An earlier question concerning lower high altitude cruising fuel efficiency of the B-29 bombers with 4 x Wright R-3350 air-cooled radial Cyclone engines made me wonder about the Lancaster bomber, which was powered by 4 x Rolls-Royce Merlin liquid cooled in-line engines.
The R3350 needed to enrich its fuel mixture and open its draggy engine cowlings to avoid overheating its engines, negating the benefits of higher TAS with greater altitude.
Was the Lancaster able to avoid these issues with liquid cooling and gain fuel efficiency at higher altitudes, or would the extra demands of turbo and or supercharging limit these gains as well?
What was the Lancaster's best cruising altitude?