Complex sentence: The cockpit was nevertheless warm and comfortable, in part because the radiator pipes ran alongside the cockpit walls from the fuselage-side mounted twin radiator blocks, usually featuring pilot-operable shutter doors directly forward of each radiator core to control engine temperature.
Split into simpler sentences: The cockpit was nevertheless warm and comfortable, in part because the radiator pipes ran alongside the cockpit walls from the two side-mounted radiator blocks. Pilot-operable shutter doors directly forward of each radiator core allowed control of engine temperature.