Pcv valve on a turbo m20

[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.

[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?

[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?

[turbski]

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

[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]

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..

[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).

[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.

[turbski]

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?

[ak-]

Run a long line under the car/firewall - that got rid of the smell for me

[turbski]

+1 on the pictures. I would like to see some simple setups. im currently venting to atmosphere and hate the smell/ residue it leaves everywhere.

[arashjahn]

either run to the exhaust or turbo inlet.
catch can to exhaust

or just straight vc to turbo inlet.

Any picture out there of clean A-N lines from the breather on turbo’ed m20s going to the exhaust?
The smell of an open atmosphere catchcan is starting to get tiresome.

[kamotors]

either run to the exhaust or turbo inlet.
catch can to exhaust

or just straight vc to turbo inlet.

[Kozworth]

Sorry for some reason this wasn't clicking in my head. I'm used to just reading about moving pcv valves. I also kept thinking guys deleted the oil return tube/pcv tube on the drivers side that goes from the block to intake mani. I am probably taking the lazy route for the time being thanks

[travish325]

Smh