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| Oil Catch Can | |
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| Tweet Topic Started: Jun 24 2012, 09:27 PM (6,157 Views) | |
| Higgsy | Jul 2 2012, 02:56 PM Post #26 |
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![]() from what i can see with glenns (Celica RA45) he hasnt. the 2 red tubes both run into a catch can. thats why im confused i think. there seems to be more than one way of doing it. |
| from a beams ITB to a 2JZ | |
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| Tezz-Winnie | Jul 2 2012, 02:58 PM Post #27 |
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Also if you dont plumb it back into your manifold somewhere the PCV system wont work as efficiently as the fast moving gas in your manifold actually pulls the air out of the crank case. Hard to explain why this happens took me ages to get my head around the concept when I was doing my trade in the Airforce but think of it like getting sucked into a fast moving train on a platform or how when your windows are down, loose objects seemed to get sucked out of the window. The more vacuume on this hose the eaisier it is for your crank to vent. |
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| Higgsy | Jul 2 2012, 03:00 PM Post #28 |
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YUSS!!! i love when people dumb stuff down. i get it!! |
| from a beams ITB to a 2JZ | |
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| Tezz-Winnie | Jul 2 2012, 03:09 PM Post #29 |
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Yea there is definetly a heap of different ways you can configure a catch can. you can dual filter, vent to atmosphere, mix of the two. Generaly it all depends on the motor and the PCV system it uses. There is no reason to run your breather into a catch can though unless your local regs wont let you get away with a atmospheric breather (AUS FDA laws def require your breather to rout back to you intake but its easy to fake and cops dont know the difference and is rarely picked up in the pits) The PCV valve is the most important though and needs to be routed as follows. PCV valve to catch can to manifold (or after the butterfly valve) and the ENTIRE system needs to be airtight with no leaks. |
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| Higgsy | Jul 2 2012, 03:13 PM Post #30 |
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wicked, aprreciate the help and patience. will look into drilling and tapping my new adaptor plate to sneak it in there. **damn, that wont work, unless going into 1 cylinder is ok?**
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| from a beams ITB to a 2JZ | |
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| Tezz-Winnie | Jul 2 2012, 03:15 PM Post #31 |
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Something else to keep in mind is if your can ever gets full and you dont realise it you will blow your cam cover gasket (rocker cover for those who think you have rockers!) quicker then anything and ive seen it happen quite a bit. so make sure you mount it some where that you can easily see the fill gauge (the tube running from the bottom to the top) and the empty valve (if its fitted) remains CLOSED |
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| Tezz-Winnie | Jul 2 2012, 03:20 PM Post #32 |
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Have a look at the RB26 ITB's to see if each TB has a fitting for the PCV system. The only reason you need to do it after the TB is so it doesnt coat the TPS with oil vapour. IF you have a catch setup it wont matter and surely you could just put it somewhere after your MAF... |
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| Higgsy | Jul 2 2012, 04:03 PM Post #33 |
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i cant find out much about the rb26 itbs, but cant see tubing going into each seperate intake and if thats the case i could just run it into the pretty new plenum i have coming.
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| from a beams ITB to a 2JZ | |
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| Tezz-Winnie | Jul 2 2012, 04:29 PM Post #34 |
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Wasnt sure but It wouldnt matter anyway because the oil is removed from your blow by and wont coat your TPS. Just make sure you mount the fitting on the narrowest part of the INTAKE of the plenum and def not on the individual runners themselves (unless you want to put a fitting on each and every one of them) as this is where the air will be running the fastest and therefore have the most vacuum (this is the logic I struggled to come to terms with lol). Its known as the Venturi effect. |
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| Higgsy | Jul 2 2012, 04:35 PM Post #35 |
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i found this really interesting with the plenum design stuff http://horsepowercalculators.net/intake-ma...manifold-design and it clearly shows the fast moving sections etc at the very bottom. |
| from a beams ITB to a 2JZ | |
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| Tezz-Winnie | Jul 2 2012, 05:00 PM Post #36 |
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Yep exactly where I told you to put it lol. "Just make sure you mount the fitting on the narrowest part of the INTAKE of the plenum and def not on the individual runners themselves " (Keep in mind im talking about the plenum itself which is defined as the large chamber the runners attach too....) Got no idea why anyone would put the fitting on the runners but just thought if someone wanted to they should know you cant just dump all your blow by into one cylinder. |
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| Celica RA45 | Jul 2 2012, 05:29 PM Post #37 |
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the pvc is designed to suck out the oil and petrol fumes straight into the plenum which does contaminate your air fuel ratio by changing it 2 a catch can 1 it doesnt effect the air fuel ratio and 2 it still lets the fresh air in if you look at mine 1 is further down in the tank and the other is close at the top near the big hole so it sucks in fresh air |
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| Tezz-Winnie | Jul 2 2012, 05:43 PM Post #38 |
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The catch can is designed to filter the air though so it can be returned back into the loop, for a racing application its complexly different because certain FDA regs don't apply to track cars... If you remove the ability of the plenum to suck the gasses out of your crankcase you reduce the efficiency of the PCV system and instead the crank case has to push air out through the filter (if your using one) and then will just use the breather anyway. |
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| Celica RA45 | Jul 2 2012, 07:47 PM Post #39 |
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when the trd kit came out they block up the pvc valve hole all to gether and just use the fresh air vent i changed that set up to my set up and it runs fine i empty mine out every 3 months with only 20mm of water vapour in the bottom |
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| Higgsy | Jul 2 2012, 08:32 PM Post #40 |
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hey glenn, would it be too much to ask for an engine bay picture of that setup you have? |
| from a beams ITB to a 2JZ | |
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| Celica RA45 | Jul 2 2012, 10:20 PM Post #41 |
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give me a day or 2 and will put it up or have a look at toyspeed in members projects also the pvc wont work on full throttle as there is no vacuum higher in the rev range |
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| Tezz-Winnie | Jul 2 2012, 11:33 PM Post #42 |
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Completely incorrect. Your a smart dude and you know your shit but fluid dynamics says otherwise. If that was true then all the blokes that designed factory turbo pcv systems should rip up their degrees... The only reason pcv systems don't work at verry high rpm is because the valve itself becomes to much of a restriction to efficiently vent crankcase blowby which is why you have a breather hose. |
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| yojimbo | Jul 3 2012, 12:37 AM Post #43 |
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^^ lol. Race engines don't recirculate crank case vapors (except maybe Subaru boxer engines cos they are a dumb idea anyway). it is purely an emission control measure. |
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| Tezz-Winnie | Jul 3 2012, 10:58 AM Post #44 |
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I was talking about factory turbo charged engines for street use... On the track however I think you will find scrutineers are pretty harsh on PCV breather systems to make sure they are correctly filtered and set up as they dont want oil all over their track... PCV systems are vital for any engine. As soon as the crank case builds pressure you have resistance pushing on the bottom of the piston pushing oil up through to the combustion chamber thats why it recirculates to the cam cover but if your cam cover cant breath it will find a way to breath and this usually results in a blown cam cover gasket 99% of the time. But then you say why dont you just let the cam caver breath to atmosphere? Wrong because then you draw water vapour into your cam cover when you lift your foot off throttle and this is where you need clean dry air to come into your engine. Some race engines have very exotic ventilation systems from using a myriad of check valves and routing blowby to your exhaust to using an external electric pump with more check valves ect... Simplest solution for a street car is to just rout your PCV valve into a catch can and use the venturi effect created in your plenum to such the gasses out. The remaining blowby would be nothing but a bit of unbrunt fuel and exhaust. (A hell of alot more then what is dumped in there by your EGR system!) |
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| peanut | Jul 3 2012, 11:10 AM Post #45 |
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every thread with you two in it always put a smile on my face ![]() What winston said reminded me of my mate whom i use to track with. he does loads of backyard DIY to her cerfiro. so he made up a catch can. it overflowed and host came lose, oil+fuel bursted out and left a trail of fire on the track. lucky his car didn't catch on fire as he was just at the pitwall so 10 guys ran out with extinguisher to put the fire out. |
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| 4ga | Jul 3 2012, 12:24 PM Post #46 |
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PCV works by circulating air through the crank case, gas is sucked out of the cc through the PCV valve by engine vacuum (ie connected to plenum) the gas enters the cc via blow-by and also through the breather (metered air from the intake tapped off between the maf and throttle so wont mess with A/F ratio). The PCV valve is there to regulate the amount of gas recirculated for different load/vacuum. The entire system works based on the presure differential that exists on either side of the throttle body due to engine vacuum. This wont work so well when you no longer have a tb lol. It is woth noting at high load that the blow-by gas' may excede the capacity of the pcv valve and also flow back out the breather, in either case these gas' are recycled back into the intake. The PCV system serves two functions the obvious one is emissions control, hydrocarbon rich blow-by gas is recyled into intake. The second is the removal of water vapor from the cc which if left will contribute to oil sludging and shorten oil life. In your situation think can go either way: Setup like RA45, remove pcv valve and connect both breather and pcv to catch can, have the can vent to atmosphere (usually through a small filter). This will rely on the positive preasue in cc from blow-by to force gas' out through the two vents. Seems the most common way, wont get fresh air through the cc and not the best for the environment (think of the children )Setup like TW propose, relly on venturi effect to scavenge gas' out of cc and create air flow from breather. Cant say I have seen it before but think it should work, this would be closest to the stock system. I would question if there would be enough vacuum created to operate the PCV valve so think may want to remove it. There is one other option, could use a vacuum manifold like in the celica build thread, I would only really consider this if you also needed it for map based engine management. |
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| Tezz-Winnie | Jul 3 2012, 01:16 PM Post #47 |
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Dont remove the PCV valve. .. As long as the crank case pressure is higher then the pressure of the manifold it will work its just more efficient behind the throttle bodies thats all. |
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| Celica RA45 | Jul 3 2012, 06:14 PM Post #48 |
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thats all good, but the quad inlet doesnt have any provision for the pvc valve to attach .not the same set up as a 2tg carbie motor that had spacers with a air gap and pvc coming from block also thats why the top oil drain vent is there as well from the back of the head to the bottom of block |
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| Tezz-Winnie | Jul 3 2012, 06:50 PM Post #49 |
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Thats why I suggested to put it just before the plenum (plenum inlet) where the air is flowing the highest to create a venturi vacuum that will suck the blowby out of the crank case. The only difference is instead of having a vacuum off throttle it would see atmosphere which would still be higher then the crank case pressure. Obviously it would be stupid to do this for a turbo setup because as when you come off throttle it would slam your PCV valve shut and damage it within a few hours. Other option is to vent to atmosphere and fail an emission test or you could rig up an pcv exhaust scavenging system like real race cars use and once again fail an emission test... |
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| Tezz-Winnie | Jul 3 2012, 06:56 PM Post #50 |
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At the end of the day the amount of blowby getting into your combustion chamber is too small to have detrimental impact on performance. INFACT if should cool combustion chamber temperatures just as your EGR system does.... Most blowby is unburnt fuel, exhaust, water vapour and oil vapour (NOT liquid oil if this is happening your doing it wrong) and nitrogen oxide which is a very good oxidiser anyway. By removing the oil vapour with a condenser catch can set up all you have left over is the good stuff plus a little bit of water and exhaust. Obviously the best solution is to use a scavenger system but your hurting the environment really arent you... |
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