Crankcase breather question

I want to know what peoples opinions are about running my breather system. What I am thinking is that the way my system is currently set up it is not really doing much, if anything, apart from looking like cack.

If you take a look at the picture I have supplied you will see what I am proposing. I want to take the small filter (circled in yellow) and place it on the exhaust side cam exit (circled in red). As you can see my system is a little different from normal as the intake side cam exit (circled in green is fed into my greddy intake manifold). So the normal breather set-ups do not really cater to me as they normally utilise both the exhaust side and intake side of the cam breather exits. The only other thing I could think of instead of just running the cam breather filter, would be to run a hose from the exhaust side cam into the intake pipe (circled in pink). I guess the question at this point would be do I really even need to do the latter or can I get away with just running the filter.

I have seen plenty of high powered Supras (Stateside) running aftermarket intake manifolds who run just a filter on the Ex side cam breather so I do not see why it could be a no-no.

Any thoughts ?

I to have seen lots of cars run with a filter in the exhaust side...

Only thing i would say is is you lose a piston then you have a chance of the oil being dumped on the turbo and a fire starting.

Im doing mine the same as the Envy car;)

I would do that Jamie but the greddy intake takes a feed from the intake side cam breather exit so all I would have is the exhaust side cam breather exit to play with. Meaning only one hose, hardly a circulatory system, more window dressing then functional.

I thought the only reason the cold side vent went into the plenum was for emissions? can that not be blanked of on the plenum?

I thought the only reason the cold side vent went into the plenum was for emissions? can that not be blanked of on the plenum?

I have no idea mate, I assumed the plenum needed that feed. I am just thinking out loud here but wouldn't that feed into the intake plenum assist in extracting or equalising the pressure within the crankcase ?

Blind leading the blind i think mate:D all the veilside plenums ive seen have no feed from the cam cover... i dont see why the greddy plenum should be any different.

Ok fair enough then. I will PM gaz and see what the cost of the breather system they offer is. That PHR system looks very nice and the dollar is quite low at the moment so hopefully the Envy solution is around the same cost.

http://www.mkivsupra.net/vbb/showthread.php?t=90746

With pics here

http://www.supraforums.com/forum/showthread.php?t=401969&highlight=breather

As Jamie says, you need a proper separator system not just a cheap catch tank. Oil back into the combustion chambers will only result one way - Meltdown.

Joe,

The RHS valve should be fed back into the intake plenum and the LHS should go directly into the intake pre turbo. Pretty much any other system is a compromise...except adding small individual catch cans to each breather side.

What problems would getting rid of the RHS valve cause then?

Joe,

 

The RHS valve should be fed back into the intake plenum and the LHS should go directly into the intake pre turbo.

It seems as if that is the most logical solution and the cheapest too.

Nothing. If you change the Cross Rocker cover breather pipe sizes to -12+ then you only need one Vaccume feed.

It seems as if that is the most logical solution and the cheapest too.

Not if you putting oil vapour into the cambers it wont be.

Not if you putting oil vapour into the cambers it wont be.

Oil Vapour won't matter, if it did the stock setup wouldn't do it!

Oil Vapour won't matter, if it did the stock setup wouldn't do it!

At 0.7Bar it doesnt, but at the level of tune these guys are I would have to say it is critical.

The Supra used to munch its way through Front Main Seals. Fitted an Envy modified Oil pump and the Breather system and have been running the car all this year without one FMS failure, Job done!

Thanks

Kevin

Crankcases are meant to run at a slight depression - about 20mBar below atmospheric. Partly for emissions purposes but also to increase the longevity of the main seals (cam and crank) and also to help drain oil from the turbo(s). Breather systems are split into two circuits: Primary, or part throttle, and secondary or WOT. As the names suggest they both operate differently depending on how the engine is loaded.

In summary if you run your WOT breather to atmosphere, then the lowest your crank case pressure will ever be is atmospheric. Actually, slightly above atmospheric as you have the pressure drop along the breather pipes acting to hold the pressure up a little bit.

If you bin the connection to the plenum from the intake side camcover (the primary breather) then you won't have a vacuum source at part throttle and so will again be running your cankcase at atmosperic pressure or above.

As for oil vapour charge dilution, a well designed breather system shouls carry over about 0.5 to 1g of oil per hour. I would suggest that if you are carrying over enough oil to dillute your intake charge then you should be trying to fix the route cause and get some rings that seal (or a less worn engine) rather than trying to cure the symptoms by putting a catch tank or separator on.

Incidentally, if you run a connection to the plenum, you must retain the PCV valve.

Thank you Digsy.

I assume the PVC valve is the black plastic tube on the cold side cam cover ?

So it is your opinion that I should just run a line from the hot side cam cover to my intake pre-turbo ?

Thank you Digsy.

 

I assume the PVC valve is the black plastic tube on the cold side cam cover ?

 

So it is your opinion that I should just run a line from the hot side cam cover to my intake pre-turbo ?

Yes and yes

-Ian

Cheers.

Another thread over on Supraforums confirms what you suggest.

http://www.supraforums.com/forum/showthread.php?t=402513

Post 15 especially.

For those who do not have access to the forums..

Unless you like sludge in your engine, you need to allow for POSITIVE CRANKCASE VENTILATION (PCV). Without it, the moisture (from condensation) that is naturally generated inside an engine will combine with the oil and form sludge over time. This is ESPECIALLY an issue in cars such as a lot of our highly modded Supras that are not driven very much. Installing a filter (such as K&N) on the passenger side cam cover and retaining the normal PCV valve between the driver side cam cover and the intake plenum will provide crankcase ventilation as intended by Toyota, and in my experience of about 6 years on this setup works perfectly. The same can be acheived by routing the passenger side cam cover vent hose to the turbo inlet pipe.

 

However, I don't like the idea of routing the blow-by back into the turbo inlet pipe (as happens when you route the passenger cam cover vent to the turbo inlet pipe) because the blow-by gases that are generated under boost conditions force the oil vapors that are normally in the crankcase, to go into the intake air stream (turbo inlet pipe). These vapors will condense on the cool walls of the intercooler, and therefore coat the walls of the intercooler and significantly decreasing its cooling efficiency over time.

 

One other thing to straighten out some misconceptions..... Under conditions of intake manifold vacuum (times other than moderate or hard acceleration) the flow through the crankcase will be that the air comes IN through the passenger side cam cover, circulates through the engine (as it NEEDS to do in order to evacuate the water vapors), then out through the intake plenum via the PCV valve/line. It is NOT normally sucked into the turbo air inlet (assuming you have the passenger cam cover vented to the turbo air inlet) because the vacuum in the plenum is many, many times greater than that in the turbo inlet pipe. They reason that Toyota originally vented the passenger side cam cover to the turbo inlet pipe is so that the air that was being sucked through the engine and eventually into the intake plenum would be FILTERED by the air filter and METERED by the MAF.

 

FWIW, I know a guy who has had the "both cam covers vented to a catch can" setup for about 3 years and he has a lot of sludge developing in his engine now. This is exactly what one should expect if he eleminated the PCV setup and just vented both cam covers. You NEED the PCV system.

 

ONE FINAL THING: The "routing to downpipe" thing WILL evacuate the crankcase VERY effectively if it is done correctly. This system works via the VENTURI effect, creating a very significant vacuum as the high-speed exhaust gases flow past the specially positioned tube. This has been used for many years on heavy equipment to suck the dust and debris from the intake air pre-cleaner that these machines run. The "pressure" in the DP has nothing much to do with it -- it's all about flow velocity to create the venturi effect and hence the vacuum to evacate the crankcase.

Some good reading in that link.. ita hard to know what to do for the best. this looks intresting setup. Along the lines of what b'have is doing with his breather.

Crankcases are meant to run at a slight depression - about 20mBar below atmospheric.

precisely

In summary if you run your WOT breather to atmosphere, then the lowest your crank case pressure will ever be is atmospheric.

I.e, atmospheric or above.

No vacuum.

geddit?

If you bin the connection to the plenum from the intake side camcover (the primary breather) then you won't have a vacuum source at part throttle and so will again be running your cankcase at atmosperic pressure or above.

...which is not a good thing

.. if you run a connection to the plenum, you must retain the PCV valve.

and test that it works as well. Some are clogged with oil and duff.

Why do we have to repeat the same things over and over?

Can't we make this a technical sticky and redirect future traffic to it?

Jamie, I believe Digsy has commented on that setup before and didn't rate it for road use, I think...

That looks extremely drag orientated, love the accessory belt

-Ian