saviour stivala wrote: ↑Sun Jun 30, 2019 5:38 pm

10500 rpm is the maximum power speed of the present power unit, above 10500 rpm it is not possible to produce any more power. If it wasn't for the maximum fuel flow rate rule set at maximum of 10500 rpm these power units would have been designed to run and produce their maximum power output at a lower maximum rpm. and they would have achieved a much better efficiency percentage number.

where would this 'much better efficiency percentage number' come from ?

imagine we redesign to halve the rpm .....

this would need double the induction pressure ('boost') to double the mep

doubling the mep would double the frictional loads on the power stroke - so frictional power there wouldn't fall

piston compression work (already very high) would be more than doubled - so frictional power there would rise

doubled mep would also need bigger bearings and crankshaft - so more frictional load there (ok not more power)

compressor power would more than double - and compressor efficiency would plummet (unless it became 2 stage)

ie there is no increase in recovery from raising boost - and recovery will fall where compressor efficiency falls

and this all assumes that detonation can be managed without efficiency loss - despite the doubled mep

the engine rules weren't written by fools