Catch cans catch stuff

[tinkerbell]

use fuel foam to baffle your catch cans!!!

v.good call - got a link?

[BlackDC2]

v.good call - got a link?

nope, but you can buy it at revolution race gear, they come in little blocks.

one block could probably fill up to 4 smaller catch cans or 2 larger catch cans.

think i paid about $15 for a block.

[Wlee2]

constantly? i.e. WOT???

nah, most of the time the throttle plate is closed isnt it?

which is when highest VAC is in IM, so that is the VAC source for the PCV system.

the intake air provides a source of clean air, as it may end up in the combustion chamber...


not sure what you are talking about?


but the pressure in valvecover is higher due to being attached to the intake manifold, isnt it?!

HUH if its attached to the intake manifold via moving air it will cause a vacuum!


the valve cover has vacuum via the intake manifold.

Umm contradicting yourself above there tinks?

simple.

(except maybe at WOT, which is when the PCV valve CLOSES anyways)

higher presssure? vacuum? wha?

[tinkerbell]

NB - just realised ALL my comments apply to non-forced-induction engines only...

[Wlee2]

NB - just realised ALL my comments apply to non-forced-induction engines only...

actually if its forced induction we remove the hose that goes from intake arm to the Valve cover because it will just force air into the valve.. and just run a mini filter.. and plus u dont wanna loose precious PSi when it doesnt go into the intake manifold =P

my comment only works for NA cars when the movement of air from high pressure to low pressure causes vacuum in the intake arm as well as the intake manifold same source similar vacuums..

[tinkerbell]

is the crank case connected to the air intake manifold? yes.

is the crank case connected to the air intake pipe? yes.

is the vacuum in the air intake manifold higher than the air intake arm? yes.

then the air enters the rockercover/crankcase from the air intake pipe, air flows throughout the engine and it is ingested into the intake manifold via the PCV valve...

doesnt it?

(except at WOT when the PCV valve closes.)

[tinkerbell]

actually if its forced induction we remove the hose that goes from intake arm to the Valve cover because it will just force air into the valve.. and just run a mini filter.. and plus u dont wanna loose precious PSi when it doesnt go into the intake manifold =P

my comment only works for NA cars when the movement of air from high pressure to low pressure causes vacuum in the intake arm as well as the intake manifold same source similar vacuums..

air still goes from higher pressure area to a lower one... doesnt matter how 'similar' the pressures are, the manifold vacuum (created mechanically BY the pistons going up and down) is always going to be higher.

[Wlee2]

is the crank case connected to the air intake manifold? yes.

is the crank case connected to the air intake pipe? yes.

is the vacuum in the air intake manifold higher than the air intake arm? yes.

then the air enters the rockercover/crankcase from the air intake pipe, air flows throughout the engine and it is ingested into the intake manifold via the PCV valve...

doesnt it?

(except at WOT when the PCV valve closes.)

you have lost me tinks.. ... the intake manifold creates its vacuum the same way as the intake arm does it not? when the air moves it shifts from high presssure to low pressure causes external sources to try equalize the change by bringing more air particles..

[Wlee2]

are we just arguing the same bloody point?

[tinkerbell]

my thinking is that the pressure in the manifold is higher due to the throttle plate being partially closed.

is that wrong?

why is the OEM set up like that?

[Wlee2]

ok..

1. we are i think arguing the same point
2. higher Vacuum = Low Pressure!!!
3. high pressure is llike 1 atm Vs 2 atm.. 2 atm of pressure is higher than 1
4. Vacuum as you call it is whats caused when a higher pressure moves to lower

vacuum is only relative to another


and i would lilke to think that even if the plate is closed that air is still moving through the intake arm since our cars still has to idle.. and that still needs air..

[tinkerbell]

im going to stay out of this for now.. since me and tom already had this discussion =P..

but if the rocker cover is sucking in and lets say what chi said the gasses is going into the engine before it goes near the catch can? then why did it catch something?
.

it was attached to the engine, there was flows of vapour laden gases, there would have been settlement of vapours in the catchcan...

the "why did it catch something" is flawed logic...



air flows from the intake arm -> rockercover -> crankcase -> PCV valve -> intake manifold -> combustion chamber -> exhaust

do you disagree with the above statement?

[ChargeR]

ok..

1. we are i think arguing the same point
2. higher Vacuum = Low Pressure!!!
3. high pressure is llike 1 atm Vs 2 atm.. 2 atm of pressure is higher than 1
4. Vacuum as you call it is whats caused when a higher pressure moves to lower

vacuum is only relative to another


and i would lilke to think that even if the plate is closed that air is still moving through the intake arm since our cars still has to idle.. and that still needs air..

I think this discussion would go a little better with a few pictures and less non scientific wording muddying up the issue.

I have a question for you tinkerbell: Why does the PCV close at wide open throttle, I would have thought that under this condition cylinder combusion pressures would be highest and hence blow-by will be significant and this pressure will require venting? Or are we assuming that blow-by is not significant unless your motor is shagged?

[tinkerbell]

i actually have to go, sorry

[tinkerbell]

I think this discussion would go a little better with a few pictures and less non scientific wording muddying up the issue.

I have a question for you tinkerbell: Why does the PCV close at wide open throttle, I would have thought that under this condition cylinder combusion pressures would be highest and hence blow-by will be significant and this pressure will require venting? Or are we assuming that blow-by is not significant unless your motor is shagged?

highest combustion chamber presasure means you DONT wantr any oil vapours as thes lower octane...

BOOOOM!

that is why the PCV valve is tehre - to SHUT at WOT so no oil vapours get into the intake manifold...

sorry - gotta go

maybe discus 'race' vs 'road' PCV's and why mugsee's in between attempt is less than ideal currently?