Quote:
Originally Posted by tzei
Thread ressurected (sorry)
My q is about dry sump breather line non-return valve (or in line check valve - if you prefer).
I've looked thru some schematics about the whole ds layout but have't found any pics/text regarding that explains its purpose in a system (it might be due my poor English skills too  )
Care anyone please explain and educate me? |
Spooky, Just been fitting one myself!
You should have one (or more in my case, long story) breather going from the engine to the dry sump tank (usually to the top). It should be orientated such that air can blow out but not get sucked back in.
The purpose of this is to allow any positive crankcase pressure to vent to the dry sump tank rather than blowing the seals out.
However, it is costing the opportunity of the dry sump scavenge pump stages to reduce the crankcase pressure in the engine, and thus getting some extra 'free' power by reducing windage losses and piston blowby.
The purpose of the breather valve is to allow air out when the crankcase pressure is positive but not allow it back in when the scavenge stages are trying to reduce pressure.
At least thats the theory.
On my engine I have two breathers to the dry sump tank. One will have the check valve in and the other will have a restictor in to limit the amount of negative pressure because I don't trust the seals.
Hope that helps.