ringo wrote: ...... 540 hp to the flywheel is my guess. MGUH is 200hp.
As to why manufacturers haven't been doing this, i really don't know. I believe back pressure is the issue. I will investigate if that amount of power can be taken off without some issues.
You can look on the total energy unit efficiency to get higher numbers, but the ICE efficiency is 31%.
540 crankshaft hp at 31% is very good if there's 200 hp electrically, both from the same fuel (except for the F1 rules)
IF that 200 hp has cost, say, 100 hp crankshaft power this does not matter in principle, there is a real gain in fuel efficiency
as long as we don't tell ourselves that we have gained 200 hp for free (if our real gain is 100 hp)
we don't know what crankshaft power the electric compounding has cost
the Allison T-C had a low CR and its best efficiency when its induction and exhaust pressures were equal (not so for best power)
but could not seperate crankshaft power from turbine-recovered power
the Wright T-C had its best efficiency when the induction pressure was about 0.15 bar relative at sea level
Wright proved the 'no back pressure' argument but kept quiet about the exhaust tuning gain at max power built in to the T-C
and metered in service the recovered power for operational purposes
one would imagine that high exhaust pressure tended to promote detonation (by raising pressure and temperature)
but high exhaust pressure was, even with CR suitably lowered to avoid detonation, the recipe for efficiency
so there was a potential conflict
but 2014 F1s idealised DI, managing combustion by managing injection rate after sparking, would eliminate this conflict
a year ago I suggested that exhaust pressure should be raised for better thermodynamic efficiency (than otherwise) over 10500 rpm
road car GDI can to an extent give to spark ign engines the advantages of diesel engines without the disadvantages
so is 2014 F1, in another way, with inherently more expense and complication
