Remove the PCV system for performance?

[Sprucegagt]

Originally Posted by SpyhunteR

which is why I routed it into the atmosphere.

This argument is absolutely stupid. To be quite honest I've seen many cars where it was disabled, and to where they were not.

I know on my car if I had it hooked up N/A or boosted, in time the oil build up would be rediculous to the point where the intake ports would be smaller from all the crud. Just so damn dirty.

Agreed. In the end we are talking about a street driven vehicle that still needs to pass emissions. Taking the PCV system out is simply not an option.

Anyway it you really wanted to go all out. You would add a reed valve to each header collector and run a line from each valve to a breather on each valve cover. Then again to get the most good from this you would be running low tension oil rings as well.

[xonelith]

Originally Posted by Sprucegagt

Agreed. In the end we are talking about a street driven vehicle that still needs to pass emissions. Taking the PCV system out is simply not an option.

Just to add to the emissions comment. At least in Ontario, as long as I'm not selling the car (just renewing plates), there is no visual inspection (or at least it's a 'loose' inspection).

I passed with the breathers. From what I have read on the internet (take that for what it's worth), removing the PCV system actually helps with tailpipe emissions (kinda makes sense since alot of crap is being vented other places than at the tailpipe).

I also think that 'street driven' vs 'race driven' is too general. Modified vs unmodified is where I see benefits in modifying the stock PCV system. Yes, my car is street driven, but I would say it is 'performance oriented'.

Personally I don't like it, due to the smell. I'm still in a tossup since I see the benefits of both arguments, but I think using breathers (or the catch can from Jegs) is not the way I will go. Either stock, or a true catch can setup.

Finally, from what I can see, no performance gain can be had. However, I do think that a longevity issue comes when attempting to rid your engine of contaminants. I do think this is more prevalent in a boosted setup though due to the additional pressure.

-xon

[Gt00]

I can't see there being any significant gain from this , i doubt it's even worth the trouble ....

[bigstribs]

wow i had to take a nap after the first page

[Vegeta]

So there is no performance gain to be had by applying vacuum to the crankcase.

[Sprucegagt]

Originally Posted by Vegeta

So there is no performance gain to be had by applying vacuum to the crankcase.

I detect a hint of sarcasm. Vacuum is a good thing, you just need more than the PCV can provide. Then again, I'm sure you already know this.

[Vegeta]

http://en.wikipedia.org/wiki/PCV_valve

I ran a filter between my pcv and the intake. Collected quite a bit of oil, and other nasty ****. It smelled awful as well. Burning this is going to increase tailpipe emissions, but will pollute more overall when its vented to the atmosphere. Give a hoot, don't pollute. No breather on the PCV. You can put breathers on the valve covers if you want. I prefer to keep it all stock other than that filter.

I used a Campbell Hausfeld or equivalent water separator meant for an air compressor. Replaced the filter with steel wool, so that the vapor would hit it and collect at the bottom.

Gas milage improved, performance improved, start up and overall running quality improved. I could fill it up in 60 miles highway driving in the winter. Thats a 3.4 DOHC, which is worse than a 3400 for sucking up oil and contaminates from the crankcase.

Pulling vacuum on the crankcase helps seal the rings as well, so there is less blow by when you have the PCV hooked up (or a vacuum source of some type )

Oh, one more note. Don't run a colder stat. It makes the situation in your crankcase much worse.

[KPimm]

All I can say is wow!! I just came across this thread and I can't help myself but to comment.

1) There should be no need to remove the PCV system on a street or even a street/strip vehicle. The engines vacuum is causing the valve to open which is drawing the blowby contaminants out and into the intake. Right, you've beat that horse enough, but what I ask you both is how much vacuum is the engine producing at WOT when you want the maximum power. Oh yeah, no vacuum at WOT. So that means the PCV should be closed and the A/F mixture is not seeing any crankcase "crap" until the throttle plate closes enough to produce vacuum again. This is why basic race engines use breather filter WITHOUT a PCV. That allows the pressure and blowby contaminants to escape freely without the need of engine vacuum, since they are at WOT for long periods of time.

2) If you really want the best setup for power, we need to develope a dry sump oiling system. This puts a good amount of vacuum on the crankcase to remove the blowby contaminants and help seal the rings better. OK, I know this is not the most ecconomical solution, but there are even more advantages to a drysump system than I've listed. Why do you think top level race engines use them. Also what does the new ZR-1 Corvette engine have?

3) Another option is to try an exac system which again uses no PCV valve, but is plumbed to the exhaust. You need to use a one-way valve to prevent the exhaust from coming back into the engine and it must be tapped into a low pressure spot in the exhaust. I don't know if this kind of system works on street cars, but I have seen it done on race cars before. I will warn you (if anyone is thinking about trying this) I have seen these systems start a siphon of engine oil into the exhaust, which should be obvious, but it's bad.

[BenGTH.O.]

It will cause the exhaust to smell horrible and decrease fuel mileage also.

[mr_eh]

i stopped reading after the first reply.

anyone ever heard of a catch can? it prevents the oil from recirculating...

so theres no harm in losing the egr

[cardude007617]

i dont know why this thread is still going on... everyone has their own opinions

[AaronGTR]

Originally Posted by mr_eh

i stopped reading after the first reply.

anyone ever heard of a catch can? it prevents the oil from recirculating...

so theres no harm in losing the egr

It's pretty obvious u didn't read the thread... because we had all kinds of discussion about catch cans.

[grandam01]

Soo I am proud to post on this, looks like some really interesting discussion, buttt... I will add anyways as though I feel like the lemming who has to blow himself up for the rest to survive. haha.

Many if not all race apps I have seen don't use PCV valves, when you are building a motor with performance parts you will vent the gases away from the motor, besides it is also hotter air sooo... not saying definately will do but possibly can reduce the amount of KR warmer air means warmer intake temps, kind of killing the point of having a CAI yeah?? I understand it needs pressure and you cannot simply say look at a car with no pcv versus a car with the pcv especially when it comes to a newer computer controlled car, you should tune for the mods you do, my old 76 camaro with the 350 v8 I pulled the pcv and put breathers on it, it actually ran smoother, the pcv was an emissions control item, on that same 76 camaro from what others had researched is if you pull the intake mani off and car and go with a new intake setup and a 750 cfm carb you get a whole mess of power back, the egr and pcv system killed the performance.

Nowww yes gm has done a lot of testing but their concern is reliability and economy not performance, not saying milzy is one hundred percent correct but until PROFESSIONAL race ENGINEERS stop designing engines without either the egr or pcv then I will continue to look for ways to delete them myself as well.

But everyone is entitled to their own opinion. have a nice day everybody.

[KPimm]

Originally Posted by grandam01

Nowww yes gm has done a lot of testing but their concern is reliability and economy not performance, not saying milzy is one hundred percent correct but until PROFESSIONAL race ENGINEERS stop designing engines without either the egr or pcv then I will continue to look for ways to delete them myself as well.

I'm telling you, removing the PCV and or EGR is completly useless and a waste of time and money for a street vehicle that does not see long WOT durations. And for your information I am an engineer for Gillett-Everham Engines .

[MilzyZ34]

Originally Posted by KPimm

All I can say is wow!! I just came across this thread and I can't help myself but to comment.

1) There should be no need to remove the PCV system on a street or even a street/strip vehicle. The engines vacuum is causing the valve to open which is drawing the blowby contaminants out and into the intake. Right, you've beat that horse enough, but what I ask you both is how much vacuum is the engine producing at WOT when you want the maximum power. Oh yeah, no vacuum at WOT. So that means the PCV should be closed and the A/F mixture is not seeing any crankcase "crap" until the throttle plate closes enough to produce vacuum again. This is why basic race engines use breather filter WITHOUT a PCV. That allows the pressure and blowby contaminants to escape freely without the need of engine vacuum, since they are at WOT for long periods of time.

2) If you really want the best setup for power, we need to develope a dry sump oiling system. This puts a good amount of vacuum on the crankcase to remove the blowby contaminants and help seal the rings better. OK, I know this is not the most ecconomical solution, but there are even more advantages to a drysump system than I've listed. Why do you think top level race engines use them. Also what does the new ZR-1 Corvette engine have?

3) Another option is to try an exac system which again uses no PCV valve, but is plumbed to the exhaust. You need to use a one-way valve to prevent the exhaust from coming back into the engine and it must be tapped into a low pressure spot in the exhaust. I don't know if this kind of system works on street cars, but I have seen it done on race cars before. I will warn you (if anyone is thinking about trying this) I have seen these systems start a siphon of engine oil into the exhaust, which should be obvious, but it's bad.

1. Actually a PCV flows more at high speed/low vacuum than it does at idle with high vacuum. Here's a site where I found some info to support this ... http://filtercouncil.org/techdata/tsbs/94-2R1.html .

2. Yes, we could run a dry sump system, and i agree this would be a good mod, but I would guess that spending the amount of money it would take to put one together would be too much for most people here.

3. Yeah that's another way drag racers ventilate their crankcase.

P.S. - I am also an engineer

[grandam01]

Well I am just saying ya kno I understand that most applications that use it are definately seeing a lot more wot than myself being a mostly stock ga owner. I am not an engineer yet, 4 more years till I complete this damn Mechanical engineering program good thing is my senior project I get to design and build a small engine indy car.

Anyways back on topic I will say that I am far from being any sort of expert or knowledgeable source now but hey to each his own, I know that some people prefer one thing and others prefer another.

[AaronGTR]

Originally Posted by MilzyZ34

1. Actually a PCV flows more at high speed/low vacuum than it does at idle with high vacuum. Here's a site where I found some info to support this ... http://filtercouncil.org/techdata/tsbs/94-2R1.html .

Yes well, while that may be true, it still doesn't mean that running an open pcv is better than having it routed to the intake. If you read that entire article it very clearly explains the reason why the pcv flows more at WOT. It's because there are more blow by gases that need to be removed at WOT than at idle, so the PCV valve is designed to adjust the flow rate according the the amount of evacuation needed. You neglected to mention that.

You also have to take into account how many of these cars are street driven and do not spend all their operating time at WOT. Absolutely none, as has been mentioned several times already. Given that fact, and the info above, it is still clearly better to leave the PCV system intact as designed by GM.

[MilzyZ34]

Originally Posted by AaronGTR

Yes well, while that may be true, it still doesn't mean that running an open pcv is better than having it routed to the intake. If you read that entire article it very clearly explains the reason why the pcv flows more at WOT. It's because there are more blow by gases that need to be removed at WOT than at idle, so the PCV valve is designed to adjust the flow rate according the the amount of evacuation needed. You neglected to mention that.

You also have to take into account how many of these cars are street driven and do not spend all their operating time at WOT. Absolutely none, as has been mentioned several times already. Given that fact, and the info above, it is still clearly better to leave the PCV system intact as designed by GM.

I think I did mention this earlier in the thread actually, when I said how at higher rpm, this increase in blowby gases would cause more pressure in the crankcase, which would then be released from the breathers on the valvecovers.

[KPimm]

Originally Posted by MilzyZ34

1. Actually a PCV flows more at high speed/low vacuum than it does at idle with high vacuum. Here's a site where I found some info to support this ... http://filtercouncil.org/techdata/tsbs/94-2R1.html .

I'm sorry, I thought the PCV operation was similar to a vacuum controlled EGR valve. I should have looked that one up first .

Either way though, that article did not help your side of the debate at all. It clearly says that no performance is gained and that it can cause premature internal wear/failure. I guess it just seems like a silly thing to do for a reletivly low HP engine that is not intended for all out race conditions.

[silvergtjrad]

Originally Posted by KPimm

Either way though, that article did not help your side of the debate at all. It clearly says that no performance is gained and that it can cause premature internal wear/failure. I guess it just seems like a silly thing to do for a reletivly low HP engine that is not intended for all out race conditions.

Case closed. It can be harmful to the engine internals, and there arent any noteworthy performance gains.