The P-38 has a weird engine design

Video from the channel Real Engineering about Lockheed P-38 Lightning, linked on its Above Ten Thousand entry. Duration: 2:59. Language: English. Video type: Documentary.

Short piece on the supercharging system of the Lockheed P-38 Lightning. Its two Allison V-1710 engines, liquid-cooled V12s with a single-stage, single-speed mechanical supercharger, also received a turbocharger driven by exhaust gases, which fit behind the engine thanks to the space in the booms.

The video compares it with the British Merlins, which had a two-stage, two-speed supercharger, and with the P-40 Warhawk, which carried only the Allison's supercharger and performed poorly at altitude. It explains that the mechanical supercharger responds instantly while the turbo has lag, and that both heat the intake air.

To cool that air, Johnson integrated the intercooler into the wing's leading edge: a network of thin tubes cooled by air entering through a small inlet and exiting at the wingtip, with very little drag penalty.