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1FSTBRD
09-22-2015, 04:22 PM
With head gasket failures being as common as they are on these cars, I was wondering if the PCV system contributes to that. I'm not a huge expert on PCVs, but from what I know, their function is to vent the crankcase of too much pressure/ blowby, and also to reduce emissions, but one thing I had noticed on my 3.8 Mustang is that the upper and lower intake manifolds (and the runners going into the head) were just absolutely caked with sludgy, oily residue. This can't be a good thing in terms of air quality, because before I cleaned my intakes out in the 'Stang, I was getting more pinging, and higher octane wasn't solving it. It was driving me nuts. The factory PCV seems to be way too aggressive.

I don't have the experience of dismantling the SC engines like other people have, and the most I've done was take off the intake plenum/ supercharger/ intercooler/ IC tubing. But even after cleaning those things out, after taking them off again even a couple of weeks later, I'd noticed that the supercharger top and intercooler once again had a fair bit of oil in them. One wonders how much the oil and blowby reduces the effectiveness of the octane, especially under boost. What have people noticed with the lower intake and the ports going into the heads--do they get a fair bit oiled up with sludge? The intercooler seems to act as a bit of a filter (based on the oil that puddles up in the bottom), and the return plenum and return plenum area going into the intake manifold appeared to have a little bit of oil residue built up, but nothing major. The Mustang's intakes had a black tar, basically in them.

I had put an M/E Wagner dual adjustable PCV valve on the Mustang, along with an air/ oil separator, and after opening the intake back up, the system was almost totally clean (minus some black soot from the EGR valve). The PCV is pretty much disabled at WOT, but I still wonder if under cruise conditions and light boost, whether the PCV is pulling too much (too much blowby, reducing the octane level) or whether there's enough vacuum through to relieve the crankcase pressure enough under light boost (5-8 psi boost) when giving the car a little more acceleration, but still not wide open throttle and full boost. I'm kind of wondering if the factory PCV wasn't engineered for an N/A car, instead of a boosted car.

Thoughts?

KMT
09-22-2015, 05:46 PM
I've stocked up on what I think are appropriate items - see: http://www.sccoa.com/forums/showthread.php?131930-how-much-boost-will-an-after-market-pcv-valve-leak&highlight=pCV

1FSTBRD
09-22-2015, 09:25 PM
I never thought of a boost leak.....that totally makes sense! You have some of the best responses on here--what's your name, by the way? My actual name is Ryan.

Next year, i'll be getting a Quarterhorse and BE, and i'd like to measure some boost/ vacuum under various PCV adjustments. I'm not affiliated with them in any way, but i've mentioned the M/E Wagner dual adjustable PCV and feel it is a highly underrated piece of gear, because it finally allows people to specifically dial in an idle circuit and a cruise circuit, instead of having to try a bunch of PCVs and find if it's drawing too much or too little vacuum. It's a bit expensive, but it's also very well built and engineered. There's precise check balls in each of the circuits.

I think I may temporarily take it off of the Mustang and see how the SC changes with a different PCV tune. Any advice or recommendations on how aggressive to set it? Another interesting thing is that you can completely close the cruise circuit (PCV doesn't draw vacuum), and the PCV would only be open during idle. Would that be a certain way to make sure that no boost is getting by the PCV? That would be a track only type of thing, I guess, since the crankcase isn't being vented, but if I'm calculating it correctly, one would at least have the piece of mind knowing that the PCV is closed under boost?

KMT
09-22-2015, 09:32 PM
Hey, Ryan - nice to meet you - Ken.

I'm not sure we can prohibit all boost leaks, but if the alternative is wasted boost, I'm going to try to reduce as best I can. I've looked at other factory boosted Fords for parts ideas, but nothing's jumped out at me yet. The most luck I've had is by simply testing the valve by mouth to see if it fails to seal at all to know which don't deserve to go under my SC's hood to begin with.

nmcbchief
09-22-2015, 09:37 PM
Headgasket failures on our cars are due to detonation more than anything! Running too low of octane fuel, too much boost(overdrive) are 2 of the major factors to headgasket failures.

1FSTBRD
09-22-2015, 09:50 PM
Hey, Ryan - nice to meet you - Ken.

I'm not sure we can prohibit all boost leaks, but if the alternative is wasted boost, I'm going to try to reduce as best I can. I've looked at other factory boosted Fords for parts ideas, but nothing's jumped out at me yet. The most luck I've had is by simply testing the valve by mouth to see if it fails to seal at all to know which don't deserve to go under my SC's hood to begin with.

Nice to meet 'ya, as well, Ken! Good to know some more people's names around here.

Would sealing around the PCV grommet (the top area) with RTV help to reduce boost leaks? One would think it would. I'm just trying to figure out small ways to build power, in amongst the bigger ones.

1FSTBRD
09-22-2015, 09:57 PM
Thought I'd post a link to the adjustable PCV:

http://mewagner.com/?page_id=444

KMT
09-22-2015, 10:55 PM
Would sealing around the PCV grommet (the top area) with RTV help to reduce boost leaks? One would think it would. I'm just trying to figure out small ways to build power, in amongst the bigger ones.

I just rely on a fresh grommet (low cost and readily available, so no excuse to not replace on a regular basis, I think), and then watch for any evidence of leaks, such as oil stains, etc. When I installed a pair of vapor traps, the first plastic hose I used to extend the plumbing couldn't take the heat and cracked, and leaks were pretty easy to spot. Once I found the proper materials, I used silicone adhesive on them during heat gun assembly. with a few clamps at the joints and it's been over two years now with no visible leaks on the PCV system.

racecougar
09-23-2015, 07:19 AM
It's been some time since I've stared at a stock setup, but doesn't the line from the PCV valve connect to the inlet plenum (between the throttle body and supercharger)? That negates any chance of a boost leak.

rzimmerl
09-23-2015, 07:36 AM
It's been some time since I've stared at a stock setup, but doesn't the line from the PCV valve connect to the inlet plenum (between the throttle body and supercharger)? That negates any chance of a boost leak.

Yes it does. Best PCV related thing to do on an SC is install a PCV separator system to keep the sludge from building up and degrading the combustion process.

KMT
09-23-2015, 09:59 AM
It's been some time since I've stared at a stock setup, but doesn't the line from the PCV valve connect to the inlet plenum (between the throttle body and supercharger)?

Now that you mention it, I don't see how that line could see boost under normal circumstances...maybe if the crankcase was being pressurized.

64137

1FSTBRD
09-23-2015, 12:58 PM
Some good ideas and theories being mentioned here. Do you guys know if the intake plenum sees much pressure in the form of air resources that don't fully get taken in by the supercharger? I suppose one could hook a vacuum/ psi gauge up to one of the vacuum lines on the intake, maybe put a tee on the PCV line and see what the reading is, just revving the car a bit at idle. The system would be under boost, but what reading should you see in the actual intake plenum under preferable/ normal conditions? I would tend to think that the pressure (any vacuum resources?) could tell you how much restriction (or pressure--air rejection by the blower?) would be in the system, both at lower boost psi and higher psi. Feel free to correct this if it's wrong.

One thing that I've always wondered is how much error factor there is in the valve/ butterfly that closes off the N/A power so that the engine only sees boost, and how much (if any) air escapes past it under boost conditions. Another thing that I was thinking, is whether there's a way to make that valve close off quicker so that the engine sees boost quicker, or whether that would mess with the timing of the car or would create other longevity problems.

racecougar
09-23-2015, 07:27 PM
You'll see vacuum at the inlet plenum, not boost, hence the reason for tapping into it for all vacuum-only needs (such as the PCV). Boost-referenced items (such as FPR) tap into the return plenum. Like Ryan said, if you want to reduce the amount of oil entering your inlet tract, install a quality oil separator.

http://i6.photobucket.com/albums/y207/racecougar/90%20XR7/new%20engine/th_oilseperatoropen.jpg (http://s6.photobucket.com/user/racecougar/media/90%20XR7/new%20engine/oilseperatoropen.jpg.html)

1FSTBRD
09-23-2015, 09:31 PM
Another way that some consider a PCV is a controlled vacuum leak, which, in terms of something a bit more understandable, makes sense. With the adjustable PCV valve on the Mustang, I had made it draw much more vacuum at cruise speeds to test it out, and the ECU must have been reading it as, essentially, a much bigger vacuum leak. When I made the cruise circuit more restricted (tightened the screw in), I could hear the engine ingesting air at a higher pitch at about 1800 ish rpm, whereas before, it would do it at about 2200-2300 or so. The car felt sluggish at WOT right after the PCV was closed a bit more, but after it had a chance to re-calibrate the air/ fuel along with the proper vacuum, it felt like a totally different vehicle.

I'm wondering if the SC's stock vacuum (especially as intakes, heads, etc are changed) doesn't have an incorrect a/f with the PCV being too aggressive at cruise speeds, which the ECU then applies to the overall a/f curve/ ratio, at WOT. It just kind of bugs me that oil gets in the supercharger, because that would tend to signify that if the system is drawing way too much oil through the system, that there's way too much vacuum being drained. If the PCV is disabled at WOT, then the oil shouldn't be going through the system. At some point, I think that the ECU gets used to all the hot oil and blowby and it either pulls timing or has additional detonation/ lowered octane consequences.

Edit: i'm still learning how the SC's PCV works. I had read elsewhere on this site that the tube from the valve cover on the driver's side is a boost only, PCV shut tube. If this is the case, that would explain why it gets so oily. Would it be a good idea to run two air/ oil separators, with one on each valve cover? It would explain why the throttle body plate gets an oily residue on it and why the supercharger and intercooler get so much oil in them. Has anyone here (or in the past) run air/ oil separators on both valve covers?

racecougar
09-23-2015, 10:24 PM
While PCV air does bypass the throttle blades, it does not bypass the MAF. It's accounted for with regard to fueling. Where you'll run into trouble is if you open one side to atmosphere (installing a breather on the valvecover) while leaving the other side connected to the intake tract, as that creates an unmetered air leak. It's a mistake seen all too often (not necessarily on this forum though).

Assuming you were drawing clean air post-MAF through the crankcase, the PCV valve, and into the intake tract post-TB on your Mustang, then adjusting the flow rate of the PCV valve effectively adjusted the air bleed past the throttle body (the job of the IAC).

You only need an oil separator on the oil-laden side of the system (PCV valve to inlet plenum). If you're pulling any significant amount of oil through the fresh air side (from the intake tube to the valvecover), that isn't exactly great.

1FSTBRD
09-23-2015, 11:57 PM
Some more good advice. Since there's the two circuits on the adjustable PCV and that the idle circuit can be altered to have more or less flow at idle, wouldn't the IAC be nullified at cruise speeds? Would toning down the PCV make more vacuum resources available to the engine to pull more air in and minimize pumping losses?

racecougar
09-24-2015, 07:21 AM
No, the IAC increases duty cycle at part throttle to provide dashpot upon throttle close. There's a lot more to this.

Reducing the "air bleed" through the PCV to increase engine vacuum would increase pumping losses, not decrease them.

My advice: stick a stock PCV valve on there, install a quality separator, and drive on.

rzimmerl
09-24-2015, 10:05 AM
Bingo on Rod's last post, way over thinking a minor item in which no massive gains will magically appear. A good quality ~$150 separator is the easiest and best thing to install on an SC. I have literally no engine oil in any of my intercooler tubes etc. using an AMW PCV Separator. I also have a UPR system on my F150 Ecoboost that I would recommend their universal can too.

BirdofPrey97
09-24-2015, 12:15 PM
Bingo on Rod's last post, way over thinking a minor item in which no massive gains will magically appear. A good quality ~$150 separator is the easiest and best thing to install on an SC. I have literally no engine oil in any of my intercooler tubes etc. using an AMW PCV Separator. I also have a UPR system on my F150 Ecoboost that I would recommend their universal can too.

Shoot me your part number on the SC separator please.?.?

rzimmerl
09-24-2015, 01:16 PM
http://www.accmachtech.com/catchcans.asp

Looks like you are able to buy from them direct now. In the past I had to do group buys with a minimum 10 order, and did this 3 times. Look in the group purchase section for the details and installation pictures.

BirdofPrey97
09-24-2015, 01:54 PM
Thanks Ryan.

racecougar
09-24-2015, 01:58 PM
No oil whatsoever past the UPR separator on mine either. There are quite a few good brands on the market, as well as a flood of $10-$20 junk.

BirdofPrey97
09-24-2015, 03:20 PM
Dang. With tax and shipping its just over $188.

89SCfan
09-25-2015, 12:25 PM
Dang. With tax and shipping its just over $188.

Here is the one I use on my 2007 Hemi Jeep. Very good quality and not as expensive. It has prevented at least two quarts of oil from going through my intake system in the past two years.

http://www.custombilletstore.com/Hemi_Oil_Catch_Can_p/20010.htm

SuperCoupeDave
09-25-2015, 02:14 PM
I have a 13 F150 with the 3.5L EcoBoost, and there is a bad problem of valve coking. We use a catch can with check valves, and it almost completely keeps the oil and moisture out of the intake track. I empty my can every 2 weeks and theres times I get almost 12oz of crap out of it. Its pretty unreal.

1FSTBRD
09-26-2015, 05:05 PM
I've had extremely good luck with the Moroso air/ oil separator. I think that I may take out the A/C pump and mount a Moroso in there. JLT--though I haven't had any experience with it--looks like a really well made unit, as well.

1FSTBRD
10-04-2015, 02:28 PM
I'm still learning about an FI/ boosted system, and the idea/ suggestions of losing boost through a PCV that isn't totally sealed, seems to make sense. I'm going to put the adjustable PCV on the 'Bird today. For some reason, I think that any PCV is bound to leak a small bit under boost, just based on the way it rattles around freely. I'm going to mess around with the adjustment to see if it closes off.

My assumption is that a PCV would take a very short amount of time to close itself off under boost, and that between that and the vacuum solenoid for the boost bypass valve, that they are things that would close vacuum off so that air resources are not lost through the engine, correct? So if a PCV was also leaking boost (albeit a very small amount), one would think that the engine would go into boost, or would utilize boost a bit sooner?

racecougar
10-04-2015, 03:20 PM
As explained in post #13, the inlet plenum does not see boost.