Why catch cans are used.Catch cans are used to stop oil from misting the inside of the intercooler and build up of slug.The oil makes a barrier between the aluminium there fore not cooling.The other issue is of octane reduction.Oil is terribly bad to mix with incoming air charge.By nature,oil is actually a octane reducer,so any oil vapours the turbo compressed air picks up on it`s way is effectively lowers the octane of your fuel you are using.This happened on my two suzuki rsr works 660cc twin cam four valves a cylinder.when I fitted a catch can and cleaned out the intercooler with degreaser,lots flushing out with water to get rid of oil and degreaser.you would be ammased by the amount of oil and sh*t that comes out.the little suzuki alto work motors need all the power you can pull from them 48kw 9000 rpm put only 654 kg.good fun little cars.so I have three turbo cars now.this is part extact from,Hot4s tech hand book.Good read .cheers.keep it clean,more power.
