Dr. Acula wrote: ↑
Fri Dec 13, 2019 2:05 pm
You have to look at the PU as one big package.....
.... if they improve combustion efficiency, it also means they lower the energy content of the exhaust gases and that can be a double edged sword. Because now they would have less energy available for the MGU-H. This would require a redesign of the turbine. If the new turbine has the highest efficiency at a different rpm than its predecessor it also means you would need a revised compressor to make up for this. So basically an improvement in combustion efficiency can also require a completly new turbocharger just as a side effect.....
improved combustion efficiency is not the correct descriptor for this scenario
improved thermal efficiency is the correct descriptor for this scenario
(importantly, posters often seem to make this misattribution)
thermal efficiency is the % of the heat liberated in-cylinder that is converted to work in-cylinder (maybe 60%)
combustion efficiency is the % of fuel supplied that is burnt in-cylinder (maybe 95%)
improved combustion efficiency increases heat liberated in-cylinder ....
but c. 30% of this increased heat goes to exhaust - so slightly raising (not lowering) the energy content of the exhaust
ok the F1 engine has 2 expansion stages (major and minor) and similarly 2 compression stages
ie (some of) the fuel unburned in-cylinder burns in the exhaust upstream of the turbine