planeman01

I recently made a simple catch can out of pvc, brass fittings and steel wool. I put it all together and it looks pretty snappy...

Now i see that some of the catch cans for sale on the market have what ammounts to a valve cover breather on the can in addition to the in/in or in/out fittings and sometimes a drain.

I want to know why there is a air filter on the top of some of these catch cans. It seems to me that if you had a fitting for in/out, and then you put a breather filter on the top, you'd loose your vacuum drawing the gasses in and loose the whole effect.

please lean me cause i couldn't figure it out after reading up on it!

TIA

R

planeman01

up

Sketch_hs

i donno but i want to see pics of your DIY can

xtremeness101

my endyn catch can has a filter on it and it smokes when the car is warming up, dont know if it is suppose to do that but it has did that since the first day i ran my new engine?

iBrandon

normal for smoke to come out...

planeman01

i knew i should have taken pics of my can while i was making it....

i took a length of 2.5in abs (pvc pipe) 2 caps abs as well, steel wool, some plastic tubing, brass barbed fittings and a brass valve.

here's what i made:

i tapped one of the caps with 2 barbed fittings. i tapped the other cap with the brass drain valve.

i hooked up the length of tube to the bottom of the brass barbed fitting and secured it to the threads with a clamp. the tube is 3/4 the length of the pipe.

I stuffed the pipe with some steel wool that i stretched out a bit.

i capped the bottom off with the fitting for drainage installed.

the parts were assembled with regular pipe cement for abs pipes.

i can get a pic of the finished product and i can make a diagram if you want....


i know that this will work well but i want to know why some of the other designs have breather filters on the top or the side. seems to me that it wouldn't work properly....

R

planeman01

anyone else?

onefstek

I have my catch can hooked up to the valve cover and the back of the block, and also have a filter on top of the can.

planeman01

but whats the point of the filter on the top of the can? I'm trying to understand the physics of the damn thing and i don't see how a filter at the top would improve the performance of the can

94lsboost

In a setup such as mine, in which you run two ports from the back of the block to the catch can you need somewhere for the pressure to escape. The breather on top of the catch can allows the pressure to escape while the oil fals down into the can. Without a breather, you might as well leave the holes on the back of the block plugged, b/c you aren't relieving any pressure from the bottom end.

ProjectDarkBlack

The whole point of having a catchcan is to let the crank case pressure out, and be able to separate the oil from the blowby gasses. Having a closed catch can won't do anything.

ImportMotorSpec

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ProjectDarkBlack &raquo;</TD></TR><TR><TD CLASS="quote">The whole point of having a catchcan is to let the crank case pressure out, and be able to separate the oil from the blowby gasses. Having a closed catch can won't do anything.</TD></TR></TABLE>

Also, the filter on top isnt just a valve cover breather filter. It has atleast a 1" hole to let the pressure out. I know summit and jegs carry the filter.

MotorMouth

You need a close loop from the intake mani to one side of the valve cover. You also need an open breather from the opposite side on the valve cover.

For the block you need an open breather setup that allows for drain back similar to the endyn setup.

This function the best because inder any situation the engine is being vented.

planeman01

ok- that makes more sense i suppose...i'm working with the ghetto B20A motor out of the 3rd gen prelude. I don't have the luxury of the back of the block ports to vent the crank case like you other b series guys....with my high pistion speeds (not vtec but long stroke) i'm concerned aobut the pressures building in the case. I can vent the valve cover np but i'm at a loss on how to vent the crank case short of tapping the block and i'm not keen on doing that on my freshly built block (wiseco pistons crower rods)....

MotorMouth

Without a lcear knowledge of the block, the best advice to give you is: Adapt the black pcv box on the back of the block to function as an open breather. You could probably tap the oil pan, similar to a turbo drain to allow the oil in the can to return to the block.

Goodluck, let us know what you do.

planeman01

my motor dosn't even have the black box on the back of the block...

tapping the pan sounds like a good idea....i'll look into that....THANKS!

hotboxedcrx

Tapping a return into the oilpan is a good idea, however you should be aware that the blowby gasses and oil returning to the oil pan, are not pure oil... you will be draining an oil/gas mixture back into the oil pan. This is not good becasuse you will degrade the quality of the oil.

This solution is maintenence free. If you had a seperate catchcan to hold the blowby gas... you could empty it and remove the contaminates from the system.

rmcdaniels

You should be able to just vent the valve cover, there are a bunch of big passages from the crankcase through the head. I think the bigger problem with running a catchcan with an open breather is that you get rid of positive crankcase ventilation, so the harmful combustion byproducts that would normally get sucked out of the crankcase now stay in there and do bad things to your internals. One solution is to use a venturi with a check valve in your exhaust to suck crankcase gases into your exhaust, this will also create a vacuum in your crankcase, potentially improving your performance.

http://store.summitracing.com/...w=sku


http://store.summitracing.com/...w=sku