Experiments in supercharging diesel engines from the 1930s onwards, initially by Sulzer[REF] and Saurer, had shown that a robustly constructed diesel engine could be supercharged heavily, such that its output torque could become several times greater.
By applying a turbocharger, it is possible to increase the torque (and thus power) at low speeds, so as to match the naturally-aspirated maximum power at the torque peak.