fryup Posted May 27, 2012 Share Posted May 27, 2012 Interesting read so far! My setup (13B turbo) has the two vent tubes from the filler neck connected to a vented catch can with no drain. This works fine until the catch can fills up and the engine starts blowing smoke. Just have to remember to tip the can out every 6 months or so and its sweet! Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted May 27, 2012 Author Share Posted May 27, 2012 what sort of boost are you running? Yep- I see why a vacuum will help purge the sump of vapors and oil mist, which over time the petrol element would contaminate the oil. But if those vents are not connected to a vacuum i still dont see there being huge pressure build up. The vent holes are 7mm ID- two of them. The pressure buildup is just what ever gets past the oil control rings and i think an engine is getting heaps of oil/gas past them i think there are further issues that need be addressed eh. In fact- perhaps a little build up of pressure in the sump as opposed to a constant vacuum may well help a tired engine by hindering the gases from wanting to sneak by?... Quote Link to comment Share on other sites More sharing options...
fryup Posted May 27, 2012 Share Posted May 27, 2012 Yea I don't think there is a huge pressure build up at all, like you say. I'm only running 8psi at the moment. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted May 28, 2012 Share Posted May 28, 2012 Did you mean to say the vent hoses were 7mm I/D? That is tiny! I used two 16mm I/D hoses on my old 1600cc piston race engine (before I went to dry sump), and any less was a problem (it did have a fairly small sump though which made it prone to blowing out oil) Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted May 28, 2012 Author Share Posted May 28, 2012 oh yeah- all my old piston cars have had huge vent holes/fittings/hoses. But..? rotaries have far less pressure rising in the sump from lack of pistons squishing up and down?...(i think...) Thats the size they have been since Kenichi first had a glint in his eye. Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted May 28, 2012 Author Share Posted May 28, 2012 This is how it is now... This is a common catch tank setup I think. Not assisted in anyway by vacuum. Maybe it works fine due to hot gases wanting to rise up? And this setup would use the vacuum from inlet before turbo. it will work but could still possibly upset settings on mixture going into engine... (excuse the photo being on its side..trying to sort it out but I think the satellite got hit a by strong wind when the photo went through) This one here wont upset settings so much I guess as its using vacuum before carb. but when throttle is shut its not sucking so much? But I figure there isn't so much blowby at idle and therefore not many vapors created. This setup should promote more purging of old vapors with fresh air by sucking clean air into the sump through a small filter and so expelling build ups. Would also leanout the vapors out for cleaner burning??? But if routed after carb will be more likely to upset the mixture as essentially a vacuum leak... And here, using the exhaust to create the vacuum assist, a system that is totally separate to the induction side of the engine. But I still wonder how much suction can be attained with a small tube stuck into the exhaust pipe. Especially as the exhaust system, when the car is at full boost, is full of hot expanding gases. They would try and close any one way valve needed in this system and right when the sump is getting full of pressure itself from blow by. Quote Link to comment Share on other sites More sharing options...
durty Posted May 28, 2012 Share Posted May 28, 2012 Can't help at all but awesome pictures alex Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted May 28, 2012 Author Share Posted May 28, 2012 You like my turbo vanes that look like flowers.. Quote Link to comment Share on other sites More sharing options...
slacker.cam Posted May 28, 2012 Share Posted May 28, 2012 I guess there are also two variations on the basic catch can setup (2nd to top pic). You could run it with the centre plate vent blocked or open. What did you have in mind if you are to go down this path? On a piston engine you generally have no vent aside from the one that goes to the catch can. I would suggest that in this case it's the same deal. Or you could also run that point into your catch can also. What option are you leaning towards? Quote Link to comment Share on other sites More sharing options...
slacker.cam Posted May 28, 2012 Share Posted May 28, 2012 I'm not sure if this will help your situation at all but here are some diagrams from SR20DETs. Posting these purely because these are a turbo engine that I'm familiar with and it may be of interest to you. So these diagrams show the factory breather setup on SR20DETs, they both show the same thing in a slightly different way. They have two different paths for the gasses depending on if the system is in vacuum or in boost. It's pretty nifty. See this link for a pretty good writeup on your catch can option for these motors. It might give you some inspiration Quote Link to comment Share on other sites More sharing options...
Unclejake Posted May 29, 2012 Share Posted May 29, 2012 Your other alternative is to plumb the factory vents into the air filter rather than the inlet manifold. Is the system you currently have how the factory designed it for a turbo application? If so then I am missing something as I can't see how it would work Quote Link to comment Share on other sites More sharing options...
Spencer Posted May 29, 2012 Share Posted May 29, 2012 THose diagrams of factory turbo cars are pretty much how a normal PCV system is hooked up on most factory NA engines also. The PCV valve wont let boost back into the crackcase and in this condition blow by is vented back into the intake before the throttle plate, this is the same as what happens under full throttle in a NA engine. But at cruise speeds etc where the car shouldn't be on boost it will be open and have full manifold vaccum to suck through clean air through the crankcase. This is pretty much how I would set up any car turbo or not, unless you have oil spitting issues then you could plumb a catch can into a factory style system if you put it in the right place Its funny that PCV system is so often the cause of confusion and internet battles (ala forced). Its pretty much the first thing I check and fix on old cars its usally blocked or stuck open and making the car run like arse Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted May 29, 2012 Author Share Posted May 29, 2012 Cheers for pics. The one I am leaning towards is either diagram 4 but suck it into the filter. 4 would be best as I'll properly be purging the sump area with fresh air all the time. Maybe I could add a drain back to the sump but I don't think I'll be filling the tank up that quickly. The current system is how the The elford came setup except the other vent in the centre plate would have been connected to something. I can't remember quite where. It's not ideal that's for sure hence why I want to change it. The pcv valve is the stock Mazda one. Even though I don't think there is too much oil being lost I do want to avoid sucking any oil through the induction system and so have it burning inside leaving carbon deposits. I want to avoid any deposits building up as its a high comp engine with a turbo and I don't want any pre-ignition ( Im still looking for a 12a turbo dizzy with its boost related retard feature) Quote Link to comment Share on other sites More sharing options...
Spencer Posted May 29, 2012 Share Posted May 29, 2012 Pretty sure the setup you have now is just like a factory PCV system accept the block vent should feed infront of the carb. Just make sure you have a working PCV and its the right way, it should give you no trouble and it shouldnt eat naff all oil Quote Link to comment Share on other sites More sharing options...
yoeddynz Posted May 29, 2012 Author Share Posted May 29, 2012 Yeah I think it was probably routed into the old style air filter. Quote Link to comment Share on other sites More sharing options...
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