OCC and crankcase pressure testing diaries

[Matt@DamondMotorsports]

OCC and crankcase pressure testing diaries

Here at Damond Motorsports, I like to test the hell out of my products, to insure their performance, quality, and reliability. This post is about oil catch can kits and crankcase pressures, and the testing I’ve preformed on different Mazdaspeed set-ups.

First off, what is an OCC, and how does it work? An oil catch can/tank/reservoir is a device that captures oil/gases mist caused by blow-by, by putting it in-line of a PCV connection. In turn, the oil/gas gets captured by the OCC, and does not make its way into the intake system. Well, unless you never drain the OCC.

Some OCCs, like the ones I use in my kits, have an internal filter material. This media acts to not only prevent oil from making it back up into the intake system, but helps to condense crankcase oils/gasses mist, so they can drip to the bottom of the OCC.

Crankcase pressure in a high boost application is generally caused by blow-by from the compression chamber. Also, if your rings or cylinder walls are worn, you’ll get more blow-by past the piston, in turn more crankcase pressure. The OEM PCV valve is known to leak a bit, allowing boost to get into the crankcase. High boost applications see higher crankcase pressure, because there is more pressurized air going into the cylinder, which results in more blow-by. This pressure in the crankcase has to be relieved somehow and somewhere, and that is why you commonly see the dip-stick popping out of the tube. The dip-stick is the path of least resistance, however many seals can start to leak with excess crankcase pressure. Oil pan, timing cover, breather cover, oil cooler, valve cover, rear main seal, etc.

Here are some pretty simple paint drawings of all the set-ups tested, how the PCV set-ups flow under different conditions, the results of the vacuum/pressures measured, and my conclusions. Some set-ups were tested on a couple stock turbo MS3’s at 20psi of boost, as well as a BT GTX3071R MS3 at 28psi of boost. Some set-ups were not tested between the stock turbo and BT cars, due to the set-up being not an efficient way to evacuate crankcase pressure on a ST car, so there would be more pressure on a BT car, and time for testing being a factor. For that, I have some estimated readings, according to what data was observed and gathered between the cars tested.

Cars with various intakes were tested as well, to see how much of a vacuum was pulled from the intake. The air rushing through the intake pulls a slight vacuum from the valve cover port, due to the Venturi Effect. Generally, out of the intakes tested, ones were the PCV connection port is closer to the turbo pull a stronger vacuum.

Gauge readings came from various PCV set-up connections.



First let’s look at the OEM set-up:





Under engine vacuum, a vacuum is pulled on the crankcase, from the PCV valve via intake manifold port. The PCV valve is pretty restrictive, but there is enough vacuum in the crankcase, to where it will pull a vacuum from the intake, via the valve cover port.

Under boost, the air rushing through the intake pulls a slight vacuum from the valve cover port, due to the Venturi Effect. Boost going through the manifold is blocked from going into the crankcase via the PCV valve(though some boost can leak in).

Stock turbo:
At engine idle 20-21in/Hg: 1 to 3in/Hg
At full boost WOT 20psi: 2 to 4psi(depending on intake)
Big turbo: ESTIMATED
At engine idle 20-21in/Hg: 1 to 3in/Hg
At full boost WOT 28psi: 3 to 5psi(depending on intake)

Conclusions: This works well for most stock cars running at stock boost levels. There will still be blow-by and oils will enter the intake system, without an OCC in place. Under high boost applications, boost can seep past the PCV valve into the crankcase, leading to higher pressure.




Here’s the OCC set-up I use for my kits:





Under vacuum and boost, the conditions are the same as OEM, though the check valve included in my kits is in place to prevent boost from entering the crankcase, via the prone to leaking OEM PCV valve.

Stock turbo:
At engine idle 20-21in/Hg: 1 to 3in/Hg
At full boost WOT 20psi: 1 to 3psi(depending on intake)
Big turbo:
At engine idle 20-21in/Hg: 1 to 3in/Hg
At full boost WOT 28psi: 2 to 3psi

Conclusions: This set-up works well, mainly on stock turbo cars. For higher boost cars, there is a bit of pressure in the crankcase, since it can only be evacuated via the VC breather port into the intake. There is a vacuum on the crankcase, under most conditions, though under full boost there can be excess pressures.




Here’s an OCC set-up, where both PCV ports are routed to the OCC, and the system relies only on intake Venturi vacuum, as the vacuum source:






Stock turbo:
At engine idle 20-21in/Hg: 0 to .5psi(depending on intake)
At full boost WOT 20psi: 1 to 3psi(depending on intake)
Big turbo: ESTIMATED
At engine idle 20-21in/Hg: 0 to .5psi(depending on intake)
At full boost WOT 28psi: 2 to 4psi(depending on intake)

Conclusions: I was quite surprised to see this set-up works fairly decently. It omits a CV, since one is not needed. Under engine vacuum, there is a slight pressure on the crankcase, though it’s so low, it’s hard to read or feel. Under stock turbo boost the intake does a good job at evacuating most pressures, via the vacuum being pulled from the intake. On a BT car, I estimate the PCV valve becoming a restriction. The main thing I don’t like about this set-up, is that the crankcase is always under pressure, even though it’s very minimal at idle, it’s still pressurized. So under most engine driving conditions(engine vacuum… unless racecar), there’s always a slight pressure in the crankcase.




Here’s a total VTA set-up, where both PCV ports are connected to a VTA OCC, no vacuum is used to evacuate crankcase pressures.






Stock turbo:
At engine idle 20-21in/Hg: 0 to 1psi
At full boost WOT 20psi: 2 to 3psi
Big turbo:
At engine idle 20-21in/Hg: 0 to 1psi
At full boost WOT 28psi: 3 to 4psi

Conclusions: the fully VTA set-up has a lot of restrictions to overcome, in order to relieve crankcase pressure. Under boost, the blow-by pressurizes the crankcase, since the pressure has to come out of the restrictive PCV valve, or all the way up to the valve cover breather port. The pressure escapes mostly via the VC port, due to it being the path of least resistance. If the PCV valve were to be “ported” where it’s guts were removed, the pressures would be a bit lower. With a full VTA set-up the crankcase is always under pressure, even at idle where my gauges read zero, you can feel very slight air pressure coming out of the OCC vented port or the dipstick tube(with the dipstick removed).




Here is the set-up we found to work best on both the stock and big turbo MS3’s. It uses my current kit set-up with an additional check valve in-line that VTA’s under pressure.





Stock turbo:
At engine idle 20-21in/Hg: 1 to 3in/Hg
At full boost WOT 20psi: .5 to 1psi(depending on intake)
Big turbo:
At engine idle 20-21in/Hg: 1 to 3in/Hg
At full boost WOT 28psi: .5 to 1psi

Conclusions: this set-up worked the best to evacuate extra pressures on both the ST and BT cars. The slight pressures seen are due to the cracking pressure of the VTA CV and the PCV valve being a restriction. The intake is still in place to pull a vacuum and help to keep pressures down. I believe this to be the best way to relieve excess crankcase pressures on speeds up to 30psi of boost.


I will have add-ons soon to include a VTA CV with my kits(different CVs are being tested at the moment). I will also be able to supply all prior customers with these components, for very little money, so you can add this to your current set-up, if you deem necessary. For potential customers, I am working on an OCC with an incorporated VTA CV, to relieve excess crankcase pressure.











Beyond 30psi of boost, I have a couple set-ups in mind using Dustin’s PCV plate, or similar, as well as an additional vented OCC. This way, there is an additional port on the breather box, with no PCV valve restriction to overcome, during times where there would be excess crankcase pressure. I'll diagram the set-ups I'll be testing for this soon.

Any questions, comments, concerns, please post up.



@djuosnteisn
@burn813
@silvapain
@atvfreek
@phate
@Alpha
@JLee1469
others I forgot to mention

[Alpha]

Awesome testing man! Looking forward to rockin your stuff with my PERM plate!

Once, my car doesn't overheat, of course lol

[mike w]

Awesome info! Thanks.

[Alpha]

Bump for this!

[IamJamen]

I was planning on doing some similar testing but you beat me to it. Thanks for saving me from all that work.

[alphasaur]

I need a catch can, god speed.

[breakfstincluded]

take my money!

[Etipp98]

Good deal! I am testing some stuff out right now as well!

[Matt@DamondMotorsports]

Originally Posted by Etipp98 Good deal! I am testing some stuff out right now as well!

Awesome dude, feel free to post up in here what you test. I'd be glad to see the results of someone else testing pressures/vacuum.

Now that I have a MS6, I'm going to do some more crankcase testing soon... with more gauges at different locations on the crankcase.

Originally Posted by helmetface Awesome diagrams Matt, really helps put this into perspective. For the record, while I was commanding anywhere from 22 to 26psi on the gtx3071- I was running your standard single can setup pcv > occ > cv > im - with a breather on the vc. I had zero issues running this way, I know some people would experience a decent amount of oil spitting out their vc vent- however this was not the case with me. The occ still filled regularly and vacuum levels were to be expected.

I was going to test the set-up where there's a standard OCC on the mani-pcv valve side, with a filter on the VC breather. However, you have to tune the car for un-metered air flow, and under boost/pressure, it has to travel all the way up to the VC to vent. I like the idea of the intake, or and exhaust venturi slash cut, providing vacuum under boost conditions, with a CV to VTA when there is pressure. Also, I've heard back from customers that have had issues with excessive blow-by oil out of the VC with the vent, as well as dip-stick popping issues.

Originally Posted by Dano FWIW...your MS Paint depictions are much better than the ones from that other guy

hahaha, I was gonna draw everything up in SolidWorks, but that would take me like a day, since I'm not as proficient at SW as I used to be... so I did this all in paint in like 30min.

Plus, drawing in paint is soooo much more fun.

[djuosnteisn]

Originally Posted by Dano FWIW...your MS Paint depictions are much better than the ones from that other guy

Not sure if i'm that "other guy" or not, lol. But i did spend a bit more time with the drawings on the perm site's PCV tech article.

Matt, very good write up and analysis. The TIP vacuum at wot definitely seems to have quite an effect. I bet there's typically 1-2 psi of vacuum at that point (depending on how dirty or restrictive the air filter is)... which is definitely in line with what your data shows.

I still need to send you plate for testing. I'll do that this week.

Thanks for taking the time to do some thorough testing. It's obvious when a manufacturer has a solid understanding of the system he's making parts for. Kudos to you

[Dano]

what?...um...no...not you

but seriously I was just hacking on ya...I like both of your MS Paint depictions.

[helmetface]

Awesome diagrams Matt, really helps put this into perspective.

For the record, while I was commanding anywhere from 22 to 26psi on the gtx3071- I was running your standard single can setup pcv > occ > cv > im - with a breather on the vc. I had zero issues running this way, I know some people would experience a decent amount of oil spitting out their vc vent- however this was not the case with me.

The occ still filled regularly and vacuum levels were to be expected.

[Dano]

FWIW...your MS Paint depictions are much better than the ones from that other guy

[burn813]

Matt, immma let you finish but Dustin had the ms-paint ever

[atvfreek]

I was originally running your option1 until I cranked boost up to 27psi seeing what this bnr was made of, when my dipstick decided it would rather hang out in my hood scoop and spray oil everywhere. Lol. (Actually wasn't that funny because it sucked to clean up)

At that time I decided I would try option 2, in which cs runs a similar method. That worked great at keeping my dipstick at bay, but I started to get an oil leak at my turbo oil return line. Seems these cars definitely like vacuum on the cc whenever possible to help with oil control issues.

So on a mission I tried option3 (mind you I've been messing with this since before Xmas). This is what I came up with to run inline with the hose to the IM from the occ
uploadfromtaptalk1364431270114.jpg

I had it long enough so that when cc vapor would escape through my little filter it would sort of get sucked in through my air filter and keep the odor at a minimum. Here is the installed pic
uploadfromtaptalk1364431360574.jpg
uploadfromtaptalk1364431406000.jpg

I ran that setup with great success for a couple months. However I wanted to add an occ inline with my vc port. When thinking of a plan, I decided it would be best to run a traditional can like option 1, then add a second vc port to allow additional vapor to find its way out of my cc with ease. So I ordered this from matt. It's a dual occ setup and I now run a fully closed system. This has been working flawlessly with my 2 vc ports going to one can and routed back to the tip. Then the other can is setup like option 1. No dipstick flying out, no odor after hard wot runs, no oil leaks. Happy car!!!
uploadfromtaptalk1364431569569.jpg

Sent from your couch

[KevinK2]

Originally Posted by atvfreek I was originally running your option1 until I cranked boost up to 27psi seeing what this bnr was made of, when my dipstick decided it would rather hang out in my hood scoop and spray oil everywhere. Lol. (Actually wasn't that funny because it sucked to clean up) At that time I decided I would try option 2, in which cs runs a similar method. That worked great at keeping my dipstick at bay, but I started to get an oil leak at my turbo oil return line. Seems these cars definitely like vacuum on the cc whenever possible to help with oil control issues. So on a mission I tried option3 (mind you I've been messing with this since before Xmas). This is what I came up with to run inline with the hose to the IM from the occ I had it long enough so that when cc vapor would escape through my little filter it would sort of get sucked in through my air filter and keep the odor at a minimum. I ran that setup with great success for a couple months. However I wanted to add an occ inline with my vc port. When thinking of a plan, I decided it would be best to run a traditional can like option 1, then add a second vc port to allow additional vapor to find its way out of my cc with ease. So I ordered this from matt. It's a dual occ setup and I now run a fully closed system. This has been working flawlessly with my 2 vc ports going to one can and routed back to the tip. Then the other can is setup like option 1. No dipstick flying out, no odor after hard wot runs, no oil leaks. Happy car!!!

How much oil/krap from the two VC vents get caught in the OCC, that exits to the TIP ?

.

[KevinK2]

Originally Posted by atvfreek I was originally running your option1 until I cranked boost up to 27psi seeing what this bnr was made of, when my dipstick decided it would rather hang out in my hood scoop and spray oil everywhere. Lol. (Actually wasn't that funny because it sucked to clean up) At that time I decided I would try option 2, in which cs runs a similar method. That worked great at keeping my dipstick at bay, but I started to get an oil leak at my turbo oil return line. Seems these cars definitely like vacuum on the cc whenever possible to help with oil control issues. So on a mission I tried option3 (mind you I've been messing with this since before Xmas). This is what I came up with to run inline with the hose to the IM from the occ I had it long enough so that when cc vapor would escape through my little filter it would sort of get sucked in through my air filter and keep the odor at a minimum. Here is the installed pic I ran that setup with great success for a couple months. However I wanted to add an occ inline with my vc port. When thinking of a plan, I decided it would be best to run a traditional can like option 1, then add a second vc port to allow additional vapor to find its way out of my cc with ease. So I ordered this from matt. It's a dual occ setup and I now run a fully closed system. This has been working flawlessly with my 2 vc ports going to one can and routed back to the tip. Then the other can is setup like option 1. No dipstick flying out, no odor after hard wot runs, no oil leaks. Happy car!!!

ATVfreek has a great closed set-up. I think the extra can for the CC vent, and an added cc vent path to this can and on to the TIP allows low cc pressure at high boost. He used the vc for adding a 2nd cc port, but a line off the PCV valve box should also work (like Tokay444?).

For the extra new cc/vc port, it should have some baffeling to reduce the liquid flow.


.

[802MS3]

@atvfreek; pics of valve cover please!

and this wouldn't be MSF without paint drawings

[atvfreek]

Originally Posted by 802MS3 @atvfreek; pics of valve cover please! and this wouldn't be MSF without paint drawings

I suck at ms paint. Lol. But I will grab a new pic tomorrow sir.

Sent from your couch

[atvfreek]

Originally Posted by 802MS3 @atvfreek; pics of valve cover please! and this wouldn't be MSF without paint drawings

Here is a pic of the engine bay. You can see the additional port and braided hose going over the hotpipe
uploadfromtaptalk1364493222259.jpg

Sent from your couch

[Andjo]

I went vta on the valve cover and plug the hole in the intake. Been looking for a good cc to vent the crankcase that doesn't cost $300 like the SSP one. Hope you get this worked out.

[superskaterxes]

any interest in testing a mechanical vacuum pump?

[Alpha]

Originally Posted by superskaterxes any interest in testing a mechanical vacuum pump?

▲ Racecar shit! Ha

[djuosnteisn]

Originally Posted by atvfreek Here is a pic of the engine bay. You can see the additional port and braided hose going over the hotpipe Sent from your couch

If your hot pipe coupler blows off, it'll take that line with it. You should probably route it under the hot pipe.

Engine bay looks good though

[Matt@DamondMotorsports]

Originally Posted by atvfreek I ran that setup with great success for a couple months. However I wanted to add an occ inline with my vc port. When thinking of a plan, I decided it would be best to run a traditional can like option 1, then add a second vc port to allow additional vapor to find its way out of my cc with ease. So I ordered this from matt. It's a dual occ setup and I now run a fully closed system. This has been working flawlessly with my 2 vc ports going to one can and routed back to the tip. Then the other can is setup like option 1. No dipstick flying out, no odor after hard wot runs, no oil leaks. Happy car!!!

Awesome to see what you did with that dual OCC Justin. I've tested a few closed loop systems with the dual OCCs before, but mainly with the stock ports. @Ckmazdaspeed3 ; is running a dual set-up with an extra port on the breather box. IIRC he hasn't really captured much oil with the second OCC, but the hoses are routed to where it will more than likely drain back to the breather box.

Originally Posted by Andjo I went vta on the valve cover and plug the hole in the intake. Been looking for a good cc to vent the crankcase that doesn't cost $300 like the SSP one. Hope you get this worked out.

Yeah, I'm working on a whole new designed OCC that will incorporate a VTA checkvalve. I'm also pretty set on the components I want to use for existing customers kits, so they can adapt the new set-up. For people running really high boost set-ups, I think the best route is going to be adding an additional port, for a less restrictive flowing system. Like what atvfreak did with his VC, or with Dustin's plate.

Originally Posted by superskaterxes any interest in testing a mechanical vacuum pump?

Possibly, I've looked into a couple electrical vac pumps in the past. Are you thinking of a belt driven pump or electrical pump?

[seshomaru7]

What about this? The crankcase and valve cover breather hose...teed into the OCC, then a check valve for the manifold vacuum source teed into the TIP vacuum? I could see that this may pull air from the TIP through the hose to the manifold if the manifold vacuum is greater than the vacuum in the TIP. Could another check valve be added to not allow backflow of air from the TIP back to the OCC then? Or am I just making this more complicated than it has to be?

[rdguindon]

just came across this article and wanted to say thanks for the info

im a little confused about what your numbers mean:
"At engine idle 20-21in/Hg: 1 to 3in/Hg"
is the first number the vacuum at the PCV valve, and the second number the pressure in the crank case?

Also how are your OCC's put together? Are the top, bottom, ports welded or glued onto the can? What type of filter media do you use.
thanks

[Matt@DamondMotorsports]

Originally Posted by rdguindon just came across this article and wanted to say thanks for the info im a little confused about what your numbers mean: "At engine idle 20-21in/Hg: 1 to 3in/Hg" is the first number the vacuum at the PCV valve, and the second number the pressure in the crank case? Also how are your OCC's put together? Are the top, bottom, ports welded or glued onto the can? What type of filter media do you use. thanks

The first number is the vacuum reading from the manifold at idle, so basically prior to the PCV valve. The second is vacuum at the crankcase, past the PCV valve.

The Saikou Michi OCCs I use in the kits are of a complete welded aluminum structure, with baffling in the top portion and inlet tube of the can. The baffling is a 3 layer mesh, I believe made of stainless steel, it could be aluminum though.

[KevinK2]

Originally Posted by Damond Motorsports The first number is the vacuum reading from the manifold at idle, so basically prior to the PCV valve. The second is vacuum at the crankcase, past the PCV valve.....

Nice work Matt. I've done similar testing on the Rx7 that I tracked. I used a Dwyer differential pressure gauge to check the intake for pressure drops. After porting the IC inlet, and mofifying the air filter box inlet, I could run at max boost and not see any vacuum in the inlet pipe/tube, where the hose to the "VC" connected.

Have you done any intake measurments to see if there really is a vacuum? With most MS3's and MS6's in this crowd having CAI's and open filters, I thought it would be unlikely for an intake vacuum to exist to help pull out crankcase vapors.



.

[mazdafreak]

Im running MD dual occ setup....Works flawless! One sealed and one vented!

[hgunther]

So, JBR do you recommend doing a combination of your listed above best option and perms recommended one with the PVC plate?

[phate]

This isn't JBR. This is Damond Motorsports, the original!!

Edit: IT'S 2014!!!!!!!!!!!!!!!11

[hgunther]

My bad!!! I meant no disrespect!!! I was reading two threads at once and not thinking while typing. What is your recommendation for BT occ setups. My precision 6266 will be pushing 45 psi when I'm done.

[btstarcher]

According to the original post, he measured between 1 and 3 in/Hg at idle and 2 to 4 psi at full boost with the stock K04. Big turbo he estimated between 3 and 5 psi at full boost. I don't know if I agree; most big turbo cars also have a larger diameter intake setup, thereby reducing the velocity of the air. So less Venturi effect.

[KevinK2]

Those measurements represent the crankcase pressure, measured where the PCV valve is fitted. I guess his guess is just a guess .....


I am interested if Matt measured any significant vacuum in the intake pipe/tube.

A ventury effect calls for a necking down of a bore to increase local velocity and decrease pressure. This intake connection simply relies on a pressure drop caused by a restriction at points upstream of the flow, like at the MAF or filter & Housing. Adding a big intake and MAF sensor could eliminate this vacuum.

.

[Tokay444]

put the outlet of the vent right at the compressor housing.
as boost increases, so will vacuum on that vent.

[KevinK2]

deleted

[KevinK2]

deleted

[btstarcher]

I was under the impression that he actually took measurements at the VC; however after reading it again I can see your point. Clarification please @MATT DAMOND; or @Damond Motorsports;

[Tokay444]

i never mentioned that port anywhere in anything i've posted.

you can't read, and I'M the one with no technical spheres.