This refers to the turbo compound engine(s) where the compressor side of the turbo was connected back to the crank putting energy directly back into the engine.What engine do you mean by that. I think the Wright company produced several engines.
From the Canadian Museum of Flight:
To build an R-3350 Turbo Compound engine, Wright took an improved post-war model engine and sandwiched three power recovery turbines (PRTs) spaced at 120º intervals around the rear of the engine. The addition of the three PRTs between the power and supercharger sections added only eleven extra inches overall length compared to a non-turbocompounded engine. Each PRT is driven the by the exhaust gases of three front- and three rear-row cylinders. The power is transferred to the engine crankshaft through a fluid coupling. Turbocompounding added about 550 horsepower at take-off power and 240 horsepower at cruise settings over a similar non-turbocompounded R-3350.