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View Full Version : PCV, how do turbo guys deal with this?



newaccorddriver
10-08-2006, 06:14 PM
well, im close enough to being able to get my car up and turbo next season, id just like to know how people with turbocharged accords deal with this issue. i know ill need a catch can and i already have one, but how do i plumb it in still? the valve covers easy enough to deal with, but what about the fitting on the back of the block?

bobafett
10-08-2006, 07:27 PM
hmt had a crash, but they have a really good article on pcv systems and how to do it right. :) check www.homemadeturbo.com in a little while, hopefully they will get their data back!

if i recall you just have both the valve cover and the stock pcv hose dump into a catch can. then put a filter on the top of the catch can, or somewhere T'ed into the line from the valve cover.

this allows these important functions to happen:

1 - relieve pressure from the crankcase (into the can)
2 - relieve pressure from the valve cover (into the can - ever seen high hp cars on dynos, and you can see all the smoke come out of the breather on the valve cover???)
3 - allow the valve cover to pull in clean filtered air like the way it does in a stock system.

:)

newaccorddriver
10-08-2006, 07:40 PM
hmt had a crash, but they have a really good article on pcv systems and how to do it right. :) check www.homemadeturbo.com in a little while, hopefully they will get their data back!

if i recall you just have both the valve cover and the stock pcv hose dump into a catch can. then put a filter on the top of the catch can, or somewhere T'ed into the line from the valve cover.

this allows these important functions to happen:

1 - relieve pressure from the crankcase (into the can)
2 - relieve pressure from the valve cover (into the can - ever seen high hp cars on dynos, and you can see all the smoke come out of the breather on the valve cover???)
3 - allow the valve cover to pull in clean filtered air like the way it does in a stock system.

:)

ive read that article that was somewhat well written on HMT, but wiithout pictures, the words mean nothing to me really. he says to not put the crank case under vacuum and a bunch of other stuff, and im just sitting there thinking.

i was thinking of 'T'ing the valve cover and the back of the block into one, and send it straight to the catch can. that would take up one of the 2 holes on the catch can. the remaining hole on the catch can would go into the pre-turbo pipe and there would be a vacuum. im not sure if this would work or not, but id like to know if it does, cause if it doesnt, it would save me a headache

bobafett
10-09-2006, 07:07 AM
what pre turbo pipe? if you put a breather on the other hole of the catch can that will allow the vacuum it needs. :)

newaccorddriver
10-09-2006, 08:25 AM
what pre turbo pipe? if you put a breather on the other hole of the catch can that will allow the vacuum it needs. :)


wouldnt it spit out oil through the breather filter like that?

i always thought the 2 pipes had to be under constant vacuum as theres always a vacuum source there when its connected to the intake/manifold.

as for the pre turbo pipe, i meant putting it just after the air filter, and before the turbo. plenty of vacuum there and its constant, just like how it would normally be since the hole on the back of the block is connected straight into the intake manifold

bobafett
10-09-2006, 09:02 AM
oh ok i see what you're saying.

the breather 'could' spit oil, but generally the only pressure that comes out of the crankcase is what gets past the rings. so it shouldn't be a whole heck of a lot.

the pcv valve keeps vacuum from pulling into the crankcase. its just a one way valve that only allows the oily air to escape the crankcase when air that gets past the rings needs to escape.

so thats the PCV part of the system. but the valve cover also gets fresh air, and has is a source of vacuum. if you take off that hose you will notice vacuum sucking into that port. so as long as you have a breather somewhere that allows the valve cover to get filtered air, you are ok. but in a boosted situation maybe its feasable that it could spit oil out...

so the solution is to put both the valve cover line, and the crank case line (after the pcv filter) to both be routed to the catch can. additionally you should have a breather on the top of the can (or get it away from the places where oil will end up draining into the can. also, some people use things like scotch pads to help seperate the oil from the air and allow the 'filtered' air to be cleaner. :)

is this clearing anything up or just confusing you? it sounds to me like you just need to add a breather to either your catch can, or just install one somewhere on the valve cover line as it is heading to the catch can. either method will accomplish the same thing.

A20A1
10-09-2006, 09:58 AM
You can get a belt driven vacuum pump, or a exhaust vacuum valve, simmilar to the Air Suction valve if you want another vacuum source.

87preludeA20A3
10-09-2006, 06:32 PM
Ok one, question, is a catch can necessary? I understand the concept and all but do you need it?

TWOLOUDNPROUD
10-09-2006, 07:18 PM
Ok one, question, is a catch can necessary? I understand the concept and all but do you need it?
yes it catches the oil and stops the oil from being sucked in by the intake of the turbo.

gfrg88
10-09-2006, 07:24 PM
my car spits oil through the valve cover breather, should i get one :dunno:

TWOLOUDNPROUD
10-09-2006, 07:32 PM
my car spits oil through the valve cover breather, should i get one :dunno:
Are you turbo ? if not and it spiting oil through the valve cover you might need a oil change your oil or need a thicker oil or you rings are wore to piss and you have a lot of blow by you pick which one it may be.

TWOLOUDNPROUD
10-09-2006, 07:32 PM
Sorry it double posted

shepherd79
10-09-2006, 07:39 PM
my car spits oil through the valve cover breather, should i get one :dunno:

if you don't have turbo, you need to fix the problem.
most likely you need to replace PCV valve.

AccordEpicenter
10-09-2006, 07:46 PM
i just have a breather to vent it. The problem with having the pcv vapors hooked up to the intake of the turbo or the intake manifold is that the vapors severly lower the octane of the incoming air/fuel charge and promote detonation. So id avoid it.

newaccorddriver
10-09-2006, 09:00 PM
is this clearing anything up or just confusing you? it sounds to me like you just need to add a breather to either your catch can, or just install one somewhere on the valve cover line as it is heading to the catch can. either method will accomplish the same thing.


im sonewhat getting it, yet im somewhat confused at the same time... ill get it in time though...


are you saying, the fitting at the back of the block is the actual PCV valve and that needs to be vented in somewhere, and the valve covers port is the one that draws in the fresh air so it recirculates(in an odd way)?

AccordEpicenter
10-09-2006, 09:03 PM
they both need to be on a breather

newaccorddriver
10-09-2006, 09:13 PM
they both need to be on a breather

kinda like this HMT shit?

so would i be able to 'T' off both those lines and send it to the catch can with a breather on it?

http://i56.photobucket.com/albums/g186/Newlser/Picture124.jpg

87preludeA20A3
10-09-2006, 09:38 PM
Well i get how the catch can works but... accordepicenter you are turbo right? And your saying you don't use one... For the valve cover i just have a breather and i have the pcv valve line hooked into the intake mani like stock. Will the turbo force more air around into the engine hence more oil will be flying around and getting past the pcv and getting into intake air.????

AccordEpicenter
10-09-2006, 09:39 PM
yes that will work, i would hook one line of that to the valve cover port and the other to the pcv port. Job done

Edit: I just had them both on a breather, i didnt have a catch can. The turbo will probably encourage more blowby into the block and push vapors into the intake air more...

newaccorddriver
10-09-2006, 09:49 PM
out opf curiosity, isnt the stock setup supposed to keep tjhe crankcase under vacuum the entire time?

if thats the case, wouldnt it be easier to send both lines through the catch can, and then send a line from the catch can to the preturbo intake? that would keep everything under vacuum atleast rather then the setup below which looks like it would lead to a neutral state(no vacuum or boost except for whatever the crankcase blows out)

AccordEpicenter
10-09-2006, 10:14 PM
yes, except that the engine sucking in its own vapors can cause detonation, which is bad on a forced induction motor

bobafett
10-09-2006, 10:24 PM
yeah the stock line is setup to pull the oily shitty air right back into the intake manifold to get reburned. thats one of the reasons our intakes look like shit when we take them off. but like they mentioned above, it lowers the effective octane rating of your fuel. so your premium isnt really premium by the time the engine sees it.

on the other had when you are WOT you are not generating vacuum, so it won't be sucking the air out of the crankcase. but if you are getting blowby, that air might still be pushing its way past the pcv and into your intake. :(

TWOLOUDNPROUD
10-09-2006, 11:24 PM
This one for Mkymonkey........sea foam http://img.photobucket.com/albums/v447/koreanwilcox1/Catch%20Can/CatchCan014resized.jpg

TWOLOUDNPROUD
10-09-2006, 11:33 PM
Here how Rob did it ...................http://www.beesandgoats.com/boostfaq/PCV_turbo_2fit.jpg

newaccorddriver
10-10-2006, 02:17 PM
Here how Rob did it ...................http://www.beesandgoats.com/boostfaq/PCV_turbo_2fit.jpg


this is exactly how i had it in mind, but shouldnt i use 2 catch cans? one for the PCV and one for the valve cover. i dont really see how the engine would be able to suck up any oil, but i really dont know how a catch can 'catches' oil. mines just got 2 holes and thats it. i see the air going in one way and out the other, how exactly does it catch any oil?

AccordEpicenter
10-10-2006, 02:36 PM
you guys are on HMT too?

newaccorddriver
10-10-2006, 05:27 PM
you guys are on HMT too?


im A20A3T if you havent realized:welcome:

AccordEpicenter
10-10-2006, 05:46 PM
yeah i figured you, but TWOLOUDNPROUD?

87preludeA20A3
10-10-2006, 08:09 PM
Accordepicenter you answered my question thanks.. I would just rather not deal with the can crap. Maybe later but not now

89T
10-17-2006, 03:40 PM
heres a link for a simular option.
http://www.theoldone.com/components/breather/

rjudgey
10-17-2006, 11:28 PM
If you can get away with ditching the PCV system your engine will be better for it. Mine are clena as new everytime i pull it apart with no PCV system. The only thing you ahve to remember to do when removing is to put a breather on the rocker cover, and then you ahve to mod the PCV catch tank so that you can fit a breather on top which means removing the PCV valve in the top of the can so that it will breathe or what i did was drill six holes in the top of the can and just left it at that. Only issue is if you drive through a big puddle or if it's really really wet you might get some water in through the top unlikely but you never now so breather on top through a hollowed out PCV valve is often better. Mines mainly race so i just not really bothered plus with my extra holes the engine can breathe better than trying to go through a tiny narrow valve and filter. If you leave the PCV catch tank and valve alone and just put a rocker cover rbeather on you'll find that you'll get a shed load of oily smoke coming out the top breather as the engine is then trying to force all it's internal gases out of that one hole relieving the block as well helps stop this but you will notice when driving that your cockpit will stink a little bit of oil and petrol. If you ahve a sensitive nose then another option is to rig up some vacuum pipes to the rocker and the PCV catch tank, then join both toger onto a pump then suck the old stuff out and run the pipe to the underneath of the engine bay and out of the way of the cockpit intake, or the other option is to run it into the exhaust where the oil will get vapourized by the hot gases coming out but this will put up emissions so not recommended, the other great thing about the air pump option is if you get a big enough pump it will create a vacuum inside the engine which will keep it cleaning and stop any corrosion but will also cause less friction to the rotational parts as there is no air to create friction with might only be worth .5 to 1bhp but hey every little counts!! Just shame the extra weight will offset the benefit!! But not having the oily air to burn with your nice clean air and fuel will make more power anyway and were talking a few bhp difference which will help a lot more.