AOS Choices for Harrop SC

[M0nk3y]

To expound, I currently have a Verus AOS installed on my built motor (IAG 600, GSC Intake/Exhaust Valves, GSC Springs, Killer B Pickup, Moroso Baffle)

First track weekend, I’m getting significant oil coming I into my intake box. I’m capturing some within my AOS, but there either is a saturation point with my exceeding the capacity of the AOS or it’s mesh isn’t enough to handle the flow going through it.

Dumping it every session, but I’m still discovering oil. Here’s what’s coming out of the AOS




This is what my intake box looked like (granted I didn’t dump my AOS until after the 3rd session when I started to see oil seeping from the intake box



Anyone having issues like I am with this much blow by?


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[ybotspawn]

Do you have the drain back for the verus installed? I had this problem with my radium’s and actually went to verus w drain back. Out of curiosity, how are your oil temps?


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[M0nk3y]

Originally Posted by ybotspawn

Do you have the drain back for the verus installed? I had this problem with my radium’s and actually went to verus w drain back. Out of curiosity, how are your oil temps?


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I had the drain back installed, and either I didn’t have it tighten down or something and early on when we assembled the engine and somehow disappeared from my engine bay. Still kind of miffed about that one…

So currently, it’s capped. I am curious if that would be the simple fix. And/or if blowby is still going to occur. The first session on Sunday I had an empty AOS, didn’t capture much and seemed to still get some oil into the intake (but truly unsure if it was residual being a PITA or whatever).

Temps were 230F peak (I think I saw a blip up to 235F) in Alabama heat. JR Dual Rad/Oil cooler, Verus Hood Vents and Ace Radiator Shroud. From temp perspective the car was awesome.

I have some concerns about my oil pressure, but that’s a whole other topic… (seeing 40 psi at WOT with 20w50 at 230F, 65 psi at 200F and 52 psi at 220F at 4k in paddock)


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[ybotspawn]

I’ll definitely defer to people on here smarter than I but those pressures with that oil seem off. I was asking about temperatures (and indirectly pressure) out of curiosity if they were related to the blow by issue. Really curious what some of the vendors and more experienced folks have to say about this issue.

Good luck


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[M0nk3y]

Also, one more observation.

The Harrop Kit utilizes the stock PCV Valve. I noticed JR has an upgraded PCV valve to prevent blow by.

Don’t know if that’s the smoking gun here, but probably doesn’t hurt


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[ybotspawn]

Originally Posted by M0nk3y

Also, one more observation.

The Harrop Kit utilizes the stock PCV Valve. I noticed JR has an upgraded PCV valve to prevent blow by.

Don’t know if that’s the smoking gun here, but probably doesn’t hurt


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Good point, I replaced that on mine as well with in think one from a wrx….


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[Mike_ZN6]

I think this thread has some applicable information: https://www.ft86club.com/forums/showthread.php?t=139784

[Irace86.2.0]

Originally Posted by M0nk3y

Also, one more observation.

The Harrop Kit utilizes the stock PCV Valve. I noticed JR has an upgraded PCV valve to prevent blow by.

Don’t know if that’s the smoking gun here, but probably doesn’t hurt


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That shouldn't matter, but I changed it too, if I remember correctly, after I was told it was not necessary. The PCV valve on the Harrop SC comes from a vacuum source on the front of the blower. It is pre-SC, so it never sees positive pressure, which, as I understand it, is the whole point of switching to a WRX PCV.

If blowby is coming from the front vent to the air inbox and then getting sucked back into the supercharger then I would consider filling the AOS with steel wool or something else to capture more of the blowby. If that doesn't work then consider venting to atmosphere or getting a much larger AOS.

[M0nk3y]

Originally Posted by Irace86.2.0

That shouldn't matter, but I changed it too, if I remember correctly, after I was told it was not necessary. The PCV valve on the Harrop SC comes from a vacuum source on the front of the blower. It is pre-SC, so it never sees positive pressure, which, as I understand it, is the whole point of switching to a WRX PCV.

If blowby is coming from the front vent to the air inbox and then getting sucked back into the supercharger then I would consider filling the AOS with steel wool or something else to capture more of the blowby. If that doesn't work then consider venting to atmosphere or getting a much larger AOS.

Yeah, that was my understanding thinking more into it - that it doesn't positively pressurize.

I'm going to take apart the AOS and re-pack it. It already has steel material within it, no clue if that's a serviceable item or not. But based on where the oil is coming from/ending up, it's not on the SC side of things....at least not how I think it

[Irace86.2.0]

Originally Posted by M0nk3y

Yeah, that was my understanding thinking more into it - that it doesn't positively pressurize.

I'm going to take apart the AOS and re-pack it. It already has steel material within it, no clue if that's a serviceable item or not. But based on where the oil is coming from/ending up, it's not on the SC side of things....at least not how I think it

After looking back through the posts, I would say this AOS is a very low capacity AOS for FI track use. Unless you have some hoses crossed in an odd way, I would say that your likely problem is the AOS itself, and your immediate fix is to get the drain kit installed. Note in the video below at 25:30, he says he needs to upgrade to a 2L catch can to comply with racing rules in the class he will be entering. Two liters!

I don't know what the ring gap is on an AIG motor, but I would imagine it might be a little greater than OEM to accommodate racing and FI, so you might see more blowby than with a stock engine, but the big difference in blowby comes from FI and WOT for sustained periods, and what you want is a large capacity AOS for a few reasons. Part of the reasons for -10AN hose sizes and a large catch can is the air slows down as it leaves the engine. The larger the hose and can, the slower the air, which gives the catch can more time to extract gas/oil, while also providing the volume to store the oil. The design of the Verus AOS isn't bad, but the pressure and speed of the air through the AOS might be significantly higher than a larger AOS with larger lines. Your AOS is likely filling up and just purging out into your air intake from the force and speed of the air. There might be a Venturi effect in the speed of the air, and a siphoning or pressure effect to empty the AOS once it does fill. Again, adding the drain hose will add some capacity in the hose and help to drain the system. Of course, make sure the direction of the check valve on the drain is going the right direction.

[Grady]

Ok first thing is there is a difference between AOS and catch can. An AOS separates the oil and air and returns the oil to the engine. A catch can catches the oil for draining later. I agree with Irace the Verus when plumbed as a catch can is to small. As an AOS I think it is destined good. NA and low boost will work well on an AOS and you can still have crankcase ventilation. For high boost you will need to go with a catch can and eliminate PCV.