In The past Busses had the exhaust like a car @ bumper level , accelerating from a stop, too much oil injected,
Result, Unburned diesel Carbon soot in your face..
newer busses redesigned the piping to come out above the top of the bus..
Detroit Diesel Engines are 2 stroke , to achieve the high ignition pressures
they used mechanical superchargers to push in a lot of air..
Drag racing used those compressors with Petrol & Methanol fuels in 4 stroke engines..
/..
Last edited by fietsbob; 04-01-19 at 03:42 PM.