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Old 08-19-2013, 01:30 AM   #1
ckyguy68
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Default High Horsepower Crankcase Ventilation

Wanted to get some info together about what BIG HP guys are running for an AOS/Catch can setup. I had a Grimspeed AOS but it wasn't keeping up. I am now temporarily running vents to atmosphere through heater hose and dumping under the car. (all PCV ports)

So if you are 500-700+whp, what kind of PCV setup are you running? I was thinking about going with a Crawford setup but want to be sure it can keep up!

Thanks in advance,

AK
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Old 08-19-2013, 12:10 PM   #2
02WRX2.5
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Crawford wont keep up! You need more capacity and big ports for venting and create good vacuum to drain the can
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Old 08-20-2013, 03:28 PM   #3
ckyguy68
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Quote:
Originally Posted by 02WRX2.5 View Post
Crawford wont keep up! You need more capacity and big ports for venting and create good vacuum to drain the can
your car is trapping over 150. what setup do YOU use?? that is the point of this thread
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Old 08-19-2013, 12:17 PM   #4
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Anyone make a custom one you recommend? Or what are some other options?
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Old 08-22-2013, 11:09 AM   #5
cowboy_Rob
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What's considered the limit for the Crawford? I was planning to buy one but I'm aiming for 500ish whp so I may have to reconsider. Currently just running the stock junk
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Old 08-22-2013, 02:29 PM   #6
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Quote:
Originally Posted by cowboy_Rob View Post
What's considered the limit for the Crawford? I was planning to buy one but I'm aiming for 500ish whp so I may have to reconsider. Currently just running the stock junk
Ask Crawford. I've seen people run dual units, but we're talking extreme setups. I'm at the point you're shooting for and use a single Crawford. It works flawlessly. Seriously, after 10K miles and taking stuff apart there is no more 'film' than on our shop stage II car that runs the same Crawford part. IMO, blowby has more to do with how the engine is built. If you have an engine with sheet loads of blowby it will defiantly overwhelm a crappy design and possibly even a good one.
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Old 08-22-2013, 12:26 PM   #7
02WRX2.5
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I run a custom can I made! -10 drain -vents. I also do my head venting a bit different as well as crank ventilation. Still doing testing before with the venting but seems to be handling it great at 157mph trap speeds so far.
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Old 08-22-2013, 02:50 PM   #8
Scuby04STi
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Have you thought to just go dry-sump?
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Old 08-22-2013, 05:41 PM   #9
KillerBMotorsport
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^ that's a really expensive way to deal with blowby. A good separator will do the trick.
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Old 08-22-2013, 06:12 PM   #10
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Quote:
Originally Posted by KillerBMotorsport View Post
^ that's a really expensive way to deal with blowby. A good separator will do the trick.

I have priced it out, actually not that much more then a high quality pan, pick-up, and pump combination (I have killerbee ;-) ). Then you add a AOS it starts to even out even more. Only reason I did standard pan style set-up was I am very unsure how a dry-sump would like DD situations.

Plus what is cost when you are talking about getting 700+ out of a subi??? This is at least a 100% sure fix.
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Old 08-22-2013, 07:43 PM   #11
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Theres a guy on here named bilyk wrx running an ixiz aos and a 74mm Borg Warner S374. I am pretty sure he was having success using that unit running extreme amounts of boost.

I picked one up for my hta86 E85 setup but the motor finally let go before I got a chance to put it on. I be testing the ixiz unit out once I'm up and running again.
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Old 08-22-2013, 07:50 PM   #12
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I still don't see the point in a dry sump setup to solve a blow by problem, and if there is a blow by problem the dry sump doesn't fix the problem. It will mask it.

Last I looked the mediocre dry sump kits were around $2,500 and a decent setup can add a few a more on top of that.

Besides price you will get no where near multi 100k reliability like you will with an OEM style pump (not that you're necessarily looking for that with a 700+whp Suby).
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Old 08-22-2013, 08:27 PM   #13
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Quote:
Originally Posted by KillerBMotorsport View Post
I still don't see the point in a dry sump setup to solve a blow by problem, and if there is a blow by problem the dry sump doesn't fix the problem. It will mask it.

Last I looked the mediocre dry sump kits were around $2,500 and a decent setup can add a few a more on top of that.

Besides price you will get no where near multi 100k reliability like you will with an OEM style pump (not that you're necessarily looking for that with a 700+whp Suby).
Well, your correct if there is a blow-by issue a dry-sump wont "fix" it, nor with a AOS. They are both products that minimize the negative affects of it (dry-sump. If there is blow-by then its an internal issue that is on another topic then the OP asked about he simply asked about AOS/PCV options, and a dry sump can be rigged to eliminate that system and makes a LOT of sense on a 700+ set-up.

If he asked what should I do to solve blow-by I would say build the motor in a way that the clearance and such are built for his boost level.

Also for dry-sump cost their is not a "kit" I would ever buy, they all have flaws and mark-ups that make it hard to stomach.

But for a straight up AOS I like my Perrin AOS, It has great mounting options and has several options to how you set it up.
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Old 08-22-2013, 09:11 PM   #14
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Quote:
Originally Posted by Scuby04STi View Post
Also for dry-sump cost their is not a "kit" I would ever buy, they all have flaws and mark-ups that make it hard to stomach.
.
I couldn't agree more! Unfortunately, to do it well is still more than a cheaper 'kit'. Although you will get a better bang for the buck going DIY vs paying for the good 'kit'. Still into the few thousand dollar range though. We've done this many times for customers who want to build their own kit, but are lacking the knowledge to build a B.O.M.

I've never seen the Perrin setup until just now. It most definitely resembles the Crawford swirl pot design I really like (cough cough knock-off), but with a few more frills. I don't see it anywhere listed on their website? Pricing?
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Old 08-22-2013, 08:17 PM   #15
fastblueufo
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I run a 2 catch can setup using one on pcv and one on heads. Both are vented to atmosphere via a 3/4" hose to a 2" wire mesh breather. Works great for my setup. If your on a maf system you can vent it back to the turbo inlet as long as the system is working. I modified my pcv can so it would be baffled except I use a thick wire mesh instead of actual baffel walls. Works better than the baffled walls.
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Old 08-22-2013, 09:59 PM   #16
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Quote:
Originally Posted by TDagen View Post
Theres a guy on here named bilyk wrx running an ixiz aos and a 74mm Borg Warner S374. I am pretty sure he was having success using that unit running extreme amounts of boost.

I picked one up for my hta86 E85 setup but the motor finally let go before I got a chance to put it on. I be testing the ixiz unit out once I'm up and running again.
That is what I'm running as well.

Does anyone make better internal baffling? The OEM setup for the crankcase port seems decent but the valve covers just have a run up from the feeding point, I don't think there's any more to it than that. Not to mention the second set of breather lines don't have anything. I can't recall if those two run through the PCV system on the stock setup or just valve cover to valve cover.
Either way, during a high G turn with half your oil supply in one head keeping those breathers err - breathing and not impromptu oil lines might be a better, more preventative approach.


There's also an option of using a pump in place of your pcv valve. This way you'll see -30 psi of vacuum at all times. Route the return line through an AOS - air to the inlet and oil froth to the oil pan.

I don't like sending any metered air out of the system so the VTA option is hogwash to me!
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Old 08-23-2013, 12:14 AM   #17
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Originally Posted by spintheground View Post
Either way, during a high G turn with half your oil supply in one head keeping those breathers err - breathing and not impromptu oil lines might be a better, more preventative approach.
Not to sound too much like captain obvious here, but welcome to the wonderful world of boxer engine design!

People get really hung up in oil coming out of the heads. It's inevitable, don't try to fight it, embrace it, work with it Also, if the head is full of oil, there are no gasses to be vented from that head

If you haven't followed my threads on the subject before, I'm a big fan of swirl pot A/S separators (Crawford) using a vacuum source (turbo inlet) to reduce crankcase pressure and improve A/O separator performance. Alternatives for a vacuum source are a scavenge port in the exhaust or a mechanical pump (scavenge pump).
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Old 08-23-2013, 07:38 AM   #18
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I use the Crawford for my crank case only. Placed a plug on the nipple that normally connects the hose from the heads. Then the heads are teed together and then run directly to the intake manifold. I'm speed density so I only have the 5/8" from the Crawford and 1/2" from the heads connected to my 4" intake.

I'm thinking about putting a catch can on the head line as well. Do the heads have a lot of oil coming out of them? I assumed the majority of oil is from the crank case.
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Old 08-23-2013, 07:53 AM   #19
KillerBMotorsport
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You definitely want something on those lines. I don't recommend a catch can on the heads because they can fill under severe cornering significantly lowering your oil supply.

Why did you not put the heads into the Crawford unit as well?
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Old 08-23-2013, 01:21 PM   #20
Tyrial
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Chris, I'll have to pick your brain about my setup while I'm at your shop next month. I need someone very educated on the subject to sit down with me and answer my "well what if we do this?" questions lol
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Old 08-23-2013, 01:30 PM   #21
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What are your guys thoughts on a setup like is shown at the bottom of this page or the ones using an air pump at the top of the next page. Ignore that the diagrams show a na nissan motor.

Both would use a good aos like the crawford unit but use something other than the intake for the vacuum source.
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Old 08-23-2013, 03:25 PM   #22
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Quote:
Originally Posted by KillerBMotorsport View Post
You definitely want something on those lines. I don't recommend a catch can on the heads because they can fill under severe cornering significantly lowering your oil supply.
Absolutely!! Makes me wonder if that Perrin piece ever went onto the track. The factory plumming almost acts like a self acting check valve for venting the heads.

It is kept in place on my AOS and for good reason. There a few other track oriented techniques that can be implemented to improve ventilation.

-Micah
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Old 08-23-2013, 04:26 PM   #23
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Originally Posted by Homemade WRX View Post

Absolutely!! Makes me wonder if that Perrin piece ever went onto the track. The factory plumming almost acts like a self acting check valve for venting the heads.

It is kept in place on my AOS and for good reason. There a few other track oriented techniques that can be implemented to improve ventilation.

-Micah
3MI Racing
Precision Turbo was saying that oil was being pushed passed the seals due to not enough negative pressure on the crank case. So to alleviate some of the loss suction I wanted to separate the heads from the crank case. So instead of one source of suction at the intake there are two.

So you all are saying I need to re plumb it back on? Maybe put a tee right at the top of the aos line that goes to the intake and connect two hoses to the intake to have more suction that way?
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Old 08-23-2013, 03:32 PM   #24
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on my 35r setup with stock block i vented to atmosphere but had no blow by or drainage at all through the vent tubes. (24 psi)

my first built motor after that was with the 35r and around 24-27 psi pump. I used the crawford aos and never had issues.

Now on my 67mm, have them venting to ground but only temporarily as i noticed they have a little blow by which makes me not happy but this motor is a bit looser than i usually go. i dont like seeing any thing in the vent hoses but i guess it happens :/

OP. i actually have everything to make a few custom cans. do you want to collect the oil or separate and send back?

I really like the crawford aos as when I ran that I never consumed oil at all at least in the 2k oil change ranges.
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Old 08-23-2013, 03:33 PM   #25
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also if you have your valve covers off u could ship them to me or do it yourself-dremel the factory barbs off and weld on fat daddy an fittings to help just a little bit. have to make sure you clean them afterwards obviously before install

Last edited by stretchedk7; 08-23-2013 at 03:34 PM. Reason: spelling! wrong word
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