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You seem to be mostly hung up on fuel metering issues
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Viper, direct injection is a fuel metering system. Supercharging is an intake system and
does not have a thing to do with fuel metering.
It is two completely separate things you want to combine.
You point to the thermal benefits of introducing the fuel ahead of the supercharger instead of downstream of it. I agree it is there when compared to introducing fuel downstream of the supercharger in your INTAKE SYSTEM.
Got it but that does not make it more thermally more efficient that directly injecting the fuel in the combustion chamber. You are not looking at the heat capacity but are stuck on upstream vs downstream fuel introduction for your intake.
As Rolls Royce points out, direct injection is much more efficient than metering your fuel downstream or anywhere in the intake system.
Just because that small part of the intake system becomes more efficient vs introducing fuel downstream does not make the whole system more efficient.
A simple illustration of that basic principle.
1006 J/kgC – Specific Heat Capacity of Normal Air
460 J/kgC – Specific Heat Capacity of Steel
2100 J/kgC – Specific Heat Capacity of Gasoline
To change the temperature of a mass of 1 Kg of each by 2 degrees….
Air = 1006 J/kgC * 1kg* 2 C = 2012J
Fuel = 2100J/kgC*1kg*2 C = 4200J
Steel = 460J/kgC * 1kg * 2 C = 920J
Our 4200J of fuel energy goes to cool the 15C air…
4200J * 1kg /1006J/kgC = Change in T = 4.17 C
15C - 4.17C = 10.83C
Why do you think direct injection is the ultimate fuel metering technology and so desirable to have in an engine? If was not for the complexity and expense, all engines would be direct injected because it is the most efficient system mankind knows of at the present for metering fuel.
Rolls Royce also shows in the article you posted their system is not as efficient as directly injecting fuel into the combustion chamber combined with your supercharged intake.
Why? YOU STILL MUST HAVE A FUEL METERING SYSTEM ON YOUR ENGINE. Introducing the fuel ahead of the supercharger does not eliminate the basic problem of NON DIRECT INJECTED FUEL METERING SYSTEM, uneven fuel mixtures found by introducing fuel ANYWHERE in the intake system.
The only way to eliminate that is too directly inject fuel into the combustion chamber.
Direct injection engines with a supercharger STILL benefit from that supercharger intake system.