Well I do hope you post your findings, don't be dissuaded from doing so because of forum posters being presumptive. It would be very interesting to see solid testing and the readings at various stages of venting.
Measuring crank case pressure
- Thread starter doublespaces
- Start date
I apologize if this sounds stupid, but have any of you had a chance to pour water through the internal pcv system within the VC? If you have your head ports plugged, there's no reason to use the already plugged pcv port on the back of the cover. If the only purpose for the second catch can is to pull vacuum under no-load situations, then thats easily done with two more check valves not a 2nd can.
Here's the way I see it, and why I agree with @doublespace that this system is over thought, and perhaps over sold. Here's a small illustration.
The white line follows the head ports which 90% of us have plugged, let's assume so in this situation. If you pour water down the green hole thats plugged at the factory it exits through the 6 headports, and the red circled vents freely without a valve. The blue circled represents the flapper side. When water is poured through the flapper side it exits straight through the red circled ports unrestricted. When you blow through the green side you can feel your breath coming from the blue side, and vice versa.
Assuming you have your head ports plugged, all gasses flow freely through both blue and green holes. So the the hell are we running both sides, and two catch cans? If it's solely for pulling vac then like I said.. that takes two extra check valves, not a 2nd can.
Here's the way I see it, and why I agree with @doublespace that this system is over thought, and perhaps over sold. Here's a small illustration.
The white line follows the head ports which 90% of us have plugged, let's assume so in this situation. If you pour water down the green hole thats plugged at the factory it exits through the 6 headports, and the red circled vents freely without a valve. The blue circled represents the flapper side. When water is poured through the flapper side it exits straight through the red circled ports unrestricted. When you blow through the green side you can feel your breath coming from the blue side, and vice versa.
Assuming you have your head ports plugged, all gasses flow freely through both blue and green holes. So the the hell are we running both sides, and two catch cans? If it's solely for pulling vac then like I said.. that takes two extra check valves, not a 2nd can.
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You got the colors backwards unless I'm misunderstanding you.
The best way to understand this concept is to look at an aftermarket VC, those red and green holes have no internal structure. You can poke your finger in one hole and out the other. With your head ports closed, I see them both as outlets only. Nothing needs to go inward, no check valves are needed. The stock VC can be operated in the same way (I'm doing it right now, flapper and pcv port are outlets only, no check valves).
Only thing you need is a good catch can and a place to send the fumes.
I know we understand this, others may not. Fortunately, although I got the two Colors mixed up the point still stands. Actually, you can't stick your finger all the way through nor reach around and touch your other finger, your fingers stop because it gets routed through the red circled ports.
I'm not trying to wrap my head around how it works doublespace. Just pointing out there's no reason at all for a second can and agreeing with you that the whole pcv system is over thought.
The reason I mention the extra valves are for people that want to pull vacuum at idle rather than vta. Which everyone uses a second can for. You can use one can, a check valve, and T into the throttle body, and it will pull vac during idle, and vta under load without charging the catch can.
I'm not trying to wrap my head around how it works doublespace. Just pointing out there's no reason at all for a second can and agreeing with you that the whole pcv system is over thought.
The reason I mention the extra valves are for people that want to pull vacuum at idle rather than vta. Which everyone uses a second can for. You can use one can, a check valve, and T into the throttle body, and it will pull vac during idle, and vta under load without charging the catch can.
True, I was talking about an aftermarket VC.
I know, just giving my thought process for others to digest.
This actually produces codes or howling seals on some vehicles unless you run a vacuum break like the one offered by VTT or the flapper valve restrictor itself.
To clarify, one check valve into the can will produce throttle blade codes on some cars if there isn't sufficient restriction of airflow coming back into the engine. This is a catch can variable sometimes, some are more restrictive than others.
If you put a check valve on the outlet of the VC, you need a vacuum break or you get the howling seals. Not in all cars but many.
The answer is to stop ingesting anything into the engine period. All of this becomes very simple as none of this matters nor needs to be understood.
If you put a check valve on the outlet of the VC, you need a vacuum break or you get the howling seals. Not in all cars but many.
The answer is to stop ingesting anything into the engine period. All of this becomes very simple as none of this matters nor needs to be understood.
Rodger dodger. Cheers *clink*
Definitely agree with the throttle body pulling too much vac. I should have been a tad more clear on the type of check valve. That being said the majority of check valves are so damn small they're practically metered already ie; Toyota pcv valve.
Definitely agree with the throttle body pulling too much vac. I should have been a tad more clear on the type of check valve. That being said the majority of check valves are so damn small they're practically metered already ie; Toyota pcv valve.
We're not quite on the same page here, theres no check valve in the can, and youre mistaken on where im putting the check valve. I'll message you real quick.
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I'm messaging while at stop lights so I'm skimming. Feel free to elaborate on where the check valves go. I haven't thought about using a single catch can with a check valve because there is little or no reason to do it to begin with.
If you have any meaningful vacuum in your intake you have a restriction. Its why diesels use a restriction gauge which is just a spring which sucks closed with vacuum to let them know when it time to change the filter. You are looking for no vacuum in your intakes. If you want to measure crankcase pressure I would just do that instead of bothering with measuring intake vacuum. If you have a decent intake on the car it's not going to show anything.
This makes perfect sense. Intake is still a good place to route to for environmental reasons, but wont pull vacuum if intake is sized appropriately. Thanks for a very clear example.
So just to be clear, you're saying that at idle the intake manifold shouldn't pull any vacuum if sized correctly?
Hopefully I read that wrong and you can correct me, because that would mean this engine magically has no scavenging effect under no-load conditions. Which is exactly what causes the restrictor you mention to function properly.
Hopefully I read that wrong and you can correct me, because that would mean this engine magically has no scavenging effect under no-load conditions. Which is exactly what causes the restrictor you mention to function properly.
You read it incorrectly. I read the OG post the same way as you just read that one and got flamed as being stupid or a troll. Intake is being used to mean turbo inlet pipe, not the charge piping or intake manifold.
Huh? Intake Manifold will always be referred to as manifold vacuum. Intake is the intake tube which is clearly what Tyler was talking about in his post. If you want to measure intake manifold vacuum just look at your mhd boost at idle.
I think we just got cross rutted a little bit that's all.
Im speaking with what's here on page four, no clue on what tyler mentioned in his OP regarding the cold air intake side, because it doesnt apply to the current conversation on this page. On page four here we (or at least I) are simply talking about eliminating a catch can since one can be reconfigured to work as 2.
Cheers!
Im speaking with what's here on page four, no clue on what tyler mentioned in his OP regarding the cold air intake side, because it doesnt apply to the current conversation on this page. On page four here we (or at least I) are simply talking about eliminating a catch can since one can be reconfigured to work as 2.
Cheers!
A no vacuum situation is zero flow.
Or if you see zero vacuum, get a better gauge.
All moving air will either create vacuum or pressure.
So if you'll excuse me... Say on an M18 valve cover. Both ports go to a dual catch can and then both vent to air. What separates the low and the high ? Does this mean I could run only 1 catch can ? I'm confused.
I agree with this, mostly. I've even asked someone who measured this with a mechanical gauge and got nothing (at idle). There is also the question, why do people remove their filter or use very large ones, much larger than most of is? Clearly they are seeing benefit to running a massive filter to increase the surface area and reduce restriction. If there is restriction at high boost levels (aka high volume compressor CFM?) then there will be some vacuum generated, although it might be quite small. This supposed vacuum idea has been used as a sales pitch, so I'd like to quantify it in terms the value it brings for that specific marketing point.
No hard feelings, I think I was having a bad day. Facebook life drives you to the brink. Got people demanding me all day to act on their reports immediately, as if I'm their slave. Much easier to kick them out and stop paying the therapist.
Also, I spoke with @MoistNapkin he explained to me what he is doing. With a variable or two, I believe it could work for people who would like to run a single catch can and have what is effectively the same as a two can setup with high and low side.
Personally, I've taken it a step further:
This is all you need.
Anyone can understand this system, the only people who won't understand this are people who have been lead to believe it needs to be more complicated. But again, I'm going to take a little bit of data and see if this is sufficient. As you can tell, there isn't much labor or R&D to sell here.
This is your current setup?
If so, then in my opinion that is great. If you've got your head ports plugged, the only thing I'd suggest is instead of routing them to the air, route them to your intake pipe(pre turbo, not charge pipe) or run a hose from the cans under your car a bit so it doesn't smell by getting into your cabin filters.
This is essentially what I'm suggesting people should do, except my picture has just a single line. I'm going to test it with up to three ports however(two on back, one on front).
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