Turbo-compounding:
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You would gear the turbo directly to the crank as belts are subject to more friction/slippage. In our application, the flywheel is the most logical choice. The biggest issue is overcoming pulses in power, as they create speed differentials between the turbo and the crank. This problem is usually solved through a friction clutch or a torque converter. The development of this system would probably be expensive, require precise machining, and advanced engineering. It is definately doable, but not for the faint of heart.
The above picture shows a Scania Turbocompound engine. This application was developed by an English company named Holset, but has been around since at least WWII. The Allison V1740 (of P-40 Warhawk, P-38 Lightning fame) was tested with a turbocompound and the technology went commercial on the DC-7 with the Wright R-3350. Holset used a series turbocharger system, where the first drove a conventional supercharger and the second aided the crankshaft. Obviously, sizing would be key. I think Big Rigs in Europe reported a 5% increase in mileage, but the technology has be ousted due to heightened emissions standards.
- LostCause