PCV valve for boosted engines (Page 2/4)
ericjon262 JUL 20, 07:26 PM
it would be interesting to see which method generates the greatest pressure drop.
pmbrunelle APR 25, 10:55 PM
In a misjudgement I made (penny wise pound foolish), I ordered an aftermarket PCV valve for a 1995 Toyota Supra 3.0 Turbo from Rockauto. The brand was Intermotor.

I saw this thread, thought I might get lucky with an aftermarket part, but no. Real POS, I could blow through it the wrong way just as much as the stock (or stock replacement) Fiero PCV valve.

Then, I decided to head to my local Toyota dealer. I tell the parts guy that I have a "1995 Toyota Supra 3.0 Turbo", he asks if I have the 2JZ engine, then I reply "I suppose so", and then he looked at me funny.

$19.62 CAD (taxes included) and a week later, I have the Toyota 12204-46020 PCV valve in my hands (plus a spare one, for an additional $19.62). I blew into the PCV valve to simulate boost, and it didn't leak.

The purpose of this message is to corroborate fierosound's findings.

I have yet to test the fitment of the PCV valve with the grommet and elbow.

[This message has been edited by pmbrunelle (edited 04-26-2018).]

pmbrunelle APR 25, 11:01 PM
Nobody has discussed this, but for crankcase ventilation in "problematic cases", why not consider a road draft tube?

Sometimes, simple solutions are right under our noses, if we care to turn the history books back a few pages.
wftb APR 26, 09:42 AM
On my turbo 2.2 ecotec , there is no PCV valve, just a hose fitting on the valve cover. There are internal baffles that prevent the oil from getting in to the hose that I have routed to the fresh air side of the intake. I think all the 4 cyl ecotecs are the same. I don't have a catch can and do not see oil in the hose. I think the tighter tolerances of newer engines prevents pressure buildup in the crankcase.
fierosound APR 27, 10:25 AM

quote
Originally posted by wftb:

On my turbo 2.2 ecotec , there is no PCV valve, just a hose fitting on the valve cover. There are internal baffles that prevent the oil from getting in to the hose that I have routed to the fresh air side of the intake. I think all the 4 cyl ecotecs are the same. I don't have a catch can and do not see oil in the hose. I think the tighter tolerances of newer engines prevents pressure buildup in the crankcase.



Possibly true. But we're not talking about piston blow-by.

We want a PCV to be closed when the manifold is under pressure when being boosted by either a turbo or s/c.
Otherwise you will lose some boost as that pressurized air will will blow through the PCV into and pressurize the engine's crankcase.

If you installed a turbo on your Ecotech you likely need to do something similar.
wftb APR 27, 01:29 PM
The PCV line goes to the non pressurized side of the intake. So no buildup of pressure in the crank case is possible. I have been turbo for 10 years now and have not had any problems. Some people just put a small air filter on the vent fitting but I like the fumes to be drawn in to the engine.

[This message has been edited by wftb (edited 04-27-2018).]

fierosound MAY 01, 02:05 AM

quote
Originally posted by wftb:

The PCV line goes to the non pressurized side of the intake. So no buildup of pressure in the crank case is possible. I have been turbo for 10 years now and have not had any problems. Some people just put a small air filter on the vent fitting but I like the fumes to be drawn in to the engine.



The only non-pressurized location would be upstream of the turbo.

On the stock V6 the valve cover toward the passenger cabin has a tube to the rubber tube connecting to the TB for fresh filtered air.
The valve cover on the trunk side has the PCV that routes to the intake manifold so engine vacuum can pull the PCV open and draw the fumes into the engine.

Item 10 is fresh air to engine tube.







Of course, when my s/c is producing boost and the intake is pressurized,
the PCV needs to act as a check valve which is why I needed a good one.
My "fresh air" connection is after my air filter but ahead of my s/c.

[This message has been edited by fierosound (edited 05-01-2018).]

wftb MAY 01, 09:46 AM
So you either re route your PCV lines so they both go in to your intake after the air filter but before your supercharger or find a PCV valve that will close well enough to prevent the pressure buildup. From my experience with PCV valves over the years most of them are cheap pieces.So maybe you will find a good one maybe not. The PCV valve will still function if it draws air from a source other than your intake manifold. The air in the intake before your supercharger is under vac anytime the engine is running. The other thing you could do is incorporate a brake booster check valve after your stock PCV valve. The booster check valve holds up very well against boost.
pmbrunelle MAY 01, 09:14 PM

quote
Originally posted by wftb:find a PCV valve that will close well enough to prevent the pressure buildup. From my experience with PCV valves over the years most of them are cheap pieces.So maybe you will find a good one maybe not.



Uhhhh, the subject of this thread is a PCV valve that closes under boost...

...a PCV valve that Toyota felt good enough about putting on a production turbo car.


quote
Originally posted by wftb:
The PCV valve will still function if it draws air from a source other than your intake manifold. The air in the intake before your supercharger is under vac anytime the engine is running.



Anywhere that's upstream of the throttle body won't be under vacuum. So it won't positively ventilate the crankcase. But fumes should be able to passively wisp into the intake tract and still be consumed... just not positively.

fierosound's throttle is downstream of his supercharger, so the air coming into his supercharger will never be under vacuum. But a PCV hookup between the throttle and supercharger as in a typical roots blower type arrangement should work well, I think, and avoid boost.

On my car, since I will be using water/meth injection, oil contamination is a big risk. Good crankcase ventilation will be important for my Fiero.

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On topic, the Dorman 42332 valve cover grommet works OK. It's not perfect, but it's rather acceptable. I'll roll with it.

The Fiero PCV elbow does not fit onto the Supra valve in a manner that conforms to my standards.

I am researching solutions for this now, when I have part numbers, I will post them.

[This message has been edited by pmbrunelle (edited 05-01-2018).]

wftb MAY 02, 12:39 PM
The air in between the air filter and the throttle valve might not technically be under vacuum but the air is constantly being drawn in one direction towards the throttle body whenever the engine is running. So if you vent your PCV valve there it will be more than a passive vent. My point is that you can do this with your stock PCV valve and have adequate crankcase ventilation and not have to buy a different PCV valve.

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86 GT built 2.2 ecotec turbo
rear SLA suspension
QA1 coilovers on tube arms