PCV valve,can I remove?
Le Mans Master
Joined: Nov 1999
Posts: 5,768
Likes: 3
From: San Diego CA
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.
We on the other hand live in the real world where, even if we visit the drag strip or the road course on occasion a fraction of a HP is indetectable to us. None of this is to say that there arent some here on the boards who are interested in eeking out every last drop of power, this forum is nothing if not a broad group of people with differing goals.
In the case of the OP, I dont get the impression he's got a race car or that he's planning anytime soon to be in a position where 1-2 hp will make a difference, There are an awful lot of things racers do that we dont, and just because a thing is good for racers doesnt make a thing good for a street driven vehicle.
A far more challenging test for many of us may be to make as much power as is possible and remain emissions legal.
Last edited by fauxrs; Dec 15, 2009 at 09:49 AM.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
A couple of years ago, a guy on another forum, and I played around with using a FORD airpump, totally rerouted as to suck from the intake/pvc position, and actually put the crankcase under a vacuum of about 5-7 psi when idling/running down the road....the thing would suck some oil pretty bad, and so I needed a oil/air-fume separator can, and drain back into the oil pan/sump....I never went that far with it...too much PIA to drop the pan and mod the thing.....
at any rate, the trick was that running the sump at a actual vacuum using the belt driven pump was supposed to reduce crank drag and net up about another 5 hp or so....NO dyno runs by me on that claim, but maybe someone has done something there, do a search....
another thing that killed the idea for ME, was the problem with the fumes, they flat out stunk like cat's ***....lord love a DUCK they were BAD.....
at any rate, the trick was that running the sump at a actual vacuum using the belt driven pump was supposed to reduce crank drag and net up about another 5 hp or so....NO dyno runs by me on that claim, but maybe someone has done something there, do a search....
another thing that killed the idea for ME, was the problem with the fumes, they flat out stunk like cat's ***....lord love a DUCK they were BAD.....
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Jeez,..how can something so simple (PCV System) be so misunderstood.
You absolutely need it (or another crankcase evac system) to remove the harmful blowby gases, which include unspent fuel and water vapor, that conspire to cause sludge and corrosion in the crankcase.
ALL engines have some blowby!
A pair of breathers won't cut it. You need flow through the crankcase, created by vacuum. Fresh air replaces the harmful blowby gases. This also provides a bit of vacuum in the crankcase which a good thing; helps prevent oil leaks and any racer knows, that vacuum in the crankcase is good for horsepower. Few (if any) serious engines run without vacuum pumps at the drags.
For the street, there's no reason not to run a PCV system, unless you don't understand it's functionality.
You absolutely need it (or another crankcase evac system) to remove the harmful blowby gases, which include unspent fuel and water vapor, that conspire to cause sludge and corrosion in the crankcase.
ALL engines have some blowby!
A pair of breathers won't cut it. You need flow through the crankcase, created by vacuum. Fresh air replaces the harmful blowby gases. This also provides a bit of vacuum in the crankcase which a good thing; helps prevent oil leaks and any racer knows, that vacuum in the crankcase is good for horsepower. Few (if any) serious engines run without vacuum pumps at the drags.
For the street, there's no reason not to run a PCV system, unless you don't understand it's functionality.
Thread Starter
Racer
Joined: Dec 2009
Posts: 308
Likes: 2
From: South Italy
Race Director
Joined: May 2003
Posts: 10,956
Likes: 409
From: California
the fix
ok... we have 2 parties, one for no PCV because of yuckie going down the intake//......the other group to PVC, to keep yuckie out of the engine bay...
Both good arguments.... So here is what I am going to do.... best of both worlds.... Oil Catch Can..
http://www.pbase.com/rsrock/oil_catch_can
~$50
Both good arguments.... So here is what I am going to do.... best of both worlds.... Oil Catch Can..
http://www.pbase.com/rsrock/oil_catch_can
~$50
Burning Brakes
Joined: Dec 2007
Posts: 952
Likes: 0
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Jan 2003
Posts: 6,575
Likes: 1
From: Tuttle OK
Cruise-In VIII Veteran
3 pages on PVC kills me...
I have one, and a carb - lets talk about how jacked up my paint is here...
I have one, and a carb - lets talk about how jacked up my paint is here...
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
3 pages on PVC kills me...
I have one, and a carb - lets talk about how jacked up my paint is here...
I have one, and a carb - lets talk about how jacked up my paint is here...
Le Mans Master
Joined: Jan 2006
Posts: 6,505
Likes: 139
From: Butler Pa
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
Le Mans Master
Joined: Jan 2006
Posts: 6,505
Likes: 139
From: Butler Pa
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
Sorry I was a bit vague.
Some people have said that the reason why PCV is so important is because it's not good for the crankcase to have all those harmful gases going around inside the engine.
You've just said that on a good engine the amount of oil fumes and blow-by should be so small as to not effect performance.
I agree with you about the small amount, but then does it not also figure that you will not end up with an engine bay full of exhaust gas and oil if you have an open vent?
Le Mans Master
Joined: Jan 2006
Posts: 6,505
Likes: 139
From: Butler Pa
Racing engines have the oil changed quite often, so this isn't a big deal.
BTW, I hear people all the time reffering to a PCV as a "pollution control valve". It's a "positive crankcase ventilation" valve.
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
Many European engines, designed way after the late 60's/early 70's don't use PCV, they just use closed crankcase ventilation.
In these systems the crankcase vent is fed to the air filter housing/air box but the crankcase has no fresh air intake at all. These engines have done 100's of 1000's of miles with no detrimental effects to lifespan or performance.
PCV is a piece of emissions equipment, designed to reduce smog in engines built and tuned in the late 60's.
Today with cleaner fuels, better engineering, better oils and better tuning it presents such a small amount of pollution it's really not that big a deal.
Although it may be small, having spent ages building and tuning an engine I want maximum available performance out of it. If that means not feeding a small amount of garbage back in to the intake then I'll do it.
Le Mans Master
Joined: Jan 2006
Posts: 6,505
Likes: 139
From: Butler Pa
Pro
Joined: May 2003
Posts: 593
Likes: 0
From: London England
Oil and fuel technology alone is light years from the 1960's. Combine that with improvements in replacement piston and ring design, engineering tolerances and manifold and carb design and even though the block may be from 1969, everything else isn't.
