OCC and crankcase pressure testing diaries

[Tokay444]

I don't have an extra vc vent. Just a perm plate with the second port T'd into the vc vent then can then tip.

[KevinK2]

On the subject of vacuum in the intake, I checked the vacuum based on stagnent air (no ram velocity) entering a 3" dia intake.

Assumed 29 psi boost, .85 VE, 390 CFM into intake, and no pressure drop at filter or MAF.

The vacuum was .135 psi, or .27 " HG. Very low. Unless those pressure drops are high, the CC does more pushing than the intake pulls at the TIP.

dP =.5 x p/g x V^2

dP = pressure drop, PSF (converted to psi)
p = air density, PCF
g = constant, 32.2 ft/sec^2
V = air velocity in intake, ft/sec


As I posted before, and others concur, close to the compressor inlet, there is a transition from the small opening in the casting to the larger bore of the inlet pipe. There the vacuum will be stronger.

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[Tokay444]

I know.

[Matt@DamondMotorsports]

Originally Posted by KevinK2 Thanks for the reply Damond. Correct me if I'm wrong, but I thought you were the first to make and sell manual boost controlers back in the 90's ? Here it sounds like the closer to the compressor inlet, the more the influence of the relatively small inducer dia, relative to the larger funnel section where the inlet coupling hose attaches. So there is some higher velocity flow in this transition, that would drop the ambient air to a vacuum. Do you remember what the highest vacuum readings were? Regarding vc and cc pressures, would they be the same, due to the volumes being connected at the timing chain location? Lastly, rather than adding an extra vented line to the pcv box, add it to the VC that combines with the oem vc line, and to another CC then to the TIP. This would allow a closed system with high boost and low cc pressure. Similar to atvfreek's set-up

I never made boost controllers in the 90's. I was, at the most, 11yrs old at certain points of the 90's.

On the two stock turbo intakes I tested, a cobb vs a CS, the cobb pulled around 1-3in/HG, and the CS pulled 4-6in/HG, at full gallop. The cobb has the PCV port right behind the MAF, similar to the OEM mazda intake port. The CS on the other hand, has the PCV port on the inlet pipe, much closer to the turbo.

On the BT car tested with a 3.5" HTP full intake, it was 4-6in/HG, since the PCV port is closer to the turbo, like the CS one. The turbo on this car was either a GT30 or 35, so it'll move more air, hence why the reading was similar on a bigger dia intake.

I'm not 100% sure that CC and VC pressure would be the same, as all of that air has to travel via the oil galleys in the head and timing cover. I've mainly measure pressure at the VC, but I will be adding a port on mah modified breather box, to see if there is a variance is CC pressure vs VC pressure. I doubt it though.

I have thought about testing the VTA add-in set up at the VC as well, to see if the PCV valve is too much of a restriction. However, there is generally a vacuum present in that connection, under conditions where CC pressure is common. If that is the case, the valve won't really open.

Originally Posted by CosmicArkie Matt, Have you gotten a chance to put together the retrofit VTA kits yet? Do you have a feel for the actual volume of air being moved from the VC to the TIP in the case of the stock/sealed system? TIA

I am going to try and finish it up, once I can get more testing done on that set-up. I should be putting the added VTA set-up on my car tomorrow, and capping the VTA valve on the modified breather box, so I can determine if the PCV valve is going to be a restriction.

The new check valve I will be using for a "retrofit VTA kit" has basically no cracking pressure, so it should be able to vent crankcase pressures super easily as long as it can overcome the PCV valve restriction VS how much pressure is in the crankcase.

[KevinK2]

Originally Posted by Damond Motorsports ..... I have thought about testing the VTA add-in set up at the VC as well, to see if the PCV valve is too much of a restriction. However, there is generally a vacuum present in that connection, under conditions where CC pressure is common. If that is the case, the valve won't really open ..... ..... I am going to try and finish it up, once I can get more testing done on that set-up. I should be putting the added VTA set-up on my car tomorrow, and capping the VTA valve on the modified breather box, so I can determine if the PCV valve is going to be a restriction. The new check valve I will be using for a "retrofit VTA kit" has basically no cracking pressure, so it should be able to vent crankcase pressures super easily as long as it can overcome the PCV valve restriction VS how much pressure is in the crankcase.

Originally Posted by Matt's Prior Post However, I did not like the fact for pressure to VTA from the crankcase, it would have to overcome the restriction of the PCV valve. So I've simplified that a little with modifying my PCV box to accept a check valve that will VTA pressure at the crankcase, and only have to overcome the cracking pressure of the check valve.

I'm confused, I thought the kit would be parallel to the pcv valve path that's illustrated?

Also, based on some one-way pcv valves that I tested, the restriction is variable. When you have high vacuum in the IM, the flow area is small. But installed per the illustration, the pressure drop across the valve is much smaller, and the opening in it is relatively big for cc venting purposes. Is that still too restrictive?


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[Matt@DamondMotorsports]

Originally Posted by KevinK2 I'm confused, I thought the kit would be parallel to the pcv valve path that's illustrated? Also, based on some one-way pcv valves that I tested, the restriction is variable. When you have high vacuum in the IM, the flow area is small. But installed per the illustration, the pressure drop across the valve is much smaller, and the opening in it is relatively big for cc venting purposes. Is that still too restrictive?

If further testing deems it beneficial, then yes. The part you have highlighted of my quote was me saying MY set-up(with the VTA valve on the breather box). Something else that I will test more in-depth, and possibly offer, if beneficial.

I did measure the flow of vacuum pulled after an OEM DISI PCV valve, at different vacuums, a long long long time ago, and the PCV valve was a large restriction. But it needs to be, so you don't pull too much of a vacuum on the crankcase. Though the opening of the valve may seem large, the innards are quite small, and don't allow for much of an opening.

[mtosofsky]

@Damond Motorsports;

Matt, say we wanted to run the modded stock pcv box like what you posted on page 2 (check valve attached to new port on box). If we utilize a very low pressure cracking CV, whats to keep that valve from opening up really really easily (i guess thats saying we have bad crank case pressure) and spraying any potential blow-by out of that CV rather than running through the seal catch can that i have utilizing the standard occ layout. I guess im saying whats to stop the blow by from taking the path of least resistance and making a mess. Maybe we'd have to throw a vented occ onto that line?

[Matt@DamondMotorsports]

Originally Posted by mtosofsky @Damond Motorsports; Matt, say we wanted to run the modded stock pcv box like what you posted on page 2 (check valve attached to new port on box). If we utilize a very low pressure cracking CV, whats to keep that valve from opening up really really easily (i guess thats saying we have bad crank case pressure) and spraying any potential blow-by out of that CV rather than running through the seal catch can that i have utilizing the standard occ layout. I guess im saying whats to stop the blow by from taking the path of least resistance and making a mess. Maybe we'd have to throw a vented occ onto that line?

Well, the VTA valve will pretty much remain closed, as long as there is a vacuum on the crankcase, which there is under engine vacuum conditions, like what travels through the sealed OCC set-up.

The times the VTA valve will open are when there is pressure inside the crankcase. Generally there is little to no pressure, where there is a vacuum present in the manifold. When the sealed OCC set-up sees boost, the CV in the sealed set-up will close. If there is pressure in the crankcase, surpassing the vacuum pulled from the intake via the valve cover, it will go the path of least resistance, via the VTA valve.

However, the PCV breather box and the engine block, have a slight amount of baffling in them, basically plates the oily air has to travel around, which allows the oil vapours to collect, and not make their way out of the VTA valve, leaving an oily mess everywhere.

You could throw a vented OCC onto the VTA valve, if there were to be copious amounts of blow-by coming out of the valve. However, there really isn't enough crankcase pressure being made on the stock turbo, to release blow by oil everywhere. I'm sure on a BT car, adding a VTA OCC would be beneficial to collecting the oily blow-by coming out of the valve.

I have a tiny filter on my VTA valve, and it has collected a little bit of oil, but not enough to leave traces of oil or make a mess anywhere on the front of my engine.

[KevinK2]

Based on his response to my questions, the kit he spoke about adds a "T" to the basic set-up like yours, with a new check valve to a VTA filter. This extra line is so when boosting, the pcv valve can vent cc pressure through the VTA and filter. He supplies an extra cv at the manifold port to prevent boosted air from going through the new VTA he added.

There is no extra hole in the PCV valve box.

As he told me, adding a new vent from the block or the VC is another option he is currently testing.


Note, This slow, distracted poster finished this post before I saw Matt's new reply.
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[KevinK2]

Originally Posted by Damond Motorsports ... I did measure the flow of vacuum pulled after an OEM DISI PCV valve, at different vacuums, a long long long time ago, and the PCV valve was a large restriction. But it needs to be, so you don't pull too much of a vacuum on the crankcase. Though the opening of the valve may seem large, the innards are quite small, and don't allow for much of an opening.

One other reason for the PCV valve opening to be small at high manifold vacuum, is to be able to regulate the idle. The flow at the valve must be small.


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[crutch77]

Originally Posted by Damond Motorsports OCC and crankcase pressure testing diaries 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.

Any update on the kits? I'm looking to modify my existing sealed OCC setup so it will VTA under boost. Tired of my dipstick popping out I've been playing with different options, but if you've got a kit ready to go I'd love to try it out.

[5LOWMS6]

Originally Posted by Damond Motorsports On the two stock turbo intakes I tested, a cobb vs a CS, the cobb pulled around 1-3in/HG, and the CS pulled 4-6in/HG, at full gallop. The cobb has the PCV port right behind the MAF, similar to the OEM mazda intake port. The CS on the other hand, has the PCV port on the inlet pipe, much closer to the turbo. I'm not 100% sure that CC and VC pressure would be the same, as all of that air has to travel via the oil galleys in the head and timing cover. I've mainly measure pressure at the VC, but I will be adding a port on mah modified breather box, to see if there is a variance is CC pressure vs VC pressure. I doubt it though.

I'm going to switch my cobb TIP for the CS one to see if my can will collect more than it has been collecting lately.. picture shows how much it collected in around 1000kms

PCV>OCC>Cobb Intake Port, VC>VTA

[btstarcher]

Why would that have anything to do with how much your OCC collects?

[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.


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[5LOWMS6]

Originally Posted by btstarcher Why would that have anything to do with how much your OCC collects?

I think my current setup isn't providing enough vacuum.

[btstarcher]

There's not much vacuum there anyway. The only thing that would make a difference would be a better flowing turbo or a narrower diameter intake. But the narrower diameter intake is counterproductive to higher HP.

[KevinK2]

Originally Posted by 5LOWMS6 I'm going to switch my cobb TIP for the CS one to see if my can will collect more than it has been collecting lately.. picture shows how much it collected in around 1000kms PCV>OCC>Cobb Intake Port, VC>VTA

You don't get much oil in that can, since the intake manifold vacuum is much greater than a TIP port, and you pluged the IM port. As Matt said, the PCV valve has a lot of flow resistance.


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[KevinK2]

Originally Posted by btstarcher There's not much vacuum there anyway. The only thing that would make a difference would be a better flowing turbo or a narrower diameter intake. But the narrower diameter intake is counterproductive to higher HP.

On page 1, Matt showed his vacuum measurments, and noted the TIP vacuum was greater close to the turbo vs the other locations. I suspect it's due to a velocity increase as the air enters the smaller opening at the compressor inlet. That would suggest a smaller dia intake would not get as much vacuum kick near the inlet.



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[5LOWMS6]

@Damond Motorsports; would it be possible for you to test a 3" HTP inlet on a k04 to see how much vacuum it pulls since the port is very close to the turbo just like the CS TIP ? Thanks.

[redboat]

Matt, you should include in your kits silicone port adapters. This allow those with silicone TIP to create a vacuum port much closer to the turbo inlet for a high rate of vacuum. Their about $22 on eBay for a large 1\2 size one with NPT interior thread.

I'm getting one so I can actually run a OCC instead of just catching everything in a Gatorade bottle since my intake doesn't have a VC port.

http://www.ebay.com/itm/191089222289...ht_1831wt_1153


Also anyone try to drill/tap the oil fill cap as a secondary VC port? I know Matt used it for testing, I don't think it would need a baffle

[btstarcher]

Would more vacuum at the valvecover port be beneficial? In boost, wouldn't it help with piston ring seating?

[CosmicArkie]

Originally Posted by redboat Also anyone try to drill/tap the oil fill cap as a secondary VC port? I know Matt used it for testing, I don't think it would need a baffle

Here's a thread to consider:

Nator Valve Cover Breather Tutorial

You can always go retro and get a similar cap from back in the day that has a 90 degree 5/8 inch nipple for the hose which used to run from the valve cover to the air cleaner on those cars. Just tee it into the TIP or OCC.

[darthxar]

I'm really interested in the two can set up like atvfreek has do you offer this @Damond Motorsports; ?

Double tappin' the Moto

[redboat]

Matt would you know the cracking pressure of the PCV is?


Would it be safe to run CC w/out a PCV or Check vavle straight into a vacuum sourced OCC?

[2.0t03speed]

Originally Posted by redboat Matt would you know the cracking pressure of the PCV is? Would it be safe to run CC w/out a PCV or Check vavle straight into a vacuum sourced OCC?

I just gutted my pcv and am running it with my corksport occ. It uses my intake for a vac source and blocks off the intake Mani. I also have a oil cap breather. So far so good.

Sent from my Nexus 5 using Tapatalk

[btstarcher]

Originally Posted by redboat Matt would you know the cracking pressure of the PCV is? Would it be safe to run CC w/out a PCV or Check vavle straight into a vacuum sourced OCC?

Then what about when it's under boost? Positive pressure into the CC is no bueno. Unless I'm misunderstanding you.

[2.0t03speed]

Originally Posted by btstarcher Then what about when it's under boost? Positive pressure into the CC is no bueno. Unless I'm misunderstanding you.

He wants to run it to a vacuum source aka the intake. Not the Intake manifold

Sent from my Nexus 5 using Tapatalk

[btstarcher]

That's not much of a vacuum source.....

[redboat]

Originally Posted by btstarcher That's not much of a vacuum source.....

Originally Posted by 2.0t03speed He wants to run it to a vacuum source aka the intake. Not the Intake manifold Sent from my Nexus 5 using Tapatalk

i agree with both of you. My intake is custom, so I don't have a normal VC vacuum port. But what i'll be doing is installing a port in front of my turbo inlet to have a stronger vacuum source.

My concern is, if I remove the PCV from CC, and run a hose from CC to OCC, with a strong vacuum source from TIP. would this be a problem? or just leave PCV in place?

[2.0t03speed]

Originally Posted by btstarcher That's not much of a vacuum source.....

Ok but from the factory the only place the block see's vac while under boost is from the top of the vc at the most remote point from where the pressure is being created. i don't expect hooking up the pcv to the intake while under load is going to hurt things.

[redboat]

Originally Posted by 2.0t03speed Ok but from the factory the only place the block see's vac while under boost is from the top of the vc at the most remote point from where the pressure is being created. i don't expect hooking up the pcv to the intake while under load is going to hurt things.

it should help out things out, that's my plan too. But i think how the OEM system works, while under boost/load the PCV is closed, which forces excess crank pressure through the VC. So under boost/load the intake port for vacuum that's connected to the VC doesn't really have to be strong, just big enough to absorb all the excess crank pressure and VC pressure coming through ONE port.

But what I think he is saying, is that you'll get a stronger source of vacuum from a closer point on the TIP near the turbine inlet of the turbo.

[btstarcher]

I'm still curious about using a pump of some sort. Then a vent at the valvecover.

[2.0t03speed]

Yep that's why I have a htp intake and a oil cap breather. I don't need any crank case pressure issues. Also from what I've read at higher boost levels the stock pcv will leak some pressure in the crankcase. But it think that varies from car to car.

Sent from my Nexus 5 using Tapatalk

[Tokay444]

The block does not see vacuum under boost, with the oem vent setup. That's why it sucks.

[btstarcher]

Originally Posted by Tokay444 The block does not see vacuum under boost, with the oem vent setup. That's why it sucks.

It doesn't suck. It blows.

[darthxar]

It would be nice to figure out a way to have the strong IM vacuum source during idle and low load, but also have the vacuum source from the TIP during boost. I think it would take at least 2 check valves to make it work right though. If the check valves didn't work damn near perfect, you could end up with a recirculating boost leak from the IM to the TIP under boost.

[himurax13]

Originally Posted by darthxar It would be nice to figure out a way to have the strong IM vacuum source during idle and low load, but also have the vacuum source from the TIP during boost. I think it would take at least 2 check valves to make it work right though. If the check valves didn't work damn near perfect, you could end up with a recirculating boost leak from the IM to the TIP under boost.

The venturi setup from the exhaust seems like the only decent option.

Sent from my SCH-I535 using Tapatalk

[btstarcher]

Or a pump.

[redboat]

Originally Posted by darthxar It would be nice to figure out a way to have the strong IM vacuum source during idle and low load, but also have the vacuum source from the TIP during boost. I think it would take at least 2 check valves to make it work right though. If the check valves didn't work damn near perfect, you could end up with a recirculating boost leak from the IM to the TIP under boost.

Matt Damond has created this set up for sale.

Only problem depends on what type of TIP you have. HTP is the only brand I know of, that includes a secondary vacuum port near the turbo inlet with a 3"+ intakes/TIP's.


I have a 3" Silicone TIP, with a custom intake set up with NO vacuum port. After some searching I stumbled on to one of these and ordered one for my solution. I'll place close to the inlet of my turbo for a go strength vacuum. Once it arrives with my OCC, I'll do a write up.

Silicone Port System | eBay

[Realgib3]

Originally Posted by himurax13 The venturi setup from the exhaust seems like the only decent option. Sent from my SCH-I535 using Tapatalk

At idle and low load, the venturi setup will actually push exhaust gas back up into the VC. For this reason, you have to run a CV on the venturi pipe.