The advantage of the “split” turbocharger in Formula 1 engines

The 2014 Formula 1 season was characterized by the return of supercharging through turbocharger in a complex hybrid propulsion system. The new direct-injection turbocompound engines V6 of 1600cc have innovative systems for the recovery of the energy otherwise wasted (Energy Recovery System - ERS). The following article introduces a one-dimensional simulation of two different engine concepts. The first one is the “split turbocharger” arrangement that allows the design of a very short “log” exhaust; the other with a traditional short-shaft turbocharger that needs a more complex and longer “tubular” exhaust. The paper demonstrates that the longer “tubular” exhaust dissipates more energy that the shorter “log” one. In this way, the efficiency is impaired and the “log” exhaust makes it possible to have more energy available to the wheels with the same amount of fuel and with the same limitation on the fuel flow. Therefore, with the current limitations in the fuel, the “log” exhaust / split-turbo arrangement is more convenient for current Formula 1 engines. In this paper, loads, pressures, power and speed of the various components of the turbocompound engine were simulated. A standard turbocharger compressor and turbine were used for the log and tubular exhaust arrangement and the results were compared. Even if the turbocharger matching is not optimal, in fact the boost pressure does not reach the maximum allowed, the comparison between the two arrangements is still valid.