Another Catch Can Thread - 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 11-16-2011, 08:09 PM   #1
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default Another Catch Can Thread

After browsing around about catch can, I decided to put one together. I am not FI'd yet, so this is just using a "compressor/air filter" from lowes and two silicone hoses. Anyways, so I used a T fitting to connect the passenger and driver side together and then run that into the catch can. Is that legit? I noticed everyone runs two lines into the catch can, rather than joining them. Why is that? From what I can tell, they both seem to be exit ports right? or is the passenger side dual purpose in that case?



Attached Thumbnails
Another Catch Can Thread-imag0571.jpg   Another Catch Can Thread-imag0572.jpg  
Seefo is offline   Reply With Quote
Old 11-16-2011, 09:11 PM   #2
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,109
Total Cats: 518
Default

Especially for NA, I believe the standard is the stronger 323 PCV valve and an otherwise stock system. Street FI can put a check valve between the inlet manifold and valve cover to prevent the boost from damaging the PCV valve, and causing leakage, therefore pressurizing the head.

Tracked FI cars generally require larger (-6 or -8) lines from both sides of the valve cover going into a catch can that may or may not drain back into block via the stock drain port.

All of these have known to fail in either of these situations, search for "catch can" and you'll get a couple dozen unanswered threads, yet each have dozens of replies.
curly is offline   Reply With Quote
Old 11-16-2011, 09:22 PM   #3
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

I am not even running a PCV valve. just straight out, into the T and then that into the can + filter and VTA.

What do you mean by failure btw?

I just get the feeling from reading around, that its probably a good idea to keep vacuum on the crankcase when Naturally aspirated. or am I mistaken here?

Last edited by Seefo; 11-16-2011 at 09:42 PM.
Seefo is offline   Reply With Quote
Old 11-16-2011, 10:00 PM   #4
Former Vendor
iTrader: (1)
 
Join Date: Nov 2011
Posts: 31
Total Cats: 0
Default

In my street Honda Im running 4 off the valve cover and 2 drain back on the block. That work as vents when the car is under load.
whispering eye is offline   Reply With Quote
Old 11-16-2011, 10:22 PM   #5
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

Quote:
Originally Posted by whispering eye View Post
In my street Honda Im running 4 off the valve cover and 2 drain back on the block. That work as vents when the car is under load.
Not sure? you have 4 PCV ports? that's a lot. I am not draining it back into the block, thats for sure. most of what comes out is oil and water, and I don't want water in my oil.

Further reading on topic, It seems that for N/A track car (which is what I am for now), it would be best to run the catch can off the breather and keep the PCV (under street driving and low throttle, I would keep the benefit of vacuum helping evacuate stuff. Under high throttle all the gases would be out into the catch can and VTA).

Or perhaps, I can just hook up the PCV port (with no PCV) into the catch can during track events for more breathing.

Someone tell me if I am silly or not.
Seefo is offline   Reply With Quote
Old 11-16-2011, 11:17 PM   #6
Former Vendor
iTrader: (1)
 
Join Date: Nov 2011
Posts: 31
Total Cats: 0
Default

I'm sorry not PCV ports, but breather bungs coming off the valve cover. Its better to relive the engine of crank case pressure. If you are willing to eliminate the PCV during races why not do eliminate it all together?
whispering eye is offline   Reply With Quote
Old 11-16-2011, 11:43 PM   #7
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

Here is the way I am seeing PCV under vacuum:

Advantages:
-Helps with low throttle/cruise evacuation

Disadvantages:
-less evacuation porting under heavy throttle, where the PCV will close and the breather does all the work.
-The crankcase gases under low throttle/cruise are much less than under heavy throttle/track use. So we are effectively giving up some when it matters most, to gain some when its not as important...

I just question the logic behind it, as PCV wouldn't be used if it wasn't without merit. At least in naturally aspirated applications.

At this point, I think I am going to run without PCV this weekend (RA, full/high throttle time is probably the most out of any event I can drive to), but keep two catch cans. just so I can see how much I collect from each hole. Then run a week in the same configuration, but daily driving and see which side collects more. Then one more week with the PCV under vacuum and compare a third set. I think that would be a good measure of what is working under which conditions...Unless someone can shoot a hole in this "theorizing"
Seefo is offline   Reply With Quote
Old 11-17-2011, 02:43 AM   #8
Senior Member
iTrader: (9)
 
Join Date: Sep 2009
Location: Yamato Japan
Posts: 692
Total Cats: 26
Default

I may be wrong, but I thought that the PCV system still evacuated the crankcase even under high load due to the air rushing through the intake and past the PCV port creating a low pressure area relative to the crank case (even though the engine is not "pulling vacuum" per say). You still have a mass of air and it's moving fastest at WOT.

As for the vent system itself: I've read some engineering papers on the subject (best I can offer not being an engineer or being on a baller *** racing team to really test this) and they suggest that a vacuum on the crank case pulls rings toward the cylinder walls and helps with sealing as well as prevents pressure build up that can lead to premature seal failure (like front/rear mains, oil pan,etc). Certainly if you open any issue of Car craft, or some such publication, they'll show you a big block v8 that gained 20whp from a $500 vacuum pump they ordered off jegs.

From my experience in rx7 land I can tell you this. Turbos create more blowby and thus contaminate the engine oil quicker (especially apparent in rotaries). As such its considered acceptable to run them with no PCV and a catch can vented to atmosphere, because the extra pressure on the crank case will evacuate it anyway.

What people have learned on the track is, you need both sides vented otherwise, if you turn away from your vent, the pressure has no where to go, and you fill your catch can with oil. I know of some RX-7 guys that couldn't go longer than a session before their catch can was overflowing, adding another vent on the passenger side of the engine totally eliminated this.

What you can be sure of is this: you definitely want the left and right side of your engine vented. And even though it's not entirely necessary, you should WANT vacuum on your crankcase. you NEED at least an atmospheric vent. For vacuum, you either need an intake PCV system, or an exhaust scavenge system. If you don't get your vehicles emission tested, the exhaust system is clearly superior. Otherwise, just run it through the intake and deal with a slightly dirtier intake manifold.

Your choice, the environment or your internals? For my play vehicles I go the exhaust route.
tasty danish is offline   Reply With Quote
Old 11-17-2011, 04:29 AM   #9
Elite Member
iTrader: (6)
 
Join Date: May 2011
Location: Lebanon, TN
Posts: 1,668
Total Cats: 63
Default

Is it wrong to connect the pcv valve as per normal with lets say an "perfect" one way valve. Vacuum in cruise/closed under boost. The driver side to the turbo intake through a catch can. IE; vavle cover to catchcan to intake? Or completely remove the PCV crap, hook both lines to the catch can, then to intake. Keep the crank case under some vacuum. Not fill intake with oil via a catchcan. The later is my plan. Been reading a lot about these systems and the later senario makes the eco ***** scream but not try to hang you as much as the exhaust vent route. Plus the exhaust route isn't really street car/easy/the direction I'd want. The strait vent to atmo cans don't provide any vacuum and no catchcan runs the "hey my intake is full of oil" conversation.
TorqueZombie is offline   Reply With Quote
Old 11-17-2011, 08:37 AM   #10
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

^well for you, I think you have to consider the amount of boost. Eventually too much boost and you could end up pushing air the other way (from the intake into the crankcase through the PCV), and thats not good from what I have been reading on here. in your case you have pressure in the intake manifold and pressure in the crank case. Since pressure goes from high to low, the intake manifold pressure will want to move to the crankcase. Thats why some guys move to the 323 GTX PCV, which is stronger and can take more boost.

I don't think the PCV is open at high throttle/low vacuum. At least, everything I have read indicates that it shouldn't be open if the breather is doing its job. As for the vacuum and all that, yea I totally agree vacuum is good, and yes there is plenty of drag cars that run a vacuum pumps to help with ring sealing and get power out of it. but at the same time, those cars are N/A, running ridiculous amounts of displacement, power and compression, so their blowby is plenty high, and they are still running VTA (vacuum pump to catch can to a filter to VTA).

Plus, there is a few things different here: First at high throttle there is little if any vacuum in the intake, so technically you are not gaining any vacuum benefits during that period of time. Those vacuum pump drag cars still are, since the vacuum pump works regardless. So they don't have anything to worry about, other than making sure the pump can evacuate more crankcase gas than the pistons can create (otherwise they would be pressurizing the crank case). I will look into the exhaust route, but the issue is that I wanted to setup a catch can now that way when I went FI'd I would already be prepared. Too bad it had to be this complicated lol. Has anyone ran a vacuum pump on a miata?
Seefo is offline   Reply With Quote
Old 11-17-2011, 09:40 PM   #11
Former Vendor
iTrader: (8)
 
Join Date: Sep 2011
Posts: 487
Total Cats: 4
Default

Running a pump is useful on a NA car. How ever can be expensive and bulky. However one thing you could do now is run a check valve to the exhaust, install it at an angle in the exhaust system. The exhaust will create a vacuum thus assisting in the evacuation of crank case pressure. We installed this same system on a Twin Turbo SRT-10 Truck we built, and it worked flawlessly.
This is a great option if you are NA or turbo.
We tend to use catch cans or Tanks on our personal and customers cars. Your main goal here is to release the crank case of the pressure buildup under load. Helping the rings to seal and help create more power.

Here is a link to a universal kit for Exhaust evacuation system.
Clicky here!
Renown Performance is offline   Reply With Quote
Old 11-17-2011, 10:05 PM   #12
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,114
Total Cats: 351
Default

Or make one of these:
Attached Thumbnails
Another Catch Can Thread-dry-sump-kit.jpg  
hustler is offline   Reply With Quote
Old 11-17-2011, 11:02 PM   #13
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

^dry sump...because race car. Sure, Let me get on that after I make 600 whp.

I will look into the exhaust stuff.
Seefo is offline   Reply With Quote
Old 11-17-2011, 11:35 PM   #14
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,370
Total Cats: 1,332
Default

Quote:
Originally Posted by Renown Performance View Post
Exhaust evacuation
Exhaust evacuation is explicitly banned by the single largest road course sanctioning body. (SCCA GCR 9.3.38) Suggesting it to a road racer is poor practice IMO.
Savington is online now   Reply With Quote
Old 11-17-2011, 11:49 PM   #15
Former Vendor
iTrader: (8)
 
Join Date: Sep 2011
Posts: 487
Total Cats: 4
Default

Great looking out Savington. Like I said we typically suggest and use catch cans and tanks. We the only time we have used them was with that SRT-10 truck, and that was his choice. Just throwing ideas out there.
Renown Performance is offline   Reply With Quote
Old 11-23-2011, 10:14 AM   #16
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

Quote:
Originally Posted by Savington View Post
Exhaust evacuation is explicitly banned by the single largest road course sanctioning body. (SCCA GCR 9.3.38) Suggesting it to a road racer is poor practice IMO.
I appreciate that Savington. I ran the catch can on the breather for the RA weekend...and not a single drop in it. I will update as I change the setup for dec. 3-4 at RA also. I think I will put both PCV and driver side to a catch can and then keep it under vacuum, just for ***** and giggles.
Seefo is offline   Reply With Quote
Old 11-23-2011, 11:06 AM   #17
Elite Member
iTrader: (12)
 
GeneSplicer's Avatar
 
Join Date: Sep 2009
Location: Birmingham, AL
Posts: 2,006
Total Cats: 147
Default

Be sure to catch me - I'll be there and we can overlook catch cans. Also talk about maybe getting a MC going and talk with some of the other Miata guys there?
GeneSplicer is offline   Reply With Quote
Old 11-23-2011, 11:07 AM   #18
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

Quote:
Originally Posted by GeneSplicer View Post
Be sure to catch me - I'll be there and we can overlook catch cans. Also talk about maybe getting a MC going and talk with some of the other Miata guys there?
sorry what is an MC? I would love to meet up! Sixshooter will be there also. Is your avatar the car or should I be looking for something else?
Seefo is offline   Reply With Quote
Old 11-23-2011, 12:07 PM   #19
Senior Member
iTrader: (5)
 
Join Date: May 2011
Location: London,OH
Posts: 1,125
Total Cats: 13
Default

im going to assume Miata Club
redturbomiata is offline   Reply With Quote
Old 11-23-2011, 12:23 PM   #20
Elite Member
Thread Starter
iTrader: (5)
 
Join Date: Dec 2010
Location: Raleigh, NC
Posts: 1,970
Total Cats: 49
Default

Quote:
Originally Posted by redturbomiata View Post
im going to assume Miata Club
damn you and your obvious acronyms. I am fine with grouping up the miatas!
Seefo is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
Moroso Air Oil Separator Catch Can Aroundcorner Miata parts for sale/trade 2 10-01-2015 04:20 PM
Going back to stock. Need some 1.6 parts. Trent WTB 2 10-01-2015 01:15 PM
Leaky Wilwoods mx592 Suspension, Brakes, Drivetrain 1 10-01-2015 01:45 AM


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 02:56 PM.