Pcv valve on a turbo m20

[ak-]

would running it into the turbo cause any problems for the health of the turbo. I have no problems running it under the car. it may very well be the way I go at this point, just curious what effect running it pre turbo would have on vac to the crankcase/ engine as a whole?

It'd have problems with your motor eventually in my experience.
Since it's oil vapor coming out of your crankcase, it will reduce the octane rating of your fuel and start to eventually ping worse and worse.

Some have done it successfully, but their engines must be incredibly stout or something.

If you could come up with a very good oil separating catch can in-line to the valve cover and pre-turbo elbow, try it. Just keep an eye on your AFR's and fueling.

[citizen_insane]

would running it into the turbo cause any problems for the health of the turbo. I have no problems running it under the car. it may very well be the way I go at this point, just curious what effect running it pre turbo would have on vac to the crankcase/ engine as a whole?

You can cause damage to the compressor wheel, but it would take a long time. The droplets of oil in the air will impact the blade and cause erosion.


In OEM applications with low pressure EGR they coat the compressor wheel to prevent this damage (from water droplets in that case).

[turbski]

I have another post under the alternative tuning section. The reason I asked is, would hooking it up pre turbo create better vac in the system? My thought was no..

[LowR3V'in]

hell yeah it would. it'll suck your finger in what u think happens to gas?
it's a good idea but then, nobody wants to deal with it building up in the intake.

[turbski]

it would create better vacuum for the crankcase portion of the motor, but how would this help with the intake vacuum readings?

[turbski]

unless the vac on the bottom of the pistons is helping to seal the rings better, or in a word, "cancel out" the effects of the blow-by?

[Fraser]

This is slightly related- I was wondering about what you guys do with the fuel tank breather valve that plugs into the nipple on the underside of the throttle body? Can that thing handle boost? Little hose clamp maybe to keep it on under pressure?

[Q5Quint]

Found this online from a caterpillar reference:

New engine- Blowby [ft3/min] = rated power [hp]/120
Worn engine- Blowby [ft3/min] = rated power [hp]/40

so at as stock 170hp you could have 1.41cfm new and 4.25cfm worn blowby.

At a turbocharged 300hp it could be 2.5-7.5cfm. This sounds like A LOT but a 300hp engine is about 208cfm so you are at only 4% blowby even if it is worn bad.

A little airbrush compressor for painting tshirts is usually around 1cfm, so just imagine having 7 tshirt airbrushers shooting oily vapor somewhere under your hood. You want it to go to the right place and not to an aesthetic oily sunset and palm tree that says 'terry and jerry' under your hood, right?

On my old turbo e30 I just capped the throttle body line and ran a new line from the valve cover into the lid of a Gatorade bottle. Then I ran a 2nd line from said bottle over to the intake in front of the turbo. Worked like a charm and kept the blowby from shooting the dipstick out and 7 airbrush t-shirters from spraying oil onto the hood and everything. Didnt notice oil in the intercooler or turbo since the top quality Gatorade bottle was catching it all.




I did have to rtv and ziptie some of the throttle body vac fittings on because they would blow out under boost. 12psi will push a lot of things apart on the pressure side. I dont remember if this was the fuel canister breather thing or not, but there were a lot of little hoses that needed vac and had what looked like valves on them that I did have to RTV and zip tie on because they were too small for metal clamps.

Look at how most turbo cars are from the factory with their pcv systems. My old benz is a tube that goes from the valve cover to to air filter box in front of the turbo. No catch can or anything. It is not as big a deal as most people make of it, but the oil does collect in the bottom of the air filter box and is wiped out when you change the filter. Neat 1983, you smart.

If your catch can setup is not stout enough you will pull oily vapor into the turbo and boost pipes and they will get all nasty, and maybe shoot oil onto the turbo itself. Don't do that, but do something.

[turbski]

is there any way to remove and seal around the tube that goes from the block to the bottom of the intake manifold without pulling the head ? I have a pretty decent leak right there that id like to take care of.

[Northern]

I haven't touched an M20 in a few years, but you definitely don't need to pull the head. You might be able to get the "bitch tube" out by pushing it down into the block against the spring without removing the intake manifold (I think there's just enough space). If not, you'll need to pull the manifold, which might be less of a pain in the ass anyway.

[turbski]

Ya it looks like less hassle to just pull the intake off, I tried a couple times but im gonna end up bending the tube if I don't pull the intake. unless im missing something?

[Q5Quint]

Zip tie the springs down and replace the o-rings at the top/bottom.

The tube just connects the valve cover to the crank case, so without proper vac being pulled on the valve cover your oily vapor will leak out of it and other seals.

[turbski]

managed to replace the upper o ring but unable to get at the lower... the one that's actually leaking..... meh, winter will be hear soon enough and ill do it while the car is up in the garage for snow season.

Would like to know more about your Gatorade bottle though,
I have a cheap vent to atmosphere catch can, with a cheap little filter on top of it to release the gasses, I get a little bit of "stuff" in the bottom of it but hardly worth taking note of the amount. even with the filter I get a noticeable amount of gasses escaping from said filter, stinks a fair amount...… would it be ok to just by pass filter and send it to the turbo or is the exhaust with an AN line preferred method?

[Q5Quint]

would it be ok to just by pass filter and send it to the turbo

Yes, it will stop the stinking and make your leaky o-ring less of an issue.

Your vent currently isnt sucking, so you wont see anything in the filter unless the crank and valve cover are pressurized which would send gas out your filter. The gatoraid bottle catch can to intake suction will get you a full gatoraid bottle every 2 months or so. That is water and oil that is just sitting inside your engine without that suction.

or is the exhaust with an AN line preferred method?

I would highly advise against this as it would likely kill your catalytic converter and/or you if the oily gas catches fire in your exhaust. Exhaust back pressure could actually push backwards into your 'vent' which would make things awkward, so I wouldnt do it at all even with some kind of check valve.

My old diesel benz dumps its valve cover vent into the filter box pre-turbo. If you dont have a nice round metal filter cover to catch turbine blade destroying droplets and oil your filter at the same time (its like a free k&N every time!), make sure to use a catch can or inline filter.

cut a hole in the cap, shove two hoses in, goup up cap with rtv. Screw on bottle and done. Or just buy the ebay/amazon one for $20

[turbski]

How much oily vapor does everyone see when vented to atmosphere? Mine at an idle will puff out a bit of vapor even with a catch can and filter dumping to atmosphere.