PCV valve,can I remove?
Team Owner
Joined: Jun 2000
Posts: 38,923
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From: Southbound
Cruise-In II Veteran
...PCV relies on a 1¢ spring, if this becomes weak or the valve slightly clogged up, your emissions device has just become a major intake leak...
Burning Brakes
Joined: Dec 2007
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Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
Just because a manufacturer fits something, doesn't mean it the best thing for your engine.
PCV was created to appease tree huggers, not excite car enthusiasts.
Burning Brakes
Joined: Dec 2007
Posts: 952
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Yeah designed along with all those other well known performance enhancers, the air pump, EGR, catalytic converters......
Just because a manufacturer fits something, doesn't mean it the best thing for your engine.
PCV was created to appease tree huggers, not excite car enthusiasts.
Just because a manufacturer fits something, doesn't mean it the best thing for your engine.
PCV was created to appease tree huggers, not excite car enthusiasts.
Also, any engine has blowby. No engine is 100% sealed. Blowby gasses do more harm in the oil than burned internally.
If you really believe pollution is hype, then you can drink some antifreeze. I'm sure the poison label is hype also.
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Yeah designed along with all those other well known performance enhancers, the air pump, EGR, catalytic converters......
Just because a manufacturer fits something, doesn't mean it the best thing for your engine.
PCV was created to appease tree huggers, not excite car enthusiasts.
Just because a manufacturer fits something, doesn't mean it the best thing for your engine.
PCV was created to appease tree huggers, not excite car enthusiasts.
but I have hooked up the PCV and then disconnected it when on the Dyno, and I saw no difference.
But I have also run with it and without it, and the blow-by all over your engine... that sucks!
I am not a tree hugger, my 3 boys and I all ride big 2 stroke dirt bikes... so this is not an issue for me.....
my vote: PVC
Show me a Dyno difference, I did not see any.
And for those that think it will dirty your heads.... I run Chevron and Shell (with some 100 gas) my last engine on breakdown at around 5K miles showed VERY clean heads and portals....
Thread Starter
Racer
Joined: Dec 2009
Posts: 308
Likes: 2
From: South Italy
At this time the car haven't the air pump, EGR, catalytic converters,and I think the ECM it's disconnected too.
In Italy we don't have restriction about pollution on historic car.
I'm going in confusion...
In Italy we don't have restriction about pollution on historic car.
I'm going in confusion...
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
A PCV valve isn't permanently open, it only opens during high manifold vacuum like idle, over-run and light throttle cruising. As soon as manifold pressure drops due to load it closes.
Removing it does not change the air-fuel mixture because that's regulated by the airflow through the carb. Remove the leak and you simply have more air flowing through the carb for a given throttle opening which it will match with fuel, hence part of the small performance gain.
I'd agree that no engine has zero blow-by, but they don't need to be 'sucked' out of the engine, a simple vent, however it's arranged is more than sufficient.
Ethylene Glycol, Polyethylene Glycol or Methanol?
Removing it does not change the air-fuel mixture because that's regulated by the airflow through the carb. Remove the leak and you simply have more air flowing through the carb for a given throttle opening which it will match with fuel, hence part of the small performance gain.
Ethylene Glycol, Polyethylene Glycol or Methanol?
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
Hey... This is always a big to do about nothing topic.
bottom line for you... probably wont make a darn bit of difference.
you have a low power stock 350... correct? so lets say you hook it up... you gain a cleaner engine and valve covers, and loose... what 1-2hp MAX?!?!?.... I showed no difference when on the Dyno for me....
I say put it on and dont smell the oil as it drips off your valve cover onto your exhaust manifold....
AAHH..... but some love the fresh smell of napalm in the morning... i mean oil...
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Thread Starter
Racer
Joined: Dec 2009
Posts: 308
Likes: 2
From: South Italy
Hey... This is always a big to do about nothing topic.
bottom line for you... probably wont make a darn bit of difference.
you have a low power stock 350... correct? so lets say you hook it up... you gain a cleaner engine and valve covers, and loose... what 1-2hp MAX?!?!?.... I showed no difference when on the Dyno for me....
I say put it on and dont smell the oil as it drips off your valve cover onto your exhaust manifold....
AAHH..... but some love the fresh smell of napalm in the morning... i mean oil...
bottom line for you... probably wont make a darn bit of difference.
you have a low power stock 350... correct? so lets say you hook it up... you gain a cleaner engine and valve covers, and loose... what 1-2hp MAX?!?!?.... I showed no difference when on the Dyno for me....
I say put it on and dont smell the oil as it drips off your valve cover onto your exhaust manifold....
AAHH..... but some love the fresh smell of napalm in the morning... i mean oil...
yes I have a low power stock 350,and I'm agree when you say you can feel the difference between 1/5 HP especially if you don't use in the track.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
A PCV valve isn't permanently open, it only opens during high manifold vacuum like idle, over-run and light throttle cruising. As soon as manifold pressure drops due to load it closes.
Removing it does not change the air-fuel mixture because that's regulated by the airflow through the carb. Remove the leak and you simply have more air flowing through the carb for a given throttle opening which it will match with fuel, hence part of the small performance gain.
I'd agree that no engine has zero blow-by, but they don't need to be 'sucked' out of the engine, a simple vent, however it's arranged is more than sufficient.
Ethylene Glycol, Polyethylene Glycol or Methanol?
Removing it does not change the air-fuel mixture because that's regulated by the airflow through the carb. Remove the leak and you simply have more air flowing through the carb for a given throttle opening which it will match with fuel, hence part of the small performance gain.
I'd agree that no engine has zero blow-by, but they don't need to be 'sucked' out of the engine, a simple vent, however it's arranged is more than sufficient.
Ethylene Glycol, Polyethylene Glycol or Methanol?
That is simply wrong, the ONLY TIME a pcv valve would be closed should be on engine backfire, otherwise it meters itself.
Whether you are using a pcv, an old road draft setup or an exhaust scavenger system, evacuation helps, if nothing more than to maintain the integrity of the seals and gaskets.
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
So you disagree with me that the PCV valve doesn't open and close, yet you say it meters itself, so if it's not metering it's opening and closing what exactly is it 'metering'?
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
As mentioned above it is a controlled air leak as the intake sees it and keeping its flow as consistant as possible allows the carb to do it's job more accurately.
If you are a more visual type of person, extend it into the cab with a longer hose and observe it's operation.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
You can run breathers to vent excess pressure and keep the rear main seal from leaking, but breathers can't ventilate the crank case to remove airborne contaminants.
Some of the blowby gasses are unburnt fuel that go past the rings on the compression stroke, so it's not all inert junk that is being re-cycled through the motor.
I don't run my vette often enough to lose any sleep over pollution, but I run a PCV valve to help keep the motor clean.
Racer
Joined: Dec 2008
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From: Topeka Kansas
St. Jude Donor '09-'10-'11-'12-'13-'14,’18
Le Mans Master
Joined: Nov 1999
Posts: 5,768
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From: San Diego CA
Keep the PCV, its benefits far outwheigh any detriment to your engine output. In any case the power loss is so insignificant as to be nigh on to indetectable. A couple of HP at the most and that is probably less than the margin of error on typical roller type chassis dyno.
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
Maybe I am just coming at this from a different angle to you guys.
My background is race cars and small European cars that produce a 1/3 or 1/2 the power of a Corvette.
In both those cases, getting back a few hoursepower is a real plus.
I do disagree with the argument that it's a 'must' for engine longevity. In Britain we didn't get widespread PCV until the late 70's - early 80's and engines lasted just fine before then.
My background is race cars and small European cars that produce a 1/3 or 1/2 the power of a Corvette.
In both those cases, getting back a few hoursepower is a real plus.
I do disagree with the argument that it's a 'must' for engine longevity. In Britain we didn't get widespread PCV until the late 70's - early 80's and engines lasted just fine before then.
Racer
Joined: Aug 2005
Posts: 308
Likes: 0
From: Salem MA
I'm pretty active in the RWD volvo community. I have a 940 turbo that runs a 13.4 quarter mile. many volvo guys also remove the PCV and vent to atm or use a catch can. I played around with a few PCV alternatives but in the end went back to stock because any other set up required babysitting and/or just didn't matter for performance. I have upgraded my turbo twice and both times compressor efficiency is my limiting factor for power not generic 'detonation from PCV' so considering my volvo makes about 240 WHP from 2.3 liters and the PCV is not a limiting factor, the PCV is also not a limiting factor for any semi-normal naturally aspirated american V8.
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
I haven't suggested that a PCV system limits power, simply that IMO it is an emissions device that is unnecessary and may have a small impact on performance.
I can understand many peoples attitude of 'I've got 400bhp, I wont miss 5bhp' but in my background of race cars and cars that maybe only make 120bhp, that 5bhp makes a difference.
I think maybe I forget that many Corvette owners are Sunday cruisers and as long as the thing lays rubber and runs smooth they don't care about eking out every last BHP.
I can understand many peoples attitude of 'I've got 400bhp, I wont miss 5bhp' but in my background of race cars and cars that maybe only make 120bhp, that 5bhp makes a difference.
I think maybe I forget that many Corvette owners are Sunday cruisers and as long as the thing lays rubber and runs smooth they don't care about eking out every last BHP.