Re: Adjustable PCV - dual flow
With 8 valve Turbos, I allow the crank case pressure to exit unrestricted through a large hose.
If you block the crank case vent line, the engine will most certainly leak past seals etc.!!
Pressure builds in the crank case naturally, blow by is the main contributor, it can not be contained, and trying to contain it can result in leaking seals !! This pressure doesn't need to be taken, its going !!
This pressure vapor contains moisture, and assorted by products of combustion, all octane reducing, and its going somewhere!!
Where it goes is up to you. Straight out to the atmosphere, or air box, or PCV, engine air intake etc., your choice.
Any restriction to natural flow can create a venturi effect that can even suck liquid oil. Any oil that collects in the intercooler, etc, is oil that was snatched from the crankcase breather and rerouted to the engine air intake, as in vacuum.
Thanks
Randy
Re: Adjustable PCV - dual flow
older cars used to have a filtered (or not) vent and what they called a "road pipe"
the vent would often be on the oil fill tube or stack - thinkold small block chevy for a mental image
the road pipe would extend down below the car where the air passing under the car would draw the fumes outta the crank case
on my early hemi it started at the back end of the lifter valley pan under the intake and extended over to one side and down at the back corner of the motor
I'll add , the valley pan was a two piece deal , an upper and lower piece , stamped so that there was an inch or so gap between the halves when placed on the motor - this prevented lifter splash from going down the road pipe I presume
the late model tbi valve cover with the silencer shield under it would have a simular effect I presume
Re: Adjustable PCV - dual flow
Quote:
Originally Posted by
GLHS60
The pressure takes its self out of the engine. That's what pressure does, provides movement.
You NEED no restriction to the pressures flow.
Thanks
Randy
Simple physics dictates that positive pressure will flow to a point of negative pressure easier than neutral (atmospheric) pressure.
Re: Adjustable PCV - dual flow
Quote:
Originally Posted by
Johnny
Right, but that "flow" might be out the seals if not dealt with....right?
I don't think people want to admit that most of their driving is not racing. Yes, a PCV could allow better ring seal performance, emissions, etc at low rpms and low loads. Yes its not ideal at WOT. Thats why most setups have breathers. Maybe 2.2/2.5's didn't pass some emissions test and this was a workaround.
I wouldn't lose sleep over octane reducing crankcase gasses. Its the modifications we do for performance that really compromise these systems. My exhaust evac works great at WOT but ruins the PCV function as the exhaust valves leak more air due to exhaust pulses than the PCV can deal with (already needs to be suckign up blowbye at idle etc). I did pick up a higher cracking pressure GM exhaust check valve and never installed it.
I have an added check valve (other platforms add these) on my PCV but I never tested to see if my PCV leaks under boost.
Some of us might have a modified car but we also might have a stock vehicle we like that way.
Re: Adjustable PCV - dual flow
Quote:
Originally Posted by
supercrackerbox
Simple physics dictates that positive pressure will flow to a point of negative pressure easier than neutral (atmospheric) pressure.
If you want your engine to inhale crank case vapors you can. My reply to Johnny was letting him know crank case pressure can find its own way out. Crank case pressure doesn't "need" to be drawn out, popped dipsticks etc. have proven this.
Thanks
Randy
Re: Adjustable PCV - dual flow
Quote:
Originally Posted by
puppet
Are we talking about the same thing? ... I don't think so. I don't advocate a PCV setup.
As we're on the same page as to ditching the PCV, all is good with me!!
I was addressing the oddity of our engines crank case not having a fresh air intake, probably came out wrong.
Thanks
Randy
Re: Adjustable PCV - dual flow
they do have a breather .. that stupid hose running from below the pcv valve to the air cleaner box IS the crankcase breather
it's the same enclosed crank case breather set up as found on any V8 smog motor with the hose running from the valve cover to the air cleaner above the carb , where on the inside of the air cleaner where the hose goes you find a little filter
whole reason it's in the air cleaner is so that it dosen't off gas directly to atmosphere - smog laws
the little filter is supposed to keep crank case crud outta the carb
problem with ours is the oil vapour in the hose condenses when it cools and runs down hill to the air cleaner , instead of running back down to the valve cover where you would never notice it
now if it helps , picture that V8 smog motor crank case vent hose running from the valve cover to the air cleaner , put a T in the middle of it and stick your PCV in the T
turn it upside down and you have what's in our cars ... and the reason it dripples oil all the time
well , bad design ... and gravity
- so two reasons ..
Re: Adjustable PCV - dual flow
The difference is easy to understand on the V8 system you describe. The PCV is drawing crankcase vapors out of one valve cover and fresh air enters the crankcase from the other.
The generic V8 illustration featuring the magic adjustable PCV shows this exactly.
8V Turbo engines only have the exit nipple, the T you describe is not capable of allowing fresh air into the crank case while the engine is running, as crank case pressure is already going out.
TBI engines are capable of allowing fresh air into the crank case as they have two valve cover nipples, one drawing from the crank case through the PCV and the other allowing fresh air in.
Thanks
Randy
Re: Adjustable PCV - dual flow
So would an option be to tap a second hole in the valve cover with a breather Filter. I would think it would just be another vent under Boost.
Re: Adjustable PCV - dual flow
You can find a later TBI valve cover that would have an extra vent tube. They were cast aluminum for I think '93-'94 models. But obviously it wouldn't say TURBO on the cover.
Re: Adjustable PCV - dual flow
Quote:
You can find a later TBI valve cover that would have an extra vent tube. They were cast aluminum for I think '93-'94 models. But obviously it wouldn't say TURBO on the cover.
this what I use.
Re: Adjustable PCV - dual flow
Hey Guys, sorry to bring up an old thread, but why couldnt you use something like this on a turbo valve cover?
https://scoutparts.com/Oil_Breather_...yABEgIZLvD_BwE
I want to put a catch can on the shadow, as the vent tube is making a mess down low. I was going to make a closed loop system, using the stock three way "T" off the valve cover, using a supra PCV to the intake. The lower exit to a sealed baffled catch can without a vent, then to the intake pipe with a venturi barb in it to draw vac. I was going to use a TBI cover to add a vent on the second barb, but found this, was going to see if it would fit. Your thoughts?
Re: Adjustable PCV - dual flow
some have used an oil cap like that
hood clearance might be an issue for some
I guess we're all a little to cheep around here but the real solution is a crankcase vacuum pump like the morosso one or such
literally pump the vapor outta the crankcase and get fantastic ring sealing to boot
and no fresh air blowing past the rings (no lost power)
and a lot easier to fit to the car than a dry sump
://www.jegs.com/i/Moroso/710/22644/10002/-1