Breather to Exhaust - Venturi PCV System

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Keeps oil out if intake and creates Vacume in the crankcase? My 1fzfe has a major valve cover leak and causes it to use quite a bit more fuel. After venting crankcase to atmosphere my milage skyrocketed, but I developed leaks all over the place. I'm gonna weld one of these jobs on to replace the crank Vacume and keep the better milage. I say better cus even stellar 1fzfe milage still sucks. Yes I could redo the valve cover seal, but that is easier said than done.
 
gerg said:
Keeps oil out if intake and creates Vacume in the crankcase? My 1fzfe has a major valve cover leak and causes it to use quite a bit more fuel. After venting crankcase to atmosphere my milage skyrocketed, but I developed leaks all over the place. I'm gonna weld one of these jobs on to replace the crank Vacume and keep the better milage. I say better cus even stellar 1fzfe milage still sucks. Yes I could redo the valve cover seal, but that is easier said than done.
Click to expand...

But a catch can (with drain to sump) and breather routed to the intake also does the oil seperation and vacuum. I can't help thinking an exhaust system is just going to suck oil out your engine and blow it all over anything you tow. Not to mention embarassing blue smoke.

I'm now down to ~15 litres/100km after I remapped my petrol guzzler. Down from a worst of 30+. How's yours doing?
 
I'm still fitting a catch can but the polluted vapour that comes out of it will burn off in my exhaust rather than pumping that corrosive, oily crap through my nice new engine and turbo
 
What's your exhaust temp that far back?
At cruise I have ~380-420C preturbo. It is likely cool enough to not even burn oil a few feet further down the exhaust.
 
Here's the catch can in situ
IMG_0833.webp

I stuffed it with a full packet of coarse stainless steel wool
IMG_0831.webp

so it looks like this through the outlet ports
IMG_0832.webp

this is supposed to give the vapour plenty of contact surface area so it leaves the oil behind and the venturi just draws off vapour
IMG_0750.webp

Good question Dougal, I'm still in trial and error mode at this stage, my EGT (pre turbo) cruising today at 100km/hr was only 300'c so I have plenty of room to add more fuel to get the temp up :) It may well be too cool where I've paced it.

I'm changing oil tomorrow to a 20w x 60w mineral, away from the semi synth that's in there ATM. I put that in there 1 week pre project and didn't really drive it but I had very little blowby prior so maybe going back to the older style, thicker oil will help with the blowby.

If it doesn't, I'll have to (blank off the first) put in a second venturi port in between the O2 port and the muffler which is a bit of a tricky one. Because of the location, but also because I'm a bit worried about it affecting my AFR reading from the probe.
IMG_0429.webp


It didn't hardly blow at all pre project, so my last reason (that I can think of) for why it is blowing so much is that the oil feed pressure to the turbo is too high and it's pushing into the compressor.

Does anyone know if that's possible?
 
My valve seals seem to leak a bit which gets really bad with no crank Vacume as well as a huge valve cover leak. My engine basically doesn't burn any appreciable oil routed to the intake, so shouldn't routed to the Venturi in the exhaust. As soon as I blocked off the crankcase vents to the intake milage went from 20l/100k to 15.3/100k which is 15us mpg but that's still terrible. I dont think they actually do much better than that unless you get into them and do a head job or a rebuild or something.
 
I'm not sure about my milage yet, I used to get about 13.5L/100km but I have now completely changed the motor and gone from a manual to an automatic transmission, stock to something quite different :-)

I'm still on my first full tank and my initial feeling is that it's gone up to about 16L/100km. I'm pretty ok with that because the auto pulls a lot of energy out of the mix, that's the reason for all the other mods as an offset. I have not been driving it particularly economically either.
 
Weld up concentric tubes, take the outlet from the top centre and make the inlet come in on an angle to start the cyclone.
 
Anyone got a link on these cyclones?

I'm really happy with this setup, but I may move the venturi pickup to just past my turbo, into the highest pressure/temp zone, this system is amazing but when you are at idle there is definitely not enough heat down that end of the exhaust to burn off the vapour so I get a smelly, slightly smokey exhaust swirling around the car at the traffic lights.
 
The idea was to remove the oily/corrosive input to my turbo intake and then intercooler.

Update, the system works really well. So well that it pulled a litre of oil out of the motor and out the exhaust all over the back of the car after only 1 tank of fuel and I've had to put the catch can outlet back to the suction side of the turbo :-(

Another costly lesson, at least the info is out there (on IH8MUD) now, still worth having a crack at something new.
 
Can you do anything inside the rocker cover to keep the oil inside the engine there? Internal seperation is better than external.
 
I'm beginning to believe that the oil pressure reducer between the block and the head may have somehow not been fitted when I fitted the head. One of the guys from Engines Australia tells me that if it's left out (I don't remember ever seeing it - oblivious) you can get high pressure oil flooding into the top of the head, then on into your cylinders via the valve stem seals. Additionally, I've learned that the valve stem seals fitted to the brand new heads are crap. This plays out with the smoke I'm getting since I fitted the head, particularly if it's sat still for few days.

So I'm preparing to pull the head off again, new genuine #5 gasket, new genuine valve stem seals, new orifice plug, new head bolts, might as well chuck a set of new rings through it to be sure, I won't be pulling it apart again :-)

For all that, it goes bloody well. I had it on North Stradbroke Island last week, after an hour of pushing heavy sand at high tide on a 27'C day it still only hit 500'C pre turbo EGT so I'm pretty happy.

I'm going to drop the timing back to 1.60 from 1.90 as it's quite rattly which doesn't feel right. It will be interesting to see how it effect performance. It was originally set to 1.45

What is everyone else running their timing at?
 
Not one swear word in your post, you must have exceptionally good self control :) no doubt you will look inside the intercooler on disassembly to discount oil coming through from the turbo.
 
Hahaha, yeah, I have been swearing quite a lot since about January this year. Funny, that's when I started my one month project ;-)

I can verify that the I/C was oil free when it (breather) was running out the exhaust, in fact I was so sure (initially) that my problem was being caused by excess turbo oil feed pressure pushing oil into the turbo, I trialled a reducer in the oil feed to the turbo.

The oil gauge then showed an increase of 15psi at idle and I then blew more smoke. Changed it back, oil smoke reduced. Seems to play out with the reducer to the head being missing. The valve stem seal change out is just precautionary to make sure I don't have to take the head off again.
 
I might as well fit the 80L/min water pump to the I/C circuit while it's in bits, even though the bosch cobra is now all sweet, I can use that for a bush shower for wifey when I build my big underfloor water tank
 
thanks for posting your finds to help others from making the same mistakes. alot of forums have people telling other people what will and wont work when they've never tried it themselves..

:cheers:
 
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