Catch Can Chapter 63

[Clump]

I know the catch can subject has been beat pretty well to death here, but...

I was watching Motor Week last night. On the Goss Garage segment he was discussing direct injection and intake deposits. His contention is that the deposits are not caused by GDI, but by low tension rings sticking and causing high crank-case pressure that forces oil through the PCV. He recommends a catch can, but says it won't do much for you if you drive gently.

Here's a link - http://www.motorweek.org/features/goss_garage/catch-can-oil-separator

FWIW I have a catch can on my car and I do tend to use the throttle.:shrug:

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[wildcatgoal]

It'll catch some oil and that oil will not go into the engine. That's good. Chapter complete.

 

[Higgs Boson]

A lot of the deposits are also from overlap situations when the piston pushes exhaust back into the intake manifold when the intake valve is open during some of the exhaust stroke. Coupled with oil on the cylinder wall it's going to get some poop in the intake runner and on the exhaust valve. Of course the port injected motors help keep that clean by spraying the valve with fuel and detergents before it opens (and DI engine do not).

I've used a ton of catch cans since around 1999 and none of them made a difference even though all of them "caught oil." There is a huge misconception that oil in the catch can means no oil in the intake manifold....the only way to eliminate it is by using open filters on your valve covers, which is smelly, or using a vacuum pump into a catch can with an open filter, which is smelly, but works great and can free up 20 or so HP. Passive cans are for the birds. Do it right or leave it alone, IMO.

And no, "something is better than nothing" is not true.

 

[apex15stangPP]

A lot of the deposits are also from overlap situations when the piston pushes exhaust back into the intake manifold when the intake valve is open during some of the exhaust stroke. Coupled with oil on the cylinder wall it's going to get some poop in the intake runner and on the exhaust valve. Of course the port injected motors help keep that clean by spraying the valve with fuel and detergents before it opens (and DI engine do not).

I've used a ton of catch cans since around 1999 and none of them made a difference even though all of them "caught oil." There is a huge misconception that oil in the catch can means no oil in the intake manifold....the only way to eliminate it is by using open filters on your valve covers, which is smelly, or using a vacuum pump into a catch can with an open filter, which is smelly, but works great and can free up 20 or so HP. Passive cans are for the birds. Do it right or leave it alone, IMO.

And no, "something is better than nothing" is not true.

This is always on my mind, blow/crankcase pressure by at speed with these cars is very high. I can fill and 20 oz catch can in 15-20 mins. G forces don't help with this. I've tried open filter( I don't mind smell) but them oil is all over the motor, the driver side is the worst. My question is does the factory setup act as a vacuum pump in higher RPM's?

 

[Higgs Boson]

This is always on my mind, blow/crankcase pressure by at speed with these cars is very high. I can fill and 20 oz catch can in 15-20 mins. G forces don't help with this. I've tried open filter( I don't mind smell) but them oil is all over the motor, the driver side is the worst. My question is does the factory setup act as a vacuum pump in higher RPM's?

no, there is no vacuum at high RPMs, crankcase pressure then just tries to push out any opening, this is why most high HP applications do away with the stock pcv system as it becomes a restriction.

look into a breather can instead of valve cover filters. there are some remote mount options with open filters and they have large capacities and baffles to keep the oil from escaping the filters. i have something like this on my C7. the big point is to eliminate the intake manifold entirely from the crankcase evacuation system equation.

 

[california special gt]

Just run breathers. Vent crank case and eliminate oil into intake track.

 

[rredd14]

I have yet to have oil drip off these breathers. They have been on for over 2500 miles. Also used the same type breathers on all my other mustangs without a single issue.

 

[invaliduser]

What do you cap the intake side with if you have the breathers on?

 

[Higgs Boson]

What do you cap the intake side with if you have the breathers on?

Vacuum caps

 

[rredd14]

What do you cap the intake side with if you have the breathers on?

The kit from JCP comes with caps and clamps.

 

[RockStang]

So glad I saw this thread. I am doing a Procharger kit and was going to get an expensive a$$ catch can. Going to try these breathers first. I live 5 min from JPC so I'll pop and and grab their kit.

Thanks all.

 

[Freedom]

can i get a link to a breather kit? I cant seem to google anything

 

[GT Pony]

This is always on my mind, blow/crankcase pressure by at speed with these cars is very high. I can fill and 20 oz catch can in 15-20 mins. G forces don't help with this.

I'd rather have that 20 oz in the can than in the intake manifold and into the cylinders.

 

[GT Pony]

BTW - running open breathers on the valve covers and doing away with the active PCV system probably doesn't evacuate the guts of the engine that well. Long term effect might not be ideal, as without an active vacuum on the crankcase it's possible some condensation and nasty blow-by products stay inside, especially if driven short distances.

 

[5ABI VT]

This thread amazes me.

The pcv system is far more valuable to a street car than a breather. There is significant amounts of combustion gasses and blowby that get past the rings and into the crank case. With no pcv guess where it goes? All over your internals and mainly into the oil destroying your oil REAL fast. Do you really want contaminants and dirty oil flowing through micrometer bearing clearances at 7500 rpm? No you dont if you care a little for your motor. Catch cans can help but arent perfect. They certainly can reduce oil buildup in an intake manifold. If you are running a catch can yes there is no Vaccum sucking from the crank case but there is a fresh air tube that does 2 things. 1. It allows fresh filtered air to enter the crankcase when pcv is sucking dirty air out. 2. Allows pressure buildup of combustion gasses/blowby to get pushed back into the intake to be drawn back in and burned.

forced induction a little different story but for NA run the pcv if you drive on the street. Leaving the factory pcv is better than a breather.

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