Crank Case Ventelation/Oil Breather

[modok]

[Eaallred]

[builtbychevy]

[builtbychevy]

[Alpha_Maverick]

BTW, modok, I threw away two of those ford AIR valves when I stripped the emissions equipment off of my old truck. I knew I should have kept them for something!
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[modok]

So you put the engine in an iron lung and pressurize it to 100 PSI?

I wanna see a pic of that
But I get what you mean, that is a step above.
Do you put in all the seals backward?

We don't even have seals you know. My engine I have to add the oil slowly so it doesen't pour out of behind the pulley. Shoot, if I added any vac to the crank case it would just suck dirt into it.

It appears subaru also uses IN at the valve covers and OUT at the crankcase
http://www.subaruoutback.org/forums/attachments/pr...system.jpg

[builtbychevy]

[58 Plastic Tub]

I hate oil leaks. Several years ago, I built a big (like, a couple gallons) sealed breather box with everything I can vent into it running into the bottom. Off the top, I connected to the air-cleaners, but fabbed Bernoulli tubes that stuck into the velocity stacks to create some pull. The tubes really worked at creating a mild vacuum, but sucking oil vapor into two carb throats is something less than perfect.

Next, I did the 3/4" tubes running from the 3-4 valve cover back to the sump, as was the recommendation when the "valve cover/oil" video was new a few years back. I'm not a drag-racer, my Type 1 is in a speedster replica, and as a result gets treated like a sports car. I never thought the tubes were all that great on the street, as I'm pretty sure that the oil runs backwards up them during hard turns.

Last year I converted to dry-sump. I vent the dry-sump tank into the ginormous breather box. Part of the dry-sump project was a new exhaust (so that it would clear the pump). This allowed me to install a Moroso check-valve and Bernoulli tube setup in tailpipe, so I could vent the box into the exhaust instead of into the carbs. This set-up draws a much stronger vacuum than the Bernoulli tubes in the air-cleaners did.

Thinking about it, Id probably be better off to keep the valve-cover vents open, and just vent the crankcase into the box (with the vacuum on it), but frankly this is soooo much better than the little bitty breather box I started out with, that I'm finally in a happy-place. A properly designed PCV system would be the best solution, but I have no idea how to properly size the valves and orifices, so it probably won't get done for some time.

I realize this isn't exactly what the original poster was asking about, but this is the "high performance" section of the website, so there you have it.
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Stan Galat
"A single point in isolation is a reference point. Two points is a line. Three points is a trend. Trends don't lie."

[Steve Arndt]

A test I performed to see if the exhaust scavenge Pan E-vac would work post catalytic converter and pre muffler (straight through style):

http://www.youtube.com/watch?v=0xi6MilZUBA


Link


I have a CB breather tower filled with extra baffling (scrubber pads). The plan is to replace my open vent lines that currently go to the air filters with the exhaust scavenge. My case is fully sealed up.

I am going to test the system with no venting IN to the case at first, just the vacuum into the exhaust. I hope to avoid valve cover vents.

[raygreenwood]

Again....Even though I realize...that this thread is about a 1600.....I do suggest that for reference and education some here should take a look at the vacuum diagram and crancase ventilation components of the D-jet injected type 4 used in 411/412 and 914. Very well designed.

I also realize that without a pump or venturio of some sort it cannot work on a general carbed system. The carbs do not generate enough vacuum...or at least different vacuum.

in the type 4 system...reed valves and check valves are not necessary. It has to do with proper sizing of orifices.

PCV fresh filtered air comes from a special port in the air cleaner ...which limits its flow. It flows through 12mm Id hose to a splitter with a fire trap, goes to each cylinder head rocker box through 12mm ports in the top, is PULLED through the rocker box and through the PR tubes, Exits the top of the case through the cast in "Z" baffle in type 4 cases...which arrest most of the oil.....then through the chimmney...which has yet another very effective oil baffel....through a PCV valve....through a 12mm ID hose..directly into the center manifold.

The location in the plenum where this vacuum supply line/vent plugs in will never see less than about 5-8"hg even at WOT. typically it averages about 10" ass a minimum.

The OCV valve sucked. Many of us relace it with a 3mm fixed orifice...which is ideal and much smoother to tune AF mixture around as its flow is a fixed component.

The flow ability of a fixed orifice at 10-15" hg in CFM is actually fairly high...much higher than the volume of the case and heads...so they get significant scavenging.

No valves necessary. I would think and exhaust venturi would do this much better on a carbed engine. Ray

[Eaallred]

[runamoc]

[Alpha_Maverick]

it's a 1600, dave

and yeah. I know. I'm waiting on getting my cylinder heads back, and I'm running out of productive things to do.
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[vwracerdave]

It is amazing how 2 people can have completely different results. I've been bracket racing 20 years and have never had any problems. In my drag race Dunebuggy I've run 12.20's shifting at 7300 RPM. I don't have any oil leaks and never have more then a teaspoon full of oil inside my breather box. On my street Ghia with 2165 I shift at 6700 RPM and just a cheap Bugpack oil breather and not a single leak and no oil inside the breather box. I vent both valve covers and the factory oil fill.

Alpha, you are so much over thinking and grossly over engineering your 1500 that it has become a laughing soap opera reading your post. All you need is the stock ventilation system.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK

[Alpha_Maverick]

I'm just going to ignore the illogical and race-only suggestions (I use a mechanical fuel pump, chevy)

Another option, for me, would be to use the front (FIF) vent to push into the valve cover, then use the other in the breather line, to pull a slight vacuum in the case. I'd have to run a sand seal for that, so I don't think I want that. Just thought I'd share.

Here's the discussion of the krank-vents at STF:
http://www.shoptalkforums.com/viewtopic.php?f=15&t=118958&hilit=krankvent

I think my best bet is to tap the front driver's side and the rear passenger side. The passenger side would be under the generator, so it'll be decently hidden. Put a 90° elbow on it, then into the krank-vent, then have a hose go around the passenger side of the fan shroud. Even if I don't use the vents right now, I can just plug them until I can afford to play with check valves, which I'm going to do.

Another note: since I'm not going sand seal, I'll never achieve crankcase vacuum, so using an external breather box or vacuum pump would be pointless. The goal here would be to get the oil back from the 3-4 rocker box, without introducing MORE pressure to the crankcase.

Anyway, I'm just babbling now. I'm gonna go see if I can design my own krank-vent
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[modok]

[builtbychevy]

[builtbychevy]

15" Hg or Mercury is not the same as psi.

Too much negative crank pressure with loaded engine can cause problems in some engines such as an SBC for splash piston pin oil(can cause oil starvation for that)

The oil pump becomes more efficient with a quality vacuum pump.

We test our engines seals usually by evacuating the air to -200"Hg and measure it. Any gauge that goes on my engine must be Certified to +or - 1% for fuel, oil, or vacuum.

That means your oil pan, valve covers, oil cooler, EVERYTHING must be assembled perfectly!

I made reeds for my draw through Ra Jay Martin Turbo using spring steel and shoulder bolts from Mcmaster. Remember that reeds do wear out!
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Josh Smith
Dirty Racing & Rods
My Store: www.dirtyracingandrods.com
My Blog: http://blog.dirtyracingandrods.com/dirty-racing-rods-the-paradise/the-vw-squareback-progress/

[builtbychevy]

You don't need a reed valve in the valve cover. I have a baffle inside of my breather box so basically the oil just falls back down the main tube to the sump.

One time my 3/4 valve cover came loose maybe I was drunk? but in two miles I lost 1 quart. I only noticed it because of grey smoke on my headers. The grey smoke is why I dump all of my overflows on my muffler on the passenger side(so I can see it happen).

Valve covers flood especially if your oil pump is too big. In high quality engines we install oil restrictors to reduce oil in the valve cover or to the lifters/ rockers. Next time you split the block you need to fabricate a windage tray with a crank scrapper. You may atleast build a baffle to partially block your pushrod tubes.

On our high performance engines even BMW... We enlarge the cylinder head drain backs, install screens to prevent broken roller rocker parts from falling onto the cam, Install extra drain backs in the back of the cylinder head, install a vent/drainback from the valve cover to the fuel pump port, and maybe some more drainbacks/ vents from the oil pan to the valve covers.

Oil starvation is very important on any engine. Especially when we run our wetsumps a little bit low on oil to fight windage. That's why I use a 13qt oil pan on my daily driver.

My breather ports on valve covers are usualy installed over the front drainback or in between the rockers. Most rockers are splashed oil or have squirters. A real simple baffle partially blocking the vent always helps.

If you are racing and your valve covers are flooding you NEED TO FIX THAT. I would add some extra vents and drains backs!

Remember that windage causes parasitic losses and generates frictional heat(allot)!
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Josh Smith
Dirty Racing & Rods
My Store: www.dirtyracingandrods.com
My Blog: http://blog.dirtyracingandrods.com/dirty-racing-rods-the-paradise/the-vw-squareback-progress/

[Volfandt]

The old Kohler K singles & Magnum twins used a reed valve in the block to regulate the crankcase pressure and the newer OHV twin Commands uses a reed valve per head and a vent line to the carb. Pretty simple and those parts areadily available.
http://www.ereplacementparts.com/reed-breather-p-580193.html?gclid=CMGQ68KllLYCFQf0nAodWEkAuw
http://www.ereplacementparts.com/reed-breather-p-572135.html?gclid=CNuo1s6mlLYCFQk4nAod4goAqg
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1972 Karmann Ghia, the Dragon slayer....