Freeze Plug the PCV hole!!!!
- Thread starter stangnutlx
- Start date
The Shape
Founding Member
because i used breathers on Valve covers instead of using a PCV valve.... works better than a PCV valve!!
18mustangs
New Member
stangnutlx said:
crapola I'm afraid that the physics are against your position. You've created a passive crankcase ventilation system which doesn't really ventilate the crankcase at all, it just equalizes the crankcase pressure with the pressure in the outside\engine bay. The PCV or POSITIVE crankcase ventilation system not only prevents excess crankcase pressure (when properly maintained with a new PCV filter, grommet, and valve at predetermined intervals), it actually ventilates the crankcase freeing it of the corrosive oil laden crankcase vapors prolonging engine life. I've got a lengthy write up on it if you'd like me to PM it to you.
Tim
Ed Curtis assembled the whole motor... he chose to go that route rather than run a PCV system.. Im still trying to understand the reasoning behind it but i havent had a chance to sit down with him and discuss it...
stangnutlx said:
Ed Curtis? I have heard that name here before right?
Did you tell him that this car was for track use only? To me that is the only somewhat justifiable reason to get rid of the pcv. I am still having problems with my pcv system, but I am not about to ditch it all together.
I would love to hear a professional engine builders reasoning for not running a pcv, even if it is for a track only car. If you do get an answer from Mr. Ed Curtis I would be very interested in hearing it.
If you do decide to actually cap the system off, I think the easiest way to do it would be to measure the hole, then call the local machine shops for an appropriately sized plug. Or just take the manifold to the machine shop and have them install it?
The pcv is designed to utilize the pressure differential between the pressurized crankcase and the low pressure (vac) of the engine intake to pull harmful by-products of combustion out of the crankcase.Nasty stuff like sulfuric acid and water. A secondary benefit is to help seat the rings, but for most applications the effectiveness of this can be argued. The pcv output is routed to the intake charge for emissions reasons.
18mustangs; How dare you tease us with information, and then not post it.
If it is difficult to post, I would like to receive in a pm as well!
Good luck
jason
So far still no answer from Ed, im thinking the reason he did this is because it is an all out race motor with a large cam .594 exh lift. I will use this car on the street occasionally. BUT im still waiting to hear for myself....
stangnutlx said:
What kind of duration numbers do you have on the cam?
I would think duration to have more effect on pcv operation than lift
I hope my comments about Ed Curtis did not offend. I am just curious why this would be done.
If only plugging the hole and just slapping on breathers were that easy. You are most likely going to have smoking/leaking breathers. And if the engine can vent those vapors correctly, they will find another way out of the engine. IE: through your gaskets, specifically the rear main.
18mustangs
New Member
vristang said:18mustangs; How dare you tease us with information, and then not post it.
If it is difficult to post, I would like to receive in a pm as well!
Good luck
jason
No problem Jason, i just figured people were getting tired of my anti-breather soapbox! This is really EFI specific, but many of the same principles also apply to carb cars with the closed crankcase, specifically what you mentioned about positively ventilating the harmful crankcase vapors.Tim
How the PCV system works
One an EFI engine and some later carburated engines, the PCV (positive crank case ventilation) system draws air from the crankcase into the intake stream and into the combustion chamber where it is burned in order to reduce emissions. This system does more than reduce emissions, it positively ventilates the crankcase prolonging engine life, whereas running a breather cap system even with the PCV valve capped or filtered to the outside is a passive system rather than a positive system like the PCV, and is not as efficient at ventilating the crankcase as the PCV system as our newer emissions friendly engines do not have road draft tubes like older muscle cars did in order to create the positive ventilation effect that the PCV valve does. Also remember that the PCV system is an emissions component, and if it is deleted or changed some states may fail the visual portion of your emissions test.
Why not to run a filtered breather cap
One should never run a breather cap on an EFI engine with a functional PCV system (with the oil filler neck capped or connected) as the breather cap allows unmetered air from the engine bay to enter the crankcase and then the intake charge via the PCV valve which creates a lean condition. This lean condition may cause detonation\pinging (a common problem with SN95s in stock form) to occur, and it is important to note that detonation is not always audible so you may not know that you’re pinging. This lean condition is created because the PCV system draws fresh metered air into the crankcase via the oil filler neck hose in order to replace the oil vapor laden air that the PCV valve drew out of the crank case into the intake charge. This is a 1:1 swap so the air fuel ratio is affected, and prevents a vacuum from forming in the crank case when the PCV valve draws the air out of the crankcase. If one runs a filtered breather cap the the intake charge still has 100% if the intake charge’s air as no air was diverted to the crankcase, and now the additional air from the crankcase is added to the intake charge leaning the air fuel mixture.
Capping the filler neck hose
One should not cap the oil filler neck to throttle body PCV hose in order to reduce oil in the intake charge as that hose is bi-directional (with the correct non breather oil cap or even with a filtered breather cap). The PCV system draws fresh metered air into the crankcase in order to replace the oil vapor laden air that the PCV valve drew out of the crank case into the intake charge. This is a 1:1 swap so the air fuel ratio is not off and prevents a vacuum from forming in the crank case. If the PCV valve cannot keep up with the pressure inside of the crankcase the extra pressure can be relieved via the oil filler neck hose. Capping off the PCV oil filler tube with the proper oil cap prevents the extra crankcase pressure relief, contributes to a vacuum in the crankcase, and contributes to a lean condition as no air is diverted to the crankcase from the intake charge while air is added to the intake charge from the crankcase. Capping the oil filler neck with a filtered breather cap allows unmetered air to enter the intake charge from the engine bay via the crankcase, through the PCV valve.
One Possibility for filtered breather caps
If one is dead set on running breather caps, you should cap off the oil filler neck\TB PCV connections and put a small breather on the PCV valve (capping off the intake vacuum ports that the PCV hose used to lead to) as well as on each valve cover. This system is not as efficient as running the PCV system but does prevent excess crankcase pressure from blowing out gaskets and causing oil leaks. This is not recommended as this is not a positively vented system, it only relieves excess crankcase pressure and doesn't ventilate the crankcase with fresh air extending engine life.
Ed told me itll keep oil out of the intake and not to worry about anything.. He also said it wont smoke out of the breathers just work more effeciently... As far as the duration on my Cam i cant find the cam card right... I emailed Ed on it cause its his grind....
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