In the search for more engine power.
Posted: Mon Mar 13, 2023 10:00 am
In times of banks that go down the drain, it may be nicer to talk about the development of the internal combustion engine towards ever higher power outputs.
The 928 engine has two 37mm intake valves per cylinder. Is the increased flow with 2x42mm valves enough for a power output of 100 hp per cylinder? Probably not but 90 hp, should be within reach.
This led me to investigate how a Ducati 1285cc V-twin is putting out 210 hp from the factory, the racing version probably more.
The first thing that struck me was the unusually large cylinder diameter of 116mm and the short stroke of 60.8mm. A typical racing design for a high-revving engine, similar to a Formula 1 engine.
The second thing that struck me are the unusually large tianium valves, two intake 48mm valves, and two exhaust 39.3mm valves per cylinder.
Valve control is desmodromic, which means the possibility of very fast opening and closing of the valves, something that with a conventional valve control system would require very high spring pressure.
It can be assumed that the maximum valve lift exceed 14mm and that the intake ports, which are elliptical in shape, have an area corresponding to a round port of more than 55mm.
According to Greg Brown, this is a very huge port, too big to work.
Well, the Ducati engine is putting out 105 hp per tiny 643cc cylinder at 11000 rpm. Total engine power 210 hp. The engine has a maximum torque of 142Nm at 9000 rpm. Compression ratio is 13:1.
It also tells us that the 928 engine is fitted with relatively small valves and ports, much can be gained with extensive modifications here.
Åke
The 928 engine has two 37mm intake valves per cylinder. Is the increased flow with 2x42mm valves enough for a power output of 100 hp per cylinder? Probably not but 90 hp, should be within reach.
This led me to investigate how a Ducati 1285cc V-twin is putting out 210 hp from the factory, the racing version probably more.
The first thing that struck me was the unusually large cylinder diameter of 116mm and the short stroke of 60.8mm. A typical racing design for a high-revving engine, similar to a Formula 1 engine.
The second thing that struck me are the unusually large tianium valves, two intake 48mm valves, and two exhaust 39.3mm valves per cylinder.
Valve control is desmodromic, which means the possibility of very fast opening and closing of the valves, something that with a conventional valve control system would require very high spring pressure.
It can be assumed that the maximum valve lift exceed 14mm and that the intake ports, which are elliptical in shape, have an area corresponding to a round port of more than 55mm.
According to Greg Brown, this is a very huge port, too big to work.
Well, the Ducati engine is putting out 105 hp per tiny 643cc cylinder at 11000 rpm. Total engine power 210 hp. The engine has a maximum torque of 142Nm at 9000 rpm. Compression ratio is 13:1.
It also tells us that the 928 engine is fitted with relatively small valves and ports, much can be gained with extensive modifications here.
Åke