Vent Filter for Valve Cover??

[opisopus]

Just curious what the purpose of a vent filter is? Saw it while I was browsing parts on GoPowerSports. I’m doing a few upgrades to my Coleman 196cc engine (Heavy valve springs, open air, new exhaust etc...). Would it be beneficial for me to have one? Thank you

 

[Flyinhillbilly]

I use a big K&N on my kart with vent hoses from the side cover to the gutted valve cover. My way of thinking says that if it’s not building pressure on either direction of the stroke that it should free up some power.

 

[JTSpeedDemon]

What he's saying is that if the vent can release internal pressure, it robs less power, getting more to the wheels.
I'd do it.
P.S - Briggs already have breather vents built in.

 

[Snaker]

That is the equivalent of a crankcase vent, but some engine designer found it convenient to be located where its at. Same internal open space. Normally its plumbed to the air cleaner box and mixed with the intake air.

If you removed the airbox then it obviously cant go there anymore. Technically the vent hose doesn't need a filter, just route it out of the way. In racing it is usually required to be run into a catch can.

A Filter is nice to keep dirt and bugs from plugging the hose.

 

[Hellion]

...A Filter is nice to keep dirt and bugs from plugging the hose.

I never thought much about it, but without the filter, it may actually suck dirt in, no?

Other engines like the old Briggs have a combination crankcase breather and a one-way diaphragm. It blows out but nothing gets sucked in because the crankcase vacuum seals it.

You actually need that filter.

 

[Snaker]

I actually did some testing on that in the past. I ran a extended vent hose into a cup of water. There was a lot of turbulence with the water bubbling hard and spilling over but the water didn't go up the tube much.
What you have is the difference of crankcase volume between when the piston is at top dead center vs. at bottom dead center.

 

[Hellion]

Well water is one thing and fine airborne particulates are another.

Tons of ruined engines out there that died an untimely death because of poor or zero air filtration.