What PCV system are you running on big single?

[jevansio]

I just did a quick test by hooking my boost gauge upto the dipstick hole. On idle & cruise crank pressure was around 0.2 PSI, on full boost 1.5 BAR it went upto no more than 0.5 PSI. My setup is -10 lines to catch tank which vents to atmos

[chrispot]

If your engine is good then you should get no oil mist surely?

 

If you get any oil at all in the catch can then you have engine problems id have thought, mine is always bone dry.

 

Yip, not got a drop in my catch can since I've been running it.

 

Same as mine

 

I was going to put a oil catch can on mine but there seems there is no point in doing it if they don't catch anything. I think i will do the same as Homer, leave as stock. regards chris

[jevansio]

Quick question, if I wanted to return the intake cam side back to stock, could I use one of these check valves?

 

http://www.summitracing.com/search/brand/Aeromotive/Product-Line/Aeromotive-High-Flow-One-Way-Check-Valves/?autoview=SKU

 

PS does anyone have any pics of the stock system, where it connects to, what diameter hosing etc?

Edited August 16, 2010 by jevansio (see edit history)

[jevansio]

Bumpski for pics of the stock system, where it connects to, what diameter hosing etc?

[jevansio]

Did some more investigation work today.

 

1st up I hooked up a pump my mate gave me which came off a Corolla T-Sport, can't recall exactly what it did but he said it might have been a crankcase pump or EGR related.

 

Apparently "8 in hg" is a good vaccum level to try and achive, any more and issues can arise. "8 in hg" is approx -27kpa (I'll work in kpa from now on to keep comparisons easy)

 

So with my "vent to atmos" current setup crankcase pressure is about +2kpa.

I connected the pump to the outlet of my catch tank and the pressure dropped to -10kpa. Idle remained unchanged and the pump didn't appear to be pulling any oil/oil residue when the pipes were checked after about 10 mins running. It was hard to tell if the weep from the FMS was fixed, I had quickly wiped the area clean and the was a little oil residue, but it may have run down from before.

 

Next I tried the manifold vaccum approach. I didn't use a one way valve as all testing was being done at idle. I connected a -12AN manifold fitting to a -10AN cam breather fitting with quite a large diameter hose. Fired it up again and there was a much bigger vacuum, between -50 & -60 kpa. This was obviously too much (double the recommended level). The engine didn't sound "quite" right TBH, was running well enough but I shut it down after about a minute. When I was dissassembling the pipework I noticed oil in the pipe, it had obviously been drawing oil up.

 

I put this down to the -12AN feed I had taken from the manifold, so decided to try one of the smaller nipples, a 1/4" for the dump valve. I setup the test again, this time it pulled -35kpa. Everything sounded & ran normal.

 

I then went onto an even smaller 3/16" fitting I use for a boost feed. This was around -25kpa.

 

I cleaned the fms seal area up properly and took the car for a very gentle 10 min run, pressure was constantly between -10kpa & -30kpa. When I returned there wasn't a sign of oil around the FMS area.

 

I'm defo going to put the PCV system back on the car, if anything I could do with the oil weep stopping. The car currently weeps even from the oil filler cap (there is an oily residue around that area and it's not from me filling it up), with the electric pump vacuum source attached (-10kpa) to the crankcase I had to PULL the oil filler cap to get it off

 

 

Sooooo, I got a couple of questions for those in the know:

 

1. Am I correct in assumig that if I reduce the size of the port on the manifold where I take the vacuum source, that is a good way of reducing the overall "pull" I'm applying to the crankcase?

 

2. Is there any baffle issue I have to concern myself with in the cam covers (like they've been de-baffled or something - sure I read something about the somewhere)?

 

3. Is the stock system (intake cam cover side) literally a link from the cover to the manifold with a check valve? There's nothing else I need to consider?

 

I got myself some oneway valves (taken from the brake servo of a Camry) which are the perfect size. We tested them using a 150PSI arline, and they didn't leak a jot (the braided rubber hose attached to them actually started to swell )

 

I'm happy to recieve any comment on the above as although I'm trying to return the car to it's original setup, it's only my interpretation of what is original & I don't want to make system that could lead to damage to the engine.

[Swampy442]

If you still need pics of the stock cam/intale system Ill get one in 10 mins And yes its an NRV in the cam cover to rubber hose to intake manifold. And on point 1, a restrictor will decrease the amount of suction, dependant on diameter of course.

[jevansio]

I think it's OK bud, now you've confirmed as simple as what I've done I'm happy. Many thanks mate, I guess using a smaller manifold hole is effectivly a restrictor

[Swampy442]

In the intake cam cover is the NRV

 

 

Manifold side

 

[jevansio]

That's brilliant mate

[TLicense]

Jay,

 

Looks like some good research you've been doing there. This should make it's way into the technical deposit at some point.

 

[jevansio]

Jay,

 

Looks like some good research you've been doing there. This should make it's way into the technical deposit at some point.

 

Cheers Tony.

 

I'm just pleased it "seems" to have fixed my FMS weep, also to me it looks like the stock setup (on the intake cam side) is more than enough no matter how much power you run (since it shuts on boost anyway).

 

I'm just going to vent my ex cam side to atmos for the time being, but will eventually use the exhaust as a vacuum source for that side too

[paul mac]

Sooooo, I got a couple of questions for those in the know:

 

1. Am I correct in assumig that if I reduce the size of the port on the manifold where I take the vacuum source, that is a good way of reducing the overall "pull" I'm applying to the crankcase?

 

yes this would work fine, i would copy the stock size which from memory is quite small on the pcv non return

 

2. Is there any baffle issue I have to concern myself with in the cam covers (like they've been de-baffled or something - sure I read something about the somewhere)?

 

not sure what you mean here, the stock cam covers have baffles in which to my mind would be foolish to remove as they are not a restriction to air flow and Mr T put them there for a good reason

 

3. Is the stock system (intake cam cover side) literally a link from the cover to the manifold with a check valve? There's nothing else I need to consider?

 

yes it is just a link with a check/non return valve, it is taken off a central location in the plenum, this may be so as not to "upset" any one cylinder or it may be just a packaging solution, i'm really not sure on this, however someone stuck it there for a reason so you wouldn't go far wrong if you followed this

[JamieP]

 

I'm just going to vent my ex cam side to atmos for the time being, but will eventually use the exhaust as a vacuum source for that side too

 

 

What worrys me about these exhaust vacuums is what if the check valve gets stuck shut?

[paul mac]

out of interest A.Graham-Bells book forced induction tuning has a good section on this, he quotes to not exceed 10-12 in vacuum for a street engine and also reckons Moroso vacuum pumps are pretty good http://www.moroso.com/catalog/categorydisplay.asp?catcode=17200

[jevansio]

Sooooo, I got a couple of questions for those in the know:

 

1. Am I correct in assumig that if I reduce the size of the port on the manifold where I take the vacuum source, that is a good way of reducing the overall "pull" I'm applying to the crankcase?

 

yes this would work fine, i would copy the stock size which from memory is quite small on the pcv non return

 

2. Is there any baffle issue I have to concern myself with in the cam covers (like they've been de-baffled or something - sure I read something about the somewhere)?

 

not sure what you mean here, the stock cam covers have baffles in which to my mind would be foolish to remove as they are not a restriction to air flow and Mr T put them there for a good reason

 

3. Is the stock system (intake cam cover side) literally a link from the cover to the manifold with a check valve? There's nothing else I need to consider?

 

yes it is just a link with a check/non return valve, it is taken off a central location in the plenum, this may be so as not to "upset" any one cylinder or it may be just a packaging solution, i'm really not sure on this, however someone stuck it there for a reason so you wouldn't go far wrong if you followed this

Many thanks Paul, reason I asked about the baffle was when I was drawing up oil at -60kpa, I was getting a bit worried but realsied it was prolly to do with double the vacuum than anything else. I was just after confirmation that baffles aren't removed as a matter of course when putting -10 fittings on (as I never did the work) . Mine defo have the big flat plate in.

 

What worrys me about these exhaust vacuums is what if the check valve gets stuck shut?

I know what you mean mate, I'm thinking of everything like this when trying to decide what to do on the ex side

[jevansio]

out of interest A.Graham-Bells book forced induction tuning has a good section on this, he quotes to not exceed 10-12 in vacuum for a street engine and also reckons Moroso vacuum pumps are pretty good http://www.moroso.com/catalog/categorydisplay.asp?catcode=17200

I can understand why, mine at -8 ran nice, also at around -10. At -16 it wasn't happy, sounded off and had quite a lot of oil in the pipes considering the shot time it was running

[JamieP]

 

 

I know what you mean mate, I'm thinking of everything like this when trying to decide what to do on the ex side

 

I would leave it venting to atmo, its tried and tested on many big power supras, mine has been like this for many many miles and never a problem.

[jevansio]

I would leave it venting to atmo, its tried and tested on many big power supras, mine has been like this for many many miles and never a problem.

If my oil weep stays away with vacuum just on idle/cruise I may do mate, I'm just a curious buggar & like to know if I'm missing out on any free horsepower

[jevansio]

I will also get pics of the pump I used to get the -10kpa, it was from some Toyota or other, 12v and could prolly pull a vacuum without any contamination of intake or exhaust, it was a little noisy though

[jevansio]

I have ANOTHER thought.

 

During these tests I blanked my 2nd cover breather off, this was becuase I was going to use another check valve on the ex cam side. Is this how the stock system works? If there was no check valve when the manifold side was sucking it wouldn't generate the same vacuum if it could suck infinetly through the ex side breather?

[paul mac]

I was just after confirmation that baffles aren't removed as a matter of course when putting -10 fittings on (as I never did the work) . Mine defo have the big flat plate in.

the baffles should be removed when welding the new fittings in as it uses a silicone type sealant which would melt with the heat

 

I can understand why, mine at -8 ran nice, also at around -10. At -16 it wasn't happy, sounded off and had quite a lot of oil in the pipes considering the shot time it was running

 

Dear Mr Graham Bell quotes a 3-4% power increase at 10-12in vac, to my mind yes an engine will run without but the efficiency gains are to big to ignore

[jevansio]

the baffles should be removed when welding the new fittings in as it uses a silicone type sealant which would melt with the heat

 

 

 

Dear Mr Graham Bell quotes a 3-4% power increase at 10-12in vac, to my mind yes an engine will run without but the efficiency gains are to big to ignore

This makes sense when I was reading about removing baffles for fitting big breathers, so as long as mine have the big plate back in I'm OK

[Swampy442]

Can you post some more details of this Corolla pump you have and how you installed it please Jay?

[jevansio]

Can you post some more details of this Corolla pump you have and how you installed it please Jay?

Sure I will get details today, it was only temporarily installed with a 12v car battery at the side of the car as I was only checking the idle vacuum

[Tricky-Ricky]

I have ANOTHER thought.

 

During these tests I blanked my 2nd cover breather off, this was becuase I was going to use another check valve on the ex cam side. Is this how the stock system works? If there was no check valve when the manifold side was sucking it wouldn't generate the same vacuum if it could suck infinetly through the ex side breather?

 

Jay the std system works like this, the plenum side breather, the one with the one way valve in it is the low RPM/load breather, in that it only operates when the car is not on boost, once positive boost is reached it closes, and all breathing is done through the exhaust side breather, which has no one way valve,

 

It relies on the intake vacuum from the turbos, so by blanking it off you are not seeing a realistic model of how the breather system works.

 

I am with Jamie on this leave as pretty much std, IMO you're going to be relying on either an electric motor for officiant breathing, (another device you will need to monitor to re assure yourself all is working OK) or the exhaust valves which as you say are also prone to problems! (do you need the extra worry)

 

I have to ask as before is the free BHP maybe 20 if you're very lucky, worth it?

 

Also the weeps that you are mentioning should not be occurring with the very minimal positive pressure you're seeing on you're tests, i would be looking at the condition of the seals/gasket's.

 

IMO the std system, configuration, or loosing the one way valve and blocking the plenum, using either std size pipework or upgraded size, connected to a sealed catch can and then connected to the turbo intake should provide all the vacuum needed when on boost, and should be quite adequate off boost.