Sam's build thread

[sambb]

crankcase to plenum part
the OE restrictor pill that sits in the tube just above the PCV
my setup sans the pill. PCV will handle vacuum pressures but not block boost anymore. The 1 way valve will do that more reliably.


Alright I need PCV system advice. To double double check the PCV system is not to blame for my excessive oil burn I looked into the PCV valve side of the system. I found that my PCV whilst switching wasn't sealing 100% when blowing into it/boost applied to it. Now Ive recently developed an oil weep at the base of the dipstick tube where it goes into the block and I thought that possibly the PCV was allowing boost pressurisation of the crankcase which could be causing oil to get past the oil control rings??
So new factory PCV has gone in and I decided to run a series OE check valve between it and the plenum to guarantee that no boost can get down to the crankcase. The PCV will regulate the crankcase flows but under boost the check valve will handle that more effectively. What I noticed when doing this though is that this tube contains a small air restricter pill in the PCV line. Its obviously there to regulate either peak flow out of the crankcase/cam cover when the plenum is under vacuum or could alter pressures too I suppose.
So PCV + 1 way check valve + restrictor is way too restrictive compared to stock. But PCV + check valve with the restrictor pill removed is slightly more free flowing under vacuum than the OE setup yet guarantees that boost pressurisation of the crankcase wont happen. I'm happy to run it that way to see if oil useage changes for the better.
So my question is, if I slightly free up the flow in the vacuum draw side of the PCV system by removing the pill, are there any adverse things that could result from that? I did the cam cover cap un screw and let it rattle away on its seat test and at idle vacuum I cant differentiate any difference in vacuum at the cam cover with or without the pill. Just wondering if the air restrictor pill for example might be there to prevent the PCV system taking a big gulp of oil when you close throttle under brakes and the oil surge sends a wave of oil up the front face of the crankcase. Surely it draws from above the windage plate though yeah? thoughts?????? Considering that the engine is modded with a hell of a lot more boost, blowby and not exactly driven like a prius the extra flow in the PCV system when under vacuum would be more in step with where it needs to be yeah?

[vwthunder]

What is the benefits of a TT hub upgrade, does it change the geometry much ?

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[Sydneykid]

What is the benefits of a TT hub upgrade, does it change the geometry much ?

Yep, the TT hubs are engineered for their standard lower ride height, so when used on another car that is lowered (from standard) they relocate the roll centre in a more desirable position. ie; the lower control arm ball joint is located lower on the hub.

Cheers
Gary

[Sydneykid]

PCV valving = black magic
The theory is simple, but the execution makes my brain ache.

The one way valving - It should do nothing under boost, closed off, shut, thou shalt not pass. It should only work under vacuum, so it can suck the nasty oily air out of the cam covers and crankcase. The OE one way valve has a limit as to how much boost they can resist, exceed that limit and they will leak. Of course car manufacturers don't publish how much boost their PCV valves can tolerate, so it's trial and error.

Flow limiter - But they shouldn't suck too much otherwise they will draw some oil with the fast (too fast) moving air. So there has to be a limit as to how fast they suck.

The leaking dip stick - Blow by will do that if the PCV valve is actually sealing, the pressure has to escape somewhere, either up past the rings or find a leak somewhere. Easy fix, pull the dip stick tube out and put some sealant around it.

My suggestion - stick a catch can in the PCV chain, that way you can measure how much oil is getting into the process. Or better still get rid of the PCV system completely, and just run a catch can. Oil in the combustion process is not a good thing, it costs power and causes detonation.


Cheers
Gary

[sambb]

I see that a lot, even on turbo cars. Just a 3 port catch can with a crank and cam cover feed. That might be fine for the track when the cam cover and crankcase will naturally vent into the intake, but what happens on the street where you're only sporadically under boost. Isn't the oil just going to go feral from crankcase vapour tainting it because it never gets evacuated when you're under vacuum? If that side of things isn't an issue then I'll happily piss the whole lot off.

[Sydneykid]

I see that a lot, even on turbo cars. Just a 3 port catch can with a crank and cam cover feed. That might be fine for the track when the cam cover and crankcase will naturally vent into the intake, but what happens on the street where you're only sporadically under boost. Isn't the oil just going to go feral from crankcase vapour tainting it because it never gets evacuated when you're under vacuum? If that side of things isn't an issue then I'll happily piss the whole lot off.

There's a few options, a lot of the Skyline & Evo guys run the PCV to the top of the catch can on the street, so any oil vapour gets sucked into the combustion process. Then disconnect/block off the PCV for the track, so it doesn't affect engine performance.

Cheers
Gary

[sambb]

I fitted a can to see what kind of blow by I'm getting. The stock setup is the crankcase line (somewhere between 5/8 and 3/4) joining with the cam cover (3/4) into a common 3/4 line going to the pressure regulation valve @ the TIP. I will run this system to the TIP when I can find a 90 degree bend of the appropriate size to run off the top of the catch can but for now its vent to atmo.
While I'm running 3/4 hoses off cam cover and crank now because that's what I had on hand, they'll be turned into 5/8 lines going to the can. Two 5/8 lines have a bigger cross sectional area than the common single 3/4 did anyway so that's not going to be a down size but will allow me to use the cans dash 10 AN fittings correctly.
I'm running presently without a PCV and its just the internal pressures that are sending blow by to the can. I'd seen tests done where at idle (PCV active) you attach a balloon over the oil filler of the cam cover. The balloon should neither fill or shrink ie no pressure build up. To test the pressures if running no PCV as I am now I did the same thing today with the balloon over the catch can outlet and found the same thing. No building pressure or vacuum generated in the catch can. That tells me that at least at idle there is no appreciable blow by past the rings or vacuum draw down past the stem seals? If the stem seals were shagged, at idle wouldn't you see a vacuum at idle inside the cam cover.? anyway it remains to be seen what turns up in the can. At the moment I'm seeing lots of condensation in the lines but its a longer term experiment.
If there turns out to be next to no blowby then my oil usage could be pinned more on either the oil control rings or the turbo I guess, s we'll see!

[Sydneykid]

If the inlet stem seals are shagged then you might see a small amount of vacuum. But if the exhaust stem seals are shagged then you might see a small amount of positive pressure. It's not a guaranteed test though. In a multi (lightweight) valve engine valve guide wear is not common, unless the oil quantity/quality is deficient. Stem, seals suffer from excessive heat, that's their weakness.

The larger diameter the hoses the lower the air speed through them, lower air speed means less oil vapour is carried. Being a turbo engine I run Dash 12 (20 mm) breathers on my Skyline, the Honda runs dash 10 (NA engine).

Condensation is completely normal, that's why oil temp needs exceed 100 degrees to "boil off" the water.

Cheers
Gary

[sambb]

Yeah I really see the importance of oil temp hitting 100 degrees asap now. The visual that the clear lines gives you is an eye opener re the amount of water carried in them that's for sure.
My can is a bit of a difficult one for sorting an exit to the intake. With the filter removed it's a 1/1/2in port. The oem PRV puck on the intake was only 20mm which I'm thinking isn't big enough for the throughput of 2 x dash 10 lines so I might block that port off and go to a 1 inch port somewhere on the intake instead. The PCV will have to stay in its oe position sucking directly out of the the block (indirectly from the head via the can). I'll get moving on that side of things soon to get it all legal.

[sambb]

YouTube

Goto 30 minute mark for Morris and Ingall giving a component by component run down of the non control parts on V8 Supercars. Pretty interesting stuff.