Catch Can on my Race car...

[Ta2272]

Hey guys i have a few questions, when i bought my datsun 1600 track car, it had a dodgy catch can, i have pulled it out and about to create a new one.

The hoses which lead to the old can were block breather and tapper cover breather.

However my dad had a few ideas which we woudl like to investigate before we select how to make the catch Can

1) Block off the block breather hole, only leaving the tapper cover one. ( wont this be a negative why would the block be there in the first place.)

2) Keep the crank case breather but run it to the bottom of the catch can so when oil spitts into the can it then can drip back into the block through its exiting route. ( for some reason i dont like this idea)

Can you please give me opinouns on these setups, what are the negs or positives about them. so i can then move onto a proper setup

Jason, thanks for you time guys.

[mullett]

I'd keep all the breathers you can get man, it's all a good thing. As for draining the oil back, I wouldn't. Often when you catch oil in a catch can, it ends up contaminated with water and other junk (not sure how). For the cost of a few ml of oil, put fresh stuff in Just go to AutoOne and get a $50 china catchcan, T-peice the two hoses to one of the inlets and put the other to a breather or filter...

RM.

[ed]

if its for cams events, dont they specify a sump return? plus minimal mumber of litres also?

cheers
ed

[takai]

No, for CAMS events you dont have to have a sump return. However, you must have a minimum catch can size. The minimum for U2L cars is a 2L catch can (rules out the $50 bling jobbies), and the minimum for O2L is 3L catch.

[stradlater]

what about if you have your breather fed straight back into your inlet?

[gemtoy]

I would not run the breather back into the intake. The last thing you want on a race car is the oil mist going back into the engine. You want clean air and good fuel only into the engine. My race car has a catch can with a sight tube on it. After each event I check the level and if I ever need to I empty it. I put a lever tap on it and it takes a minute to drain.

[stradlater]

I know you shouldn't do it, but I was wondering if you would be allowed to not have a catch can.

[Ta2272]

No you cannot just have it recurculating as i said my engine spits out a shit load of oil into the can every race, 250ml maybe.

Yeh i agree i just need to get one made.

Does anyone else know about the sump return setup, for some reason it just seems like an easy opening for sunk to get into the system.

Jason

[ed]

google crankcase breather designs...
heaps out there

also - i think cams only requires 2 or 3l catch cans for those breathers vented to atmo?

Oil Catch Can – (SR302.6 Page 15)
If the vehicle is fitted with crankcase breather/s discharging to the atmosphere it must have fitted to such
breather/s an oil-trap container complying of at least two litres (for vehicles of under 2000cc) or three litres (for
vehicles of over 2000cc).

[monkeymajik]

You want it as free flowing as possible.

[takai]

google crankcase breather designs...
heaps out there

also - i think cams only requires 2 or 3l catch cans for those breathers vented to atmo?

Oil Catch Can – (SR302.6 Page 15)
If the vehicle is fitted with crankcase breather/s discharging to the atmosphere it must have fitted to such
breather/s an oil-trap container complying of at least two litres (for vehicles of under 2000cc) or three litres (for
vehicles of over 2000cc).

Yeah, but a lot of the scrutes will interpret that as even if it is a drainback system. Because they see the fact that the breather is discharging to atmosphere through the can.

[dave368]

It should be noted that the under 2l and over 2l rule actually only applies to swept volume, not including capacity multiplers (e.g. supercharged 2lt = 1.7x2000cc = 3400cc).

Cheers,
Dave

[30psi 4agte]

TA2272: What engine are we talking about? I know you have a datto 1600 but whats in it
?

[takai]

It should be noted that the under 2l and over 2l rule actually only applies to swept volume, not including capacity multiplers (e.g. supercharged 2lt = 1.7x2000cc = 3400cc).

Cheers,
Dave

I think again that depends on the scrute at the time Dave. Although none of it matters now with the whole targetted scrutineering crap.

[1jzracing]

The idea of the drain back is that if your engine starts to get a little blow-by happening which race cars tend to do then the sump cant get robbed of oil and you dont get oil painted all over your engine bay - you need as much oil as possable in the sump to combat surge

Run as many breathers as you can (from the block too) into the side of a round tank at as much angle as possable then run a drain from the bottom to the sump preferably below the oil level so blow-by pressure cant go up the drain pipe and stop the oil from draining freely, put a little breather filter on top. This way the blow-by and oil mist swerls in the tank throwing the oil out to the tank wall and draining back to the sump and the clean blowby exits the filter

i used a piece of 100mm alloy tube about 300mm long with caps welded on each end, the bottom one a bit cone shaped

ive run this on my sports sedan for a coulpe years and never get any oil out the top even after some engine damage and bad blow-by