Shortround6
Major General
So those 4360's where drinking what? 150 gallons each per hour if that? And the jets about a gallon per minute per engine that is 3600 per hour each. Maybe they weren't drinking quite that much and maybe more like 1800 per engine per hour, that still makes that 1.5 extra hour nothing. The catch is with a recip that uses jet fuel and an efficient airframe that comes close to 737 speeds, why not? The recip will always be way better at fuel economy than a turbine.
According to one book the Boeing 377 could cruise at 315mph at 25,000ft using 467 gallons an hour. Max fuel was 7790 gals and range was aprox 4600 miles.
it carried 55-80 passengers.
An early 707 had a max fuel of 13,475 gallons and a max range (with allowances for climb and decent) of 4,650 miles max cruise at 25,000ft was 571 mph and econ cruise was 549mph height not given. 707s had widely varying passenger capacities depending on seat arrangements. but one typical arrangement was 36 first class and 95 coach class. Please note that this for the early 120 model with jet engines, when refitted with turbo fans (and the engines themselves could be converted) and a wing modification, the range jumped to 6,215 miles with the same fuel, cruise speeds went up just a bit.
707 could carry easily 50% (or higher) more passengers using 73% more fuel and make more trips per week (or even per day) and required less maintenance.
Please note that the JT8-D was coming into service in 1959-60 and modern turbo fans can do much better.
A modern diesel reciprocating engine might very well be able to equal the old R-4360 in power and fuel economy and even power to weight. But it is just not big enough to challenge the modern jets/turbofans and offers no economic advantage.