Please not another crankcase ventilation thread. - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 10-24-2015, 04:51 PM   #61
Junior Member
 
Join Date: May 2008
Location: Grants Pass, OR.
Posts: 449
Total Cats: 14
Default

Here is a video of what deezums is saying.

jmann is offline   Reply With Quote
Old 10-24-2015, 09:23 PM   #62
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,999
Total Cats: 1,466
Default

Deezums, please tell me that is you...
aidandj is offline   Reply With Quote
Old 10-24-2015, 09:36 PM   #63
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

I wish it were, but I rate video 5.0 stars. 11/10 with bong hits.

deezums is offline   Reply With Quote
Old 10-24-2015, 09:48 PM   #64
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,677
Total Cats: 1,561
Default

Oil vapors lower the octane rating of the mixture. I choose not to reintroduce them to the combustion chamber.
sixshooter is online now   Reply With Quote
Old 10-24-2015, 09:53 PM   #65
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

That is the point of catch can, which isn't in the video above.

Do you not have a catch can on the slashcut? I would figure it has to smoke or at least smell of oil if it didn't. I pull under an ounce every thousand miles, that's a lot of oil in the exhaust...

Also, for our turbo miata, and any car for that matter, the PCV is closed in WOT. If any oil were to be ingested at that time, it would be whatever was hanging around the second before. PCV isn't dumping oil vapor when it really matters, in boost. If it's vented proper, the crank is cleared fast and in low load areas, so no det.

Unless you have a MAF or air vane, in that case your crank vent/PCV air supply has to be plumbed back to the intake manifold, no breather. Then you want two catch cans, one for PCV, and one for blowby in boost/wot.
deezums is offline   Reply With Quote
Old 10-25-2015, 04:07 AM   #66
Elite Member
 
Join Date: Apr 2010
Location: Newcastle, Australia
Posts: 2,640
Total Cats: 25
Default

Quote:
Originally Posted by deezums View Post
Yeah, and your point is?

At all other points of operation, with a PCV system, that outlet hole is an inlet hole. It is the same exact way on a stock miata valve cover, massive gaping hole through a half-asssed catch can. It goes to the intake past the MAF meter because all air goes in/out of there goes to the intake sooner or later, same as a recirc BOV.

The only reason air exits the hole on said 300hp run is because the PCV is closed, there is no vacuum in the crank. If it were a bitchin' big cube motor doing 300hp at 50kpa map, no blowby would exit said hole.

Come at me bro!
Yeah but why does it matter is there is some vapour hanging around in the case rather than air?

Dann
nitrodann is offline   Reply With Quote
Old 10-25-2015, 06:30 AM   #67
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

Because blowby is harsh crap, water vapor and other stuff that fouls oil, rings, and bearings faster than necessary.

Will thin stuff out like crazy too. See the "My Blackstone results" thread for proof that proper PCV lowers fuel in oil percentage pretty good.
deezums is offline   Reply With Quote
Old 10-25-2015, 10:01 AM   #68
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,677
Total Cats: 1,561
Default

The crankcase vapors are constantly being replenished. Having a breather is the most important thing. Whether it is vented to exhaust or atmosphere or intake matters little.
sixshooter is online now   Reply With Quote
Old 10-25-2015, 11:03 AM   #69
Senior Member
iTrader: (1)
 
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,038
Total Cats: 157
Default

The amount of wrong opinions submitted as fact in this thread are astounding.
TNTUBA is offline   Reply With Quote
Old 10-25-2015, 01:11 PM   #70
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,999
Total Cats: 1,466
Default

Quote:
Originally Posted by TNTUBA View Post
The amount of wrong opinions submitted as fact in this thread are astounding.
What are your right opinions?
aidandj is offline   Reply With Quote
Old 10-25-2015, 02:57 PM   #71
Junior Member
 
Join Date: May 2008
Location: Grants Pass, OR.
Posts: 449
Total Cats: 14
Default

IMO as long as you have a source of air so the crankcase can breathe easily it well work, but having the vapor which contains alot of moisture extracted with suction is alot more effective and beneficial to the engine.
Most here aren't old enough to remember the old days of the engines just having a crankcase vent off of the block to atmosphere. When the rings would get wore out and the engine would have alot of blowby you could pull the valve covers and see cream colored thick formy like gunk which was moisture. So The more vapor you have laying in tthe engine the more moisture is there also.

Last edited by jmann; 10-25-2015 at 03:07 PM.
jmann is offline   Reply With Quote
Old 10-25-2015, 03:02 PM   #72
SADFab Destructive Testing Engineer
iTrader: (5)
 
aidandj's Avatar
 
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 17,999
Total Cats: 1,466
Default

So that's what's all inside the valve covers on my 72. I need to get it some vacuum I guess. I replaced the blocked of breather vent but some vacuum would help I bet
aidandj is offline   Reply With Quote
Old 10-25-2015, 04:57 PM   #73
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,677
Total Cats: 1,561
Default

The moisture is from condensation due to temp changes. Short trips exacerbate the issue. Longer periods of operation cook off the moisture. The same occurs within the trans and differential. This is why it is better to run a car or any piece of machinery rather than store it unless it is a moisture controlled environment.
sixshooter is online now   Reply With Quote
Old 10-25-2015, 06:11 PM   #74
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

Quote:
Originally Posted by sixshooter View Post
The crankcase vapors are constantly being replenished. Having a breather is the most important thing. Whether it is vented to exhaust or atmosphere or intake matters little.
No, they're not.

If you don't have constant positive crankcase ventilation, the only replenishment is blowby pushing more blowby out.

This was my bong analogy, but you all too stupid for that. The smoke is blowby, and the non-positive crank vent is represented by the bowl being closed.

The bong never gets clear, any and all smoke/blowby that leaves the system does so because more blowby came in behind and pushed it out of the crankcase. If you were to shut off the car at any time, any and everything hanging there is condensing down to the oil, guaranteed.

This doesn't happen with PCV. Right before I shut my engine off I'm at low load idle, any moisture in the air is burned, it doesn't hang and settle into the oil anywhere near as much.

This is why there has always been positive crank vent, before PCV it was draft tubes in conjunction with valve cover breathers. Never in the modern existence of automobiles has a manufacturer deepened on blowby to remove blowby, because it's straight Pat levels of ******* stupid.

deezums is offline   Reply With Quote
Old 10-25-2015, 06:39 PM   #75
Junior Member
 
Join Date: May 2008
Location: Grants Pass, OR.
Posts: 449
Total Cats: 14
Default

AsLonger periods creates less moisture as the car warms up but it doesn't COOK off moisture, it just creates less as the motor warms up, and it is still creating moisture, just less of it which still needs to be extracted along with the pressure for good ring seal as the more oil that get past the rings to get hit with combustion temps the more the temp diff is with the oil temp and thus the more moisture is created. I have worked on cars that have set in terrible conditions for years and have never seen moisture in a tranny or diff when drained or an engine for that matter. I have seen the oil get thick and gummy from solvent evaporation from time, but never any water to speak of. It takes theoil getting hit by higher combustion temps to create the majority of the moisture so the better the rings stay sealed the less the oil that well get by the rings to hit combustion temps so positive extraction is good. As Deezems says even in the old days of just a vent off the block there was a ventd cap on the valve cover or the fill pipe for venting.
jmann is offline   Reply With Quote
Old 10-25-2015, 10:24 PM   #76
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,677
Total Cats: 1,561
Default

When you cool the air within an engine, transmission, or diff, what does it do? Does it expand or contract? I believe it contracts. Fresh air enters through the vent cap as the components cool. This introduces more moisture.

Do you have moisture on your car some mornings? How about excess water vapor in your exhaust when you first crank your car? Where do you think it comes from, that dear, sweet moisture? And how does it get back inside your hot exhaust pipe after you have shut off your car? Magic perhaps? Spontaneous generation? I happen to believe that contraction of the gasses draw fresh air inside. But that's my opinion.

I also have drained moisture laden creamy oil out of my Allstar Performance catch can but none from my oil pan. It is peculiar that the moisture can make it there with nothing but a steady flow of warm gasses continuously pushing them away from the engine. Many CFMs of continously flowing gasses continuously pushing vapors away from the engine during the entire time it is running are confusing to who? Apparently the fellow who believes it is constructive to insult moderators has difficulty with the concept.

The pcv arrangement is a construct of the clean air movement and not the automotive performance industry. Believe as you wish.
sixshooter is online now   Reply With Quote
Old 10-25-2015, 10:53 PM   #77
Sadfab Union President
iTrader: (3)
 
Join Date: May 2014
Location: Kansas
Posts: 2,690
Total Cats: 113
Default

If you have moisture on your car during the mornings it's because the dew point has been surpassed overnight, and therefore relative humidity is at one of the highest points it gets during the day.

When you start your car, it eats water in the air as well as a byproduct from combustion, that is where the moisture in the exhaust comes from. As the car reaches temperature the exhaust tubing temp rises, so water vapor can no longer condense on the cool exhaust piping.

You live in Florida, so you don't get many days to see the water vapor all day long when it's really cold out, but it's a constant by-product of burning hydrocarbons. It's a constituent of blowby, having less of it in the crank when the engine is off is going to be beneficial.

I don't know how to acknowledged the catch can water vapor, other than it's a part of blowby and a sign the can works. There's a lot more oil in the pan, and as it gets hot the water will evaporate out of it, even more so with more air running through the crank...

PCV replaced draft tubes, because clean air movement. Crank flow has always been a thing. If what you say is true, why do automakers go through all the trouble of PCV? They could just as easily plumb the vent to the intake, let the blowby push itself out to be burned. The end goal is the same, right? No crank blowby leaves without being burned.

Nope, the extra longevity means mfrs go through all the trouble, and hipo cars sometimes get catch cans when pushing pump gas limits. It gives oil all the extra edge it can to last longer for most daily driver cars.

If getting banned for arguing for what's been apparent for decades gets me banned, so be it.
deezums is offline   Reply With Quote
Old 10-25-2015, 11:20 PM   #78
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,677
Total Cats: 1,561
Default

You were personal in your name calling towards me. Perhaps it would be useful to develop in yourself the ability to discuss topics without resorting to leaving the topic itself. Grow from this opportunity.

I have no problem with differences of opinion or understanding regarding technical issues. Please keep things technical.
sixshooter is online now   Reply With Quote
Old 10-26-2015, 08:45 AM   #79
Senior Member
iTrader: (1)
 
Join Date: Jan 2011
Location: Chattanooga, Tn
Posts: 1,038
Total Cats: 157
Default

Quote:
Originally Posted by aidandj View Post
What are your right opinions?
If they are right....they aren't opinions....are they?
TNTUBA is offline   Reply With Quote
Old 10-26-2015, 09:34 AM   #80
Moderator
iTrader: (11)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 15,677
Total Cats: 1,561
Default

Wiki wiki wiki wiki.

Quote:
The first refinement in crankcase ventilation was the road draft tube, which is a pipe running from a high location contiguous to the crankcase (such as the side of the engine block, or the valve cover on an overhead valve engine) down to an open end facing down and located in the vehicle's slipstream. When the vehicle is moving, airflow across the open end of the tube creates a draft that pulls gases out of the crankcase. The high location of the engine end of the pipe minimises liquid oil loss. An air inlet path to the crankcase, called the breather and often incorporated into the oil filler cap, meant that when a draft was generated at the tube, fresh air swept through the crankcase to clear out the blow-by gases.
Large diesel engines use a draft tube and breather to this day.
Quote:
During World War II a different type of crankcase ventilation had to be invented to allow tank engines to operate during deep fording operations, where the normal draft tube ventilator would have allowed water to enter the crankcase and destroy the engine.[4] The PCV system and its control valve were invented to meet this need, but no need for it on automobiles was recognized.
In 1952, Professor A. J. Haagen-Smit, of the California Institute of Technology at Pasadena, postulated that unburned hydrocarbons were a primary constituent of smog, and that gasoline powered automobiles were a major source of those hydrocarbons. After some investigation by the GM Research Laboratory (led by Dr. Lloyd L. Withrow), it was discovered in 1958 that the road draft tube was a major source—about half—of the hydrocarbons coming from the automobile. GM's Cadillac Division, which had built many tanks during WWII, recognized that installation of PCV on vehicles could bring the first major reduction in automotive hydrocarbon emissions. After confirming the PCV valve's effectiveness at hydrocarbon reduction, GM offered the PCV solution to the entire U.S. automobile industry, royalty free, through its trade association, the Automobile Manufacturers Association (AMA).[citation needed] The PCV system thus became the first real vehicle emissions control device.
Positive crankcase ventilation was first installed on a widespread basis by law on all new 1961-model cars first sold in California. The following year, New York required it. By 1964, most new cars sold in the U.S. were so equipped by voluntary industry action so as not to have to make multiple state-specific versions of vehicles. PCV quickly became standard equipment on all vehicles worldwide...
So, the PCV valve is an emissions device unless you are fording a river with a tank. And it is implemented because it is federally mandated for the control of hydrocarbon emissions. This is what I stated previously.


Anyone removing an oil filler cap from a typical running engine, even one equipped with a PCV valve, could certainly attest to the fact that blow-by exists in far greater volumes than the PCV valve is allowing the engine to ingest. This blow-by is constantly increasing in volume as the engine is running (just like exhaust because much of it is just exhaust that has made it past the rings) and can be piped to an oil separator catch tank and vented to atmosphere if one is unconcerned with emissions.

I am simply stating, again, that the consumption of crankcase vapors and the introduction of outside air to an engine crankcase while it is running is not a performance benefit but an ecological one. And I choose not to contaminate my combustion chambers unnecessarily with oil and other foul byproducts of the combustion process. I have seen the nasty trail within an intake manifold around the inlet for the PCV hose and do not wish to add those elements to my freshly rebuilt engine.
sixshooter is online now   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Engine swap, now billowing smoke, do I need an oil restrictor? 6strngs DIY Turbo Discussion 15 10-27-2015 02:16 AM
Turbo stuff for sale at [email protected] this weekend gesso Miata parts for sale/trade 18 10-23-2015 10:26 PM
Engineering project ideas MartinezA92 Insert BS here 21 10-08-2015 11:38 PM
Turbo manifold and dowpipe T25 LucaCarMods WTB 0 10-03-2015 06:58 AM
starting issue Johnny Tater Engine Performance 3 09-23-2015 07:10 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 05:56 PM.