All Modern slow speed marine diesel engines now use the uniflow scavenging system with a cylinder head exhaust valve
Advantages of Uniflow scavenging
> Simple linear construction
> long skirt (for piston) not required
> Stroke length can be increased
> High scavenging efficiency
> Low grade of thermal efficiency
> Low grade of fuel can be burnt
> uniform wear of piston rings and liner
> less thermal stress
> less intermixing of scavenging air with the exhaust gas
> Exhaust valve can be made to open late