snaab wrote:Sorry to jump in late on this, but I have a genuine question. Both serious explanations and Julian's explanations are welcome.
Like Tallen says, do you really want oil that contains HC and CO recirculating? What they taught us at school is that car oil has become cleaner thanks to efficient removal of blowby gases. It seems counter to my armchair engineer logic that oil, that has been blasted by said gases if passing through this filter, is placed back in the system.
Furthermore, it seems like the amount of oil returned would be negligible, and that where you are wasting oil is really just in the lubrication of the cylinder walls.
Mr Kleen wrote:
snaab wrote:Like Tallen says, do you really want oil that contains HC and CO recirculating?
there are turbo cars running around with hundreds of thousands of miles on them that don't have catch cans. they seem to be doing OK.
I would only worry about a catch can (separator, whatever...) if I had a very
large aftermarket turbo running much
higher boost then stock.
Hey, I make good posts sometimes!
I can understand the reasoning behind you not wanting to throw the oil back into the engine, but look at this from the other side, a built car on the track. Built motors are looser than normal motors to allow for the expansion of the (forged) pistons. This is what causes that diesel like sound when they first start up. Blow-by occurs when air and moisture are forced past the rings into the crankcase. Since in a built motor, things are not sealed up tightly till they warm up, they get a ton of blow-by normally. As Gabe pointed out, running higher boost pressures also increases blow by. The reason that you would want that oil returning, again using the race car analogy, is because you are usually only running oil for a race or two, so you don't care about the HC and CO that builds up. It's going to get changed out after this race anyway
What is important is that you don't run out of oil on the race trace, which if you don't keep all the oil you can, will happen. Catch cans are great for street cars (I run one
, but for race cars, you really need something like this.