Moto gp racers use purpose pumps to create vacuum in the crankcase and the latest Ducati R bikes have such pumps. Why do they have these if it is obsolete technology and means loss of power?
It dont believe its obsolete technology in any way .... the crankcase has to vent blowby ...
Breathers are dealing with inadequate crankcase atmospheric volume
Where the crankcases are often sized just big enough to hold the flywheels , camshaft and a small oil sump .
The compact design of a motorcycle crankcase comes at a cost .
The pistons down stoke can significantly decrease crankcase volume .
Adding a timed angle of venting... through the camshaft ... on the pistons down stoke is one approach.
Adding the primary case volume to the crankcase volume
Was just another approach
Where increased volume already available was utilized in a different way .
The pistons downstroke has less pressurizing effect on a larger volume .
But gp racer are probably using vacuum , I'm guessing for a totally different reason .
Cyclic Crankcase pressure is a reaction to loss of volume as the pistons come down .
The stored pressure is returned on the pistons upstroke... there is no energy loss except for friction
But the pressure wave , i think , acts like a flywheel.
Decreasing crankcase pressure probably decreases any flywheel effect ... letting the engine rev more quickly ?