Catch can different flow design

[Ta2272]

Hey guys i am about to start construction on the catch can for my race car, It will follow all the rules to cams specs 2 lt etc etc, i have a different idea one which i havnt seen before for a catch can, I am just pondering if anyone else has thought of this or if it can cause problems.

I am proposing to have 3 holes in the catch can 2 at the top 1 at the bottom, the two on the top recieve, the tapper cover breather, and a breather for the can itself

the single on at the bottom of the can is for the the crank case breather.

In turn when oil gets spat out of the motor due to blow by ( and it does spit out a fair amount of oil) it will then eventually seep back into the crank case breather hole.

Below is a quick diagram of the proposition, (excuse my paint skills)



The reason for doing this is that i can only see positives, saves oil, empty's itself, etc etc.

The thing i am wondering is are there any negatives from this setup??

thanks guys

[Disturbed1]

mates done it on his rb26... they are notorious for blow by... N$S captures about 1.5 litres (almost full can) within 30 min of hard driving... for some reason he likes to pour it back into the engne manually... although my mate is in his run in period for his fresh motor he isnt haveing any problems so far and i doubt he would take any risks on a 40 k engine

[Ta2272]

Yeh i just thought there may be a posability, that having oil flow back in the opposite direction through the crank case may have a negative affect.

[oldcorollas]

The thing i am wondering is are there any negatives from this setup??

thanks guys

perhaps moisture condensation and the water running back into the sump? there will always be moisture coming out of the motor.... hopefully it will stay as vapour until it leaves the catch can tho. (but if catch can is cold, then it may condense to water

[Ta2272]

that is the possabilty i am talking about, though the can is on the side of the extreactors and i doubt the can will ever be cold,

However this is a valid point, how much moisture could come of this, is it worth creating an original catch can because of this possibilty, surely there cannot be that muc moisture

[Ta2272]

After thinking about it a bit more there would the minimal amount of moisture from that proccess, and if moisture was to develop the amount that would develope, would quickly be turned back into air moisture when going back into the motor with the oil operating at temps over water boiling temp

Do you agree with that?

[roadsailing]

the stuff that gets into my catch gatorade bottle looks like sludgy shit, i'm glad its not going back into the engine.

just put it into a normal can, then you can have a look at it and decide if you want to tip it back into the motor or not.

[Ta2272]

i presume the sludgy looking stuff would just be a mixture of exhaust gases and oil, reclycling this constantly would not be bad, as it is already existant in the motor.

[ONCE-NA]

The stuff in my catch can looks something like destilled oil, very clear and very thin with a slight oily smell. Is this normal for a healty motor?

[Rex_Kelway]

Rex has just scanned this thread and its responses, an by scanned He means what he is aboot to say may have been said.

Your problem, and it is a big one, is that it is still looks like essentially a sealed system. The whole idea of the PCV system is to allow the air that bypasses the rings out of the crank case so it doesnt build pressure.

Your idea is sound as long as it is not sealed. It must either vent the blow by air to atmosphere (catch-can) or allow it to be re-burned (oil/air seperator).

As an aside. Rex wouldnt re-use or drain the catch can oil back to the sump. IRHO its false economy.

[myne]

myne would like to say that the larger the sump return the more likely it is that it'll function better.
myne thinks that due to the *relative* low SPEED of the gasses from the sump rising, the oil will flow down fairly well. myne thinks that having a baffle in the middle of the catch can running vertically to about half way, seperating the PCV from the head's breather will work fairly well.

So you'd end up with something like this :


myne thinks that talking in the 3rd person is really stupid

[Screamn_Sleeka]

I think a problem u might find is that u will have pressure in the block, which will blow up that pipe and into the catch can, then u jsut have an oil filled can ready to blow all over your exhuast...
So manual emptying is safer.
Other wise its a good idea, i think the concept. I might do some experimenting with that

[myne]

That's why the return pipe is so large - so that the relative wind speed isnt greater than the force of gravity.As the can fills, the weight of the oil will reach a point where some of it can run down the sides of the return against the flow of the air.
The bigger you can make it, the more effective it'll be. Steel wool/whatever in the base of the catch can will help as it'll slow the mixture down enough for the oil to condense into distinct droplets.

Worst case, it fills as a normal can would and air perculates through it under load, but it drains under deceleration because there'll be very little in the way of blow-by during that.

[kingmick]

Hey guys i am about to start construction on the catch can for my race car, It will follow all the rules to cams specs 2 lt etc etc, i have a different idea one which i havnt seen before for a catch can, I am just pondering if anyone else has thought of this or if it can cause problems.

I am proposing to have 3 holes in the catch can 2 at the top 1 at the bottom, the two on the top recieve, the tapper cover breather, and a breather for the can itself

the single on at the bottom of the can is for the the crank case breather.

In turn when oil gets spat out of the motor due to blow by ( and it does spit out a fair amount of oil) it will then eventually seep back into the crank case breather hole.

Below is a quick diagram of the proposition, (excuse my paint skills)



The reason for doing this is that i can only see positives, saves oil, empty's itself, etc etc.

The thing i am wondering is are there any negatives from this setup??

thanks guys

cams specs you dont have to go back to the sump, so dont! you get moisture sucked in the filter when the system cools down so your better of just to empty it! even on dry sump setup i use a catch can not a return can!
you even get moister build up under the cap of a drysump tank, but the diffrence is we change the oil at around 500km. unless you have a really bad topping up problem there is no point putting the catch can oil back into the sump.

[30psi 4agte]

Have you searched this forum ,for this info ?? It was covered recently.

Are we talking about a 4age ??/ If so DO NOT drain back into block via the hole/pipe in the rh side of block !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The crank throws oil straight up into this pipe and can actually fill up the can !!