Dragsteer

Maybe someone will know...

On n/a engine, is better to connect oil catch can to inlet or to atmosphere?

I know that for air filter and engine top is better that oil dont go there, but some people told me that must be connected on inlet because inlet sucking air from oil catch can and help oil vapour better going out.

tabetha

What you were told is not the best engine power wise.
I would vent into a catch can, with the catch can vented to atmosphere through baffles.
Any oil/vapour going into the engine will lower the potential of that fuel, this is why the engines even N/A always have breathers vented to atmosphere, ther eis less blow by gasses on na but they do still produce them, the original set up breathing in the fumes is just for emissions reasons and does hinder power production, especially if modified.
tabetha

Dragsteer

Thank you. I had in my mind that you can give good answer.

So you will put oil catch can which is not connected to inlet (air filter) ?

Can I just leave oil breather pipe in standard air box (air box with filter but not connected to inlet) and leave air filter (k&n) alone without oil breather hose ? I will put oil breather pipe in old air box just to prevent dirt getting into pipe.

so will not be problems with oil vapours ventilation,cranckshaft ventilation or oiling the valves or something?