Ark Posted April 27, 2007 Share Posted April 27, 2007 I'm not after bling here, I'm after a technical solution - I get crappy oily stuff squirting out of my BOV on track days, and I reckon it's blow-by oil coming out of the cam breathers. Now I know I can fit an oil catch can but there are some problems: 1: There are two cam breathers, and catch cans have two inlets. 2: With no outlet from the can, the can will be pressurised, and I reckon the breathers won't blow the crap down the pipes like that. 3: The air intake is sucking air obviously, and I reckon this helps suck the crap out of the breather pipes. 4: If the can is vented to atmosphere, we get hot, dirty, oily air venting into the engine bay, under pressure. Now if a catch can is plumbed in, inline with the cam breather and the air inlet, the volume increase upon entering the can should cause condensation of vaporised oil, plus a temporary decrease in air velocity, allowing airborne oil to drop out. Fine. But going back to point one above, cans only have two feeds...does this mean that I need two cans? Can/should the breather lines be tee'd together into one can? Is this: the "wrong" way, or only half the job? Or am I way off the mark here? Discuss. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 27, 2007 Share Posted April 27, 2007 First off, if you have a lot of oil vapor coming from your BOV i would get a compression test done;) as for catch tank, your best bet is to take the line from the left side of the cam cover (turbo side) and run this to the catch tank, and take the outlet from the tank back to the original breather hose to the intake pipe, you may want to put some metal scouring pads in the tank to help with vapor drop out;) that way you still retain the PCV system, which some people advocate, mine was open to atmosphere but now i have gone back to the set up i have just described. Quote Link to comment Share on other sites More sharing options...
Ark Posted April 27, 2007 Author Share Posted April 27, 2007 Why not catch the right side of the bay too? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 27, 2007 Share Posted April 27, 2007 You can but thats a perminat PCV breather all the time the engine is running and not on boost, it will actively extract crankcase vapor, as there is a small vacume when not boosting, when on boost the valve closes. Quote Link to comment Share on other sites More sharing options...
Ark Posted April 27, 2007 Author Share Posted April 27, 2007 Hmm, this is obviously more involved than I first thought. I read some of the other threads, and I guess it makes sense... I'm not getting _loads_ of oil coming out, and I'm talking about a 100+ miles on full boost, 8 hour track day to get this occurring, so I'm not overly worried about compression. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 27, 2007 Share Posted April 27, 2007 I never run a BOV on any modded turbo engine of mine, so that's one problem I don't have to worry about Quote Link to comment Share on other sites More sharing options...
Carl Posted April 27, 2007 Share Posted April 27, 2007 Yeah, you definately want the return pipe to the inlet filtered as the oil vapour can cause detination in extreme cases. Quote Link to comment Share on other sites More sharing options...
uzthedentist Posted April 27, 2007 Share Posted April 27, 2007 are u sure leaving scouring pads in the catch can is a good idea? i mean if you leave one of those in the sink it rusts and crumbles, surely this stuff would go back into your intake if it was in the catch can? Quote Link to comment Share on other sites More sharing options...
mr lover Posted April 27, 2007 Share Posted April 27, 2007 are u sure leaving scouring pads in the catch can is a good idea? i mean if you leave one of those in the sink it rusts and crumbles, surely this stuff would go back into your intake if it was in the catch can? use stainless steel ones Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 28, 2007 Share Posted April 28, 2007 use stainless steel ones Yep, the stainless ones that look like a load of machining swarf. I'll have to agree with Tricky Ricky about where the catch can goes as the two breather systems need to be kept seperate, and without a large amount of space in the engine bay its best to stick the catch can in the breather pipe on the turbo side. Use one with 15mm fittings as the engine breathes a lot and smaller fittings can cause pressure to build up in the crank case. You can put one on the other side (intake side) also and this would help reduce oil vapour entry into the engine, and reduce any possibility of oil contaminated intake charge causing detonation. But it won't make any difference to your oil being blown out of the BOV. Quote Link to comment Share on other sites More sharing options...
JamieP Posted April 28, 2007 Share Posted April 28, 2007 I never run a BOV on any modded turbo engine of mine, so that's one problem I don't have to worry about Are you saying they are not needed Chris? Quote Link to comment Share on other sites More sharing options...
baldy Posted April 28, 2007 Share Posted April 28, 2007 I never run a BOV on any modded turbo engine of mine, so that's one problem I don't have to worry about if i run with a bov disconnected i end up blowing boost pipes off,does this mean theres a problem with my setup? Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 28, 2007 Share Posted April 28, 2007 Yep, the stainless ones that look like a load of machining swarf. I'll have to agree with Tricky Ricky about where the catch can goes as the two breather systems need to be kept seperate, and without a large amount of space in the engine bay its best to stick the catch can in the breather pipe on the turbo side. Use one with 15mm fittings as the engine breathes a lot and smaller fittings can cause pressure to build up in the crank case. You can put one on the other side (intake side) also and this would help reduce oil vapour entry into the engine, and reduce any possibility of oil contaminated intake charge causing detonation. But it won't make any difference to your oil being blown out of the BOV. Have to point out that all the time the engine is seeing positive pressure, this valve will be closed so in theory it shouldn't have any effect on charge contamination while on boost, where it matters:) Quote Link to comment Share on other sites More sharing options...
uzthedentist Posted April 28, 2007 Share Posted April 28, 2007 ive fitted mine as below, make sure u use oil hose or braided hose though as ur silicone will corrode and go green, i used cotton overbraided oil hose with a nylon blue overbraid so it looks a bit better hoses look weird in the pic but theyre not kinked lol Quote Link to comment Share on other sites More sharing options...
Ark Posted April 28, 2007 Author Share Posted April 28, 2007 OK this gets weirder - I've got the spark plug cover off for another job at the moment, and I swear the two cam covers are piped together in two places, meaning they must breath together too. Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 28, 2007 Share Posted April 28, 2007 Thats correct, which is another reason why you don't need to use the plenum side breather, unless you are running a big single and stand a chance of generating more blow by. Quote Link to comment Share on other sites More sharing options...
dandan Posted April 28, 2007 Share Posted April 28, 2007 If you are suffering with oil vapour issues then it can get into the intake under boost regardless of the pcv. When off boost you can (via the pcv operation) find oil vapours coming into the intake plenum, by the very nature of the pcv. When back on boost this can find its way into the cyliners (or worse still one or two cylinders only). I've had several plenum chambers for modifying and seen witness of oil vapour in there from the pcv. Quote Link to comment Share on other sites More sharing options...
Kranz Posted April 29, 2007 Share Posted April 29, 2007 If you are suffering with oil vapour issues then it can get into the intake under boost regardless of the pcv. When off boost you can (via the pcv operation) find oil vapours coming into the intake plenum, by the very nature of the pcv. When back on boost this can find its way into the cyliners (or worse still one or two cylinders only). I've had several plenum chambers for modifying and seen witness of oil vapour in there from the pcv. That's true, but what kind of quantity? Can't be much puddling of oil caused by part throttle running that isn't drawn into the engine. When on boost any oil left would be very quickly dispersed. Maybe 2 catch tanks is the answer, at least to check the amount carries over by each side? Must remember though that the intake side of the PCV valve will see boost pressure, so the catch can must be capable of holding whatever boost pressure you're running plus a factor of safety (I'd suggest 2 times the boost). Quote Link to comment Share on other sites More sharing options...
dandan Posted April 29, 2007 Share Posted April 29, 2007 Personally I wouldn't bother with the pcv valve on anything much above basic bpu. I have my own breather system which I've used on many engines (highly tuned NA as well as forced induction).. however this is the big debate that crops up every 6 months or so and everyone has their own preference....... Quote Link to comment Share on other sites More sharing options...
Tricky-Ricky Posted April 29, 2007 Share Posted April 29, 2007 Must admit to being a staunch advocate of dumping the PCV system, and using catch tank vented to atmosphere, but i baulked and went to my current setup due to panic when my oil seal failed last year, and all the "experts" saying that the PCV system was paramount in preventing this;) but i/m now 99% sure that FMS problems are due to oil pressure/leakage, i may go back to my original system. Quote Link to comment Share on other sites More sharing options...
Bob Posted April 29, 2007 Share Posted April 29, 2007 Would the oil in the dump valve not be more likely caused by worn turbo seals / piston rings? I'm getting oil out of mine most of the time, but just put it down to the turbo seals. Quote Link to comment Share on other sites More sharing options...
Ark Posted August 9, 2007 Author Share Posted August 9, 2007 Just dragging this back up...again! It occurs to me that if we want the oil vapours to condense out, the catch can would be best placed where it would benefit from cooling - like in the side vent, assuming you've got an FMIC. Quote Link to comment Share on other sites More sharing options...
Ian C Posted August 9, 2007 Share Posted August 9, 2007 Oil doesn't mix with air, so it can't subsequently condense out All you need is a swirl/drop out effect to get the oil out of suspension in the air. Have the exit higher than the entrance of the catch can, and angle them so that they aren't opposite each other. Of course, if you are shifting a lot of oil then there is an underlying problem you are masking. If you aren't shifting a lot of oil, you don't need a catch can For all the information you ever need on breather systems, check out the PDF here: http://www.mkivsupra.net/vbb/showthread.php?t=46158 It's written by someone who designs them for real cars in the real world so therefore more trustworthy than all the waffle we spout -Ian Quote Link to comment Share on other sites More sharing options...
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