attention to, and i have never had any issues with 5000 mi (or three racing events, whichever comes first) changes in that area.

Mine didn't really show much difference with E85 than it did with Gasoline. Slight drop in detergents (calcium) and everything else looked pretty much the same as it did before. If i wasn't in the middle of building a new house and had half my life in storage, i would take a look at it to refresh my memory.

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They're a very good idea if not a necessity! I agree with squidz and amalgrover on this. My personal preference is with the closed loop system of the coolant heated Crawford AOS. It deletes the PCV and does what it's supposed to do which is keeping the intake air tract clean. The coolant heating of the can keeps the condensation at bay in the can so that the oil it does collect drains back into the crankcase without gunk from condensation. You can monitor blow by and oil consumption with a visual of the exhaust smoke and your dipstick. I would steer clear of the oil filler top AOS's like the Grimm and the Prova, they don't work and can actually cause excessive crank case pressure which will cause seals in other components to go bad. I know this from personal experience.
I have the Grimmspeed AOS, and have no compaints or issues with it so far. About 10K on my built motor on E85 and have no unusual oil consumption or problems of any kind. The car sees track duty in autocross, drag racing, and HPD events at least 2-3 times a month as well.

I'm not trying to discount your experience with them...I just don't see that there is really any way, if they are hooked up right for them to cause excessive crank case pressure. They simply hook inline inbetween the existing PCV system and the intake to catch the oil vapors before they are returned to the intake. If the PCV valve is in place and properly functioning, then it wouldn't be possible for pressure from the filler to get pushed into the crankcase.
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Old 03-01-2013, 12:43 AM   #7055
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Originally Posted by Squidz View Post

Yeah, i always run either Royal Purple Race oil or the Motoul. Have only had one oil analysis since i switched to E85 and it really was not that different than before i switched. Most of the people i talk to that have it done regularly havn't seen any more oil contamination frm E85 than they have from Gasoline. Some of them say that the prominent elements are different than on Gasoline, but they are in a safe range in both cases. Viscocity is the one thing i really pay attention to, and i have never had any issues with 5000 mi (or three racing events, whichever comes first) changes in that area.

Mine didn't really show much difference with E85 than it did with Gasoline. Slight drop in detergents (calcium) and everything else looked pretty much the same as it did before. If i wasn't in the middle of building a new house and had half my life in storage, i would take a look at it to refresh my memory.

I have the Grimmspeed AOS, and have no compaints or issues with it so far. About 10K on my built motor on E85 and have no unusual oil consumption or problems of any kind. The car sees track duty in autocross, drag racing, and HPD events at least 2-3 times a month as well.

I'm not trying to discount your experience with them...I just don't see that there is really any way, if they are hooked up right for them to cause excessive crank case pressure. They simply hook inline inbetween the existing PCV system and the intake to catch the oil vapors before they are returned to the intake. If the PCV valve is in place and properly functioning, then it wouldn't be possible for pressure from the filler to get pushed into the crankcase.
I'm not about bashing vendors but I ran a GS AOS from its inception, I was a beta tester on this program. They're way too small to effectively do the job. I know how to plumb them and tested all the upgrades. I ran that AOS way to long and it caused excessive blow by which blew seals in my turbo. I tested my motor at regular intervals and it was healthy, 150 psi and <10% leak-down in all cylinders up until I pulled it off. Don't leave it on too long as you may regret it.

Like I said I'm not here to bash but I know what works for me. The Crawford AOS is the best designed unit in the group and it works as it should. You also don't need the PCV. It only works under vacuum and the Crawford AOS works in all conditions.

JMHO
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Old 03-01-2013, 09:32 AM   #7056
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Again, i'm not discounting your experience with the AOS. I also tested this product from the beginning, and have had it on my car for a while. I just don't see how any AOS could cause excessive pressure that was enough to blow out a turbo seal...

My question is how can the grimspeed AOS, if properly installed, allow more crankcase pressure? Where is it coming from? I mean they all work pretty much the same way. The lines on my grimspeed AOS are the same size as the ones on the dozens of Crawford AOS i have installed (which, i agree is an awesome part, by the way). They install in pretty much the same way as well.

I'm not saying it didn't happen, i just want to understand why/how.
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Old 03-01-2013, 02:28 PM   #7057
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I had a discussion with GS back when they were doing the development of the AOS. I told them it wouldn't work. I told them that the idea was silly because the fill cap is the same place in the pcv system as the breathers on the valve cover. Their testing showed otherwise. I can only think that the small gain in oil filtration comes from the fact that the fill cap is up and out of the way of the splashing oil in the valvetrain.

Regardless, on modified cars, it isn't a proper solution IN MY OPINION. We refuse to install them on customer cars because we feel they provide no benefit.
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Old 03-01-2013, 02:59 PM   #7058
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I had a discussion with GS back when they were doing the development of the AOS. I told them it wouldn't work. I told them that the idea was silly because the fill cap is the same place in the pcv system as the breathers on the valve cover. Their testing showed otherwise. I can only think that the small gain in oil filtration comes from the fact that the fill cap is up and out of the way of the splashing oil in the valvetrain.

Regardless, on modified cars, it isn't a proper solution IN MY OPINION. We refuse to install them on customer cars because we feel they provide no benefit.
what do you feel the best solution is?
have you installed any of the exhaust based crank case evacuation systems?
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Old 03-01-2013, 03:03 PM   #7059
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Please don't misunderstand...i'm not trying to argue with anyone, just trying to get more than opinion. I have one on my car and have seen it work flawlessly both on the street and in the many competition settings (Autocross, Road Racing, Drag Racing) that i use my car in. I have also been using it for well over 15K miles. Just trying to get some answers as to why the difference in results and where this percieved pressure comes from.
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Old 03-01-2013, 03:17 PM   #7060
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Originally Posted by Squidz View Post
Please don't misunderstand...i'm not trying to argue with anyone, just trying to get more than opinion. I have one on my car and have seen it work flawlessly both on the street and in the many competition settings (Autocross, Road Racing, Drag Racing) that i use my car in. I have also been using it for well over 15K miles. Just trying to get some answers as to why the difference in results and where this percieved pressure comes from.
I had one on my car for a while to. It seemed to work find for daily duties but have you ever pulled off the intake port hose after an autocross or track session? I'm almost certain you'll find that oil vapor has made it past the AOS and into that line.

Also, it would benefit you to read up on how the entire breather system works both under vacuum and boost. Air flow needs change under boost and you'll see why connecting the crankcase port to the valve covers and routing them back to the valve cover again (oil filler neck) isn't a good idea. You have all the flow at this point trying to push through the aos into one port back to the intake.

Another down fall of the GS AOS is that it doesn't take the PCV on the intake manifold into account. This is the strongest vacuum source when you are cruising so oil vapor can get pulled into the manifold directly via the PCV. Take your throttle body off some time and peak inside the manifold. I bet you'll see some oil residue at the bottom where the PCV is tapped.

I'm not saying you should ditch your AOS and that it is going to cause you issues on your setup. I'm just trying to help explain why myself and others don't think the GS AOS is the best option and what its down falls are.
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Old 03-01-2013, 03:51 PM   #7061
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Fair enough. I know how the breather system works. I'm a Subaru/ASE Master Tech and teach at an automotive college. What i'm missing is how that relates to running from the crankcase, to the valve covers, then immediately to the valve covers again (Oil filler) creates the kind of pressure they are talking about. connecting the valve cover to the valve cover to allow the oil to drop back into the head (crankcase) doesn't create pressure.

It does take the PCV into account, it keeps it in place as designed to keep pressure and oil from getting back into the intake. I have had my entire car apart. It doesn't smoke so there isn't any oil in the intake...I regularly pull my AOS apart after a track day and autocross and found the exact same amount of oil vapor as i have found on the dozens of catch cans and Crawford AOS i regularly service. I actualy just went out to the parking lot and checked it again...nothing.

I'm just not understanding how the pressure is getting in there to cause blowby. I can understand the argument that the AOS is small on these types of setups...but i don't see how that makes them useless. I could speculate that if you were running a considerable amount of boost (well over 25-26 psi) that the smaller size of the Grimspeed AOS could reduce it's effectiveness...but that is true for any AOS. Which is why high boost cars usually want to go with a catch can instead.

Last edited by Squidz; 03-01-2013 at 04:10 PM.
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Old 03-01-2013, 04:06 PM   #7062
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To you gys who are running coppers. What kind of lifespan are you getting out of them. My mileage is **** right now and I think the plugs are dying. Fuel trims are normal.
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Old 03-01-2013, 04:09 PM   #7063
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Originally Posted by Squidz View Post
Fair enough. I know how the breather system works. I'm a Subaru/ASE Master Tech and teach at an automotive college. What i'm missing is how that relates to running from the crankcase, to the valve covers, then immediately to the valve covers again (Oil filler) creates the kind of pressure they are talking about. connecting the valve cover to the valve cover to allow the oil to drop back into the head (crankcase) doesn't create pressure.

It does take the PCV into account, it keeps it in place as designed to keep pressure and oil from getting back into the intake. I have had my entire car apart. It doesn't smoke so there isn't any oil in the intake...I regularly pull my AOS apart after a track day and autocross and found the exact same amount of oil vapor as i have found on the dozens of catch cans and Crawford AOS i regularly service. I actualy just went out to the pakring lot and checked it again...nothing.

I'm just not understanding how the pressure is getting in there to cause blowby. I can understand the argument that the AOS is small on these types of setups...but i don't see how that makes them useless. I could speculate that if you were running a considerable amount of boost (well over 25-26 psi) that the smaller size of the Grimspeed AOS could reduce it's effectiveness...but that is true for any AOS. Which is why high boost cars usually want to go with a catch can instead.
Like I said, the GS AOS might work great on your setup and other people's as well. I just found that at my power level and usage, it wasn't doing what I needed it to.

It also most certainly does not take the PCV into account. On top of the crankcase ports sits a plastic valve. The bottom connects to the crank case port, the top connects to the inlet pipe and the side which contains the PCV connects to to the intake manifold under the throttle body. Under the vacuum, the throttle body draws on the crank case through the PCV on the side of this plastic valve. Under boost, the PCV closes and the crank case is only vented from the inlet through the top of the plastic valve. The GS AOS connects to the top of this plastic valve so it does "separate" during boost conditions where the PCV is closed but while under vacuum the intake manifold has a much stronger draw than the inlet does so most crank case vapors are being drawn straight into the manifold.

On my moroso twin can setup, one case catches for the valve covers and the other can catches between the intake manifold and PCV and I can assure you it catches a lot of oil and fuel byproduct.

Pressure gets past the rings, and moves into the crankcase and needs somewhere to go. If it can't get out the crank case port it flows up into the heads out out the valve covers. Routing all these ports together into one small unit seems to be the issue, at least at higher power levels or more extreme conditions. I've read up a lot on this subject from some of the great minds on these forums and this is the understanding I gained from that.

Edit: Adding a pic for reference:

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Old 03-01-2013, 04:11 PM   #7064
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To you gys who are running coppers. What kind of lifespan are you getting up of them. My mileage is **** right now and I think the plugs are dying. Fuel trims are normal.
I think we had this conversation before... but how much boost are you running and what kind of power are you making?

Have tried running standard iridium plugs with a smaller gap?
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Old 03-01-2013, 04:31 PM   #7065
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Like I said, the GS AOS might work great on your setup and other people's as well. I just found that at my power level and usage, it wasn't doing what I needed it to.

It also most certainly does not take the PCV into account. On top of the crankcase ports sits a plastic valve. The bottom connects to the crank case port, the top connects to the inlet pipe and the side which contains the PCV connects to to the intake manifold under the throttle body. Under the vacuum, the throttle body draws on the crank case through the PCV on the side of this plastic valve. Under boost, the PCV closes and the crank case is only vented from the inlet through the top of the plastic valve. The GS AOS connects to the top of this plastic valve so it does "separate" during boost conditions where the PCV is closed but while under vacuum the intake manifold has a much stronger draw than the inlet does so most crank case vapors are being drawn straight into the manifold.

On my moroso twin can setup, one case catches for the valve covers and the other can catches between the intake manifold and PCV and I can assure you it catches a lot of oil and fuel byproduct.

Pressure gets past the rings, and moves into the crankcase and needs somewhere to go. If it can't get out the crank case port it flows up into the heads out out the valve covers. Routing all these ports together into one small unit seems to be the issue, at least at higher power levels or more extreme conditions. I've read up a lot on this subject from some of the great minds on these forums and this is the understanding I gained from that.
Well...that's not the way all of the boosted Subarus are setup. Even though they all work the same. For example, my PCV valve is actually screwed into the intake manifold, not part of the plastic piece that conects to the crank vent. Either way, they all work in the same manner...

You are correct about how the PCV works..under bost it's closed, forcing the crankcase to vent to the AOS (as it should be) and under vaccum, it's open and pulling crankcase vaccum. However, since we are under vaccum, there shouldn't be any pressure in the crankcase anyway. I actually don't agree that the manifold has more vaccum than the intake does...if the lines are the right size, everything here should work fine, just as it does in stock form.

As far as the pressure getting into the heads...it sounds more like you are overloading the flow capabilities of your Crank vent than the AOS is causing pressure in the system. When the pressure is pushed into the valve covers (and i completely agree that it could be if your vent is not sufficient to handle the pressure, why you have that much pressure in the crank in the first place...well, that's a whole other issue) it has to go somewhere, and it should go back to the AOS...don't all AOS connect to the valve covers? Meaning that every AOS would allow this pressure from the heads to get back into the AOS? Isn't that what it should do?

If you are saying simply that the filler-top style ones are too small and limit the flow of all this pressure, then again, i see what you are saying that the smaller size of the Filler-top style units and would have to agree that if you had a LOT of crankcase pressure (which you really shouldn't have), or were running a lot of boost then the AOS isn't for you...but that still applies to all AOS, not just the filler types. Again bringing us back to saying that high boost cars need to use catch cans like yours.

My problem is people are saying that the filler-top AOS are 'causing' blow-by and 'causing' pressure and whatever...when that isn't really the case. It's simply a case of your setup being to big for the part.

Other than that issue, i completely agree that high-boost or big turbo applications (a.k.a high CFM) need to be running a catch can...and not an AOS.

Last edited by Squidz; 03-01-2013 at 04:39 PM.
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Old 03-01-2013, 04:43 PM   #7066
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Originally Posted by Squidz View Post
Fair enough. I know how the breather system works. I'm a Subaru/ASE Master Tech and teach at an automotive college. What i'm missing is how that relates to running from the crankcase, to the valve covers, then immediately to the valve covers again (Oil filler) creates the kind of pressure they are talking about. connecting the valve cover to the valve cover to allow the oil to drop back into the head (crankcase) doesn't create pressure.

It does take the PCV into account, it keeps it in place as designed to keep pressure and oil from getting back into the intake. I have had my entire car apart. It doesn't smoke so there isn't any oil in the intake...I regularly pull my AOS apart after a track day and autocross and found the exact same amount of oil vapor as i have found on the dozens of catch cans and Crawford AOS i regularly service. I actualy just went out to the parking lot and checked it again...nothing.

I'm just not understanding how the pressure is getting in there to cause blowby. I can understand the argument that the AOS is small on these types of setups...but i don't see how that makes them useless. I could speculate that if you were running a considerable amount of boost (well over 25-26 psi) that the smaller size of the Grimspeed AOS could reduce it's effectiveness...but that is true for any AOS. Which is why high boost cars usually want to go with a catch can instead.
I'm not looking to argue either but relaying my experience with this piece. I think because they are so small compared to a good catch can and where they are located on the filler top that they get overwhelmed very easily. They may work fine at stock boost levels but at higher boost 21+ psi they just can't keep up and actually create excessive crankcase pressure at higher boost levels. I had one the original beta test one with the knurled top cap and all the fitting upgrades for way too long probably 50k on a healthy well cared for motor and I'm sure it contributed to the turbo seal degradation!

I'm sure your 15k motor is tight and does not need much now but keep an eye on it. As far as the PCV which only works in a vacuum, if you pull off the TB and look into the intake you will find oil accumulated there. I don't want to beat this into the ground but I like that the Crawford eliminates it and it all runs thru the can. It works on vacuum and in boost and handles higher boost levels very well on most set ups.
JMHO
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Old 03-01-2013, 04:46 PM   #7067
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Squidz, I think we're mostly in agreement on things. I think the GS AOS works fine for DD duties. I think it keeps some oil out of the intake track and I don't see why it would cause issues on lower power setups that are mainly daily driven.

The only thing you said that I think you are wrong on is that the manifold doesn't pull a much stronger vacuum than the inlet does during light cruise conditions. At low throttle opening conditions, I believe there is usually going to be a much stronger vacuum on the intake manifold side.

Another thing to add to this is that at least on my plastic valve, there is actually only a tiny hole that allows airflow up to the top portion of the valve that connects to the inlet. I think this is another reason that most of the air flow during cruise goes from the crank case port to the pcv to the intake manifold.

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Old 03-01-2013, 04:51 PM   #7068
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Quote:
Originally Posted by Squidz View Post
Well...that's not the way all of the boosted Subarus are setup. Even though they all work the same. For example, my PCV valve is actually screwed into the intake manifold, not part of the plastic piece that conects to the crank vent. Either way, they all work in the same manner...

You are correct about how the PCV works..under bost it's closed, forcing the crankcase to vent to the AOS (as it should be) and under vaccum, it's open and pulling crankcase vaccum. However, since we are under vaccum, there shouldn't be any pressure in the crankcase anyway. I actually don't agree that the manifold has more vaccum than the intake does...if the lines are the right size, everything here should work fine, just as it does in stock form.

As far as the pressure getting into the heads...it sounds more like you are overloading the flow capabilities of your Crank vent than the AOS is causing pressure in the system. When the pressure is pushed into the valve covers (and i completely agree that it could be if your vent is not sufficient to handle the pressure, why you have that much pressure in the crank in the first place...well, that's a whole other issue) it has to go somewhere, and it should go back to the AOS...don't all AOS connect to the valve covers? Meaning that every AOS would allow this pressure from the heads to get back into the AOS? Isn't that what it should do?

If you are saying simply that the filler-top style ones are too small and limit the flow of all this pressure, then again, i see what you are saying that the smaller size of the Filler-top style units and would have to agree that if you had a LOT of crankcase pressure (which you really shouldn't have), or were running a lot of boost then the AOS isn't for you...but that still applies to all AOS, not just the filler types. Again bringing us back to saying that high boost cars need to use catch cans like yours.

My problem is people are saying that the filler-top AOS are 'causing' blow-by and 'causing' pressure and whatever...when that isn't really the case. It's simply a case of your setup being to big for the part.

Other than that issue, i completely agree that high-boost or big turbo applications (a.k.a high CFM) need to be running a catch can...and not an AOS.
youve stated exactly what everyone is trying to prove, the cars that run these AOS are not stock (for the most part) and a high percentage of them are running higher boost and are at higher power levels, and this AOS is not designed to handle that.
you said it your self the crank case presure is over-running the stock breather system.
the pressure finds the next path to escape the valve covers. that's why the filler neck style AOS dont work in these applications.
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Old 03-01-2013, 05:09 PM   #7069
manitou
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Sorry but one last bit of info from me on this and it's an important one which I forgot to mention. When I suspected the GS AOS was not working on my build I decided to conduct a test to find our what was going on. I placed a larger Greddy catch can in series with but after the GS unit and I was blown away at how much oil and water, mostly oil from condensation was in the can after a month. It was 3/4 full on a motor that tested at 150 psi compression and <10% actually closer to 7% average leak down in all 4 cylinders after I pulled the GS unit off. I love most of there other products and they are great to deal with. I still have a bunch of there stuff on my current build!

After that I pulled it off and installed the Crawford after researching what I found most on NASIOC liked.
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Old 03-01-2013, 05:21 PM   #7070
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Originally Posted by WRXt4cy View Post

I think we had this conversation before... but how much boost are you running and what kind of power are you making?

Have tried running standard iridium plugs with a smaller gap?
22 lbs of boost and about 330whp.
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Old 03-01-2013, 05:30 PM   #7071
WRXt4cy
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Originally Posted by sackytar View Post
22 lbs of boost and about 330whp.
Any reason why you are running coppers then? Stock plugs with stock gap should work just fine for you.
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Old 03-03-2013, 01:50 PM   #7072
Squidz
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Originally Posted by jnorth85 View Post
youve stated exactly what everyone is trying to prove, the cars that run these AOS are not stock (for the most part) and a high percentage of them are running higher boost and are at higher power levels, and this AOS is not designed to handle that.
you said it your self the crank case presure is over-running the stock breather system.
the pressure finds the next path to escape the valve covers. that's why the filler neck style AOS dont work in these applications.
Well, my car runs perfectly at 430+ whp and 23 PSi with this type of AOS on it. If you consider that low boost, then we are on the same page. Also, as stated before, my car is not just a daily driver. My car sees competition use 2-3 times a month...still with no issues.

The other issue, is that the the later cars run the smaller hole (with the PCV in the plastic piece), as shown in the picture above. My car does not, it's an 03 and runs the PCV in the manifold. I agree that this is a problem for those guys with the smaller hole in the port...how do other systems make this any better?

My problem is that people keep blaming the parts. "This part blew up my car"...whatever. It's about understanding what the parts can and can't do. I think it's the case of people using the wrong part, or using the part incorrectly, than an issue with the part itself.

I think many people overestimate what an AOS can and should do. You put a catch can behind any AOS, you will get stuff in it, as you stated. Yes, even the mighty Crawford (like the one we used on our land-speed car) would fill up our catch can after a while. AOS are designed to reduce the amount of blowby that gets back to the intake, not completely eliminate it. the only way to completely eliminate it is to not return anything to the intake (a.k.a catch can). As far as the AOS creating pressure and hurting things...that could happen with all of them....they all connect the heads to the crankcase vent...and if your crankcase pressure overloads your port, the pressure will go into the heads and get back to the AOS...the pressure would be the same no matter what...so the AOS isn't creating anything.
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Old 03-03-2013, 03:44 PM   #7073
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Originally Posted by Squidz View Post
The other issue, is that the the later cars run the smaller hole (with the PCV in the plastic piece), as shown in the picture above. My car does not, it's an 03 and runs the PCV in the manifold. I agree that this is a problem for those guys with the smaller hole in the port...how do other systems make this any better?
You dont need the PCV if you have a good and properly working AOS

Quote:
Originally Posted by Squidz View Post
My problem is that people keep blaming the parts. "This part blew up my car"...whatever. It's about understanding what the parts can and can't do. I think it's the case of people using the wrong part, or using the part incorrectly, than an issue with the part itself.
What does this mean? The only incorrect part that I installed was the AOS you seem to think works so well!

Quote:
Originally Posted by Squidz View Post
I think many people overestimate what an AOS can and should do. You put a catch can behind any AOS, you will get stuff in it, as you stated. Yes, even the mighty Crawford (like the one we used on our land-speed car) would fill up our catch can after a while. AOS are designed to reduce the amount of blowby that gets back to the intake, not completely eliminate it. the only way to completely eliminate it is to not return anything to the intake (a.k.a catch can). As far as the AOS creating pressure and hurting things...that could happen with all of them....they all connect the heads to the crankcase vent...and if your crankcase pressure overloads your port, the pressure will go into the heads and get back to the AOS...the pressure would be the same no matter what...so the AOS isn't creating anything.
They are called Air Oil Seperators and if they don't separate the oil from the air that is routed towards the intake, which we use to vent the crankcase then it does not work period!! They have to do this fundamental function to be a working AOS!
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Old 03-03-2013, 04:34 PM   #7074
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Of course you'll get blow by from an AOS. it has a drain that returns warm vapor to the rear baffle.
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Old 03-04-2013, 11:06 AM   #7075
06rexwagon
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Originally Posted by Maxwell Power View Post
Ok so here are some images for you that I scanned out of a book that I like to read and reference when I'm in the learning mood.
The book was written by professors at MIT who had a lot of fun utilizing their engine laboratory and many other resources. This book is THE authority when it comes to learning how engines function.


So, first image is of cylinder pressure with adequate timing with and without knock. If you notice the difference in magnitude of pressures between events and then compare it to the second image that shows an engine that is NOT knocking, but is over timed. You will see that the magnitude of cylinder pressure increase is practically the same. So in both engines, the cylinder pressure is high enough to cause damage.

The second image basically shows what happens when tuners apply too much timing to e85 engines. What you get is blown head gaskets, cracked pistons, spun rod bearings etc. You can also see the effect the timing has on torque output by looking at the graph on the right. That will help you understand what MBT actually is.

Moral of the story: By over timing an engine you can cause just as much harmful cylinder pressures as knock.

If you look even closer, you'll see that the peak pressure in the overtimed engine occur just past TDC, maybe 10*ATDC. In the second engine it occurred at 20ATDC. So if these were the same engines with just different fuels, you would get MORE damage from the knock free over timed engine on high quality fuel than you would get on the knocking engine.

So yeah, I still stand by my comment. It wasn't meant to offend or insult, it was merely just an observation of what probably happened.

Unless you know of some other mystical force other than cylinder pressure that cracks pistons... anyone?
You think that's what could have happened here?
Carrillo Pro H beam rods with under 3k miles on them, E98 fuel, low to mid 600whp uncorrected.
NOT MY CAR, NOT MY TUNE>

Last edited by 06rexwagon; 03-04-2013 at 11:41 AM.
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