A lot of times the type of equipment used was not due to a "
lack of technology" but due to manufacturing requirements, or service requirements or supplies of raw materials.
Not all crude oil contains the same amounts of different compounds/products. Some crude oil will yield much more diesel than another crude oil per barrel. You cannot always state that you can get X amount of diesel out of a barrel or crude. Sometimes setting up the refining process to make diesel means less gasoline per barrel or trades of other desired product.
Germans certainly knew how to make diesel engines of assorted types/sizes. The fact that they didn't use them in tanks doesn't mean they didn't know how to make one. It meant they had made other choices at the time.
The US for example, made thousands of Diesel powered tanks in WW II, The US army used hardly any. THe US Marines used diesel powered tanks because the navy had large supplies of diesel fuel for landing craft and other small ships. Diesels were usually both heavy and large for the power they produced. Often Armies wanted tanks of certain sizes/weights to fit existing bridging equipment or transport/recovery equipment. A bulky engine is worse than a small heavy engine as it requires a larger engine compartment the weight of armor for the larger compartment can be considerable if any but the thinnest armor is used.
Sometimes tech is actually the ability to manufacture stuff that works. The US supplied thousands of miles of Field phone wire to the Russians in WW II. It was of critical importance for two reasons. 1, was the general lack of radios in the Soviet army. 2, was the fact the Soviet made field phone wire had insulation that wasn't very good, it shorted out when wet. Insulation of phone wire isn't high tech/glamorus stuff but reliable communications was often critical.
Japanese radios may not have been as bad as some people claim. Part of the problems was the insulation/shielding on ignition systems of the engine. Some of us are old enough to remember AM radios in cars and the need to use certain types of ignition harness in the 50s and 60s.
see,
Identifying and suppressing radio interference
Best radio in the world is useless if mounted in a plane that is acting like it's own jamming station.
Torpedoes using oxygen instead of compressed air was not a new idea. Getting them to work wasn't even that new. The standards of manufacture and maintenance had to be very high however. A leaking oxygen container could cause real problems in an environment with flammable liquids and other combustible materials. The need for an oxygen generator/plant to top off the torpedoes on long cruises was also seen as a detriment and another source of leaks.
BTW the British did use torpedoes using oxygen enrichment on many of their cruisers I believe? somewhat better performance with less risk. But still replaced by natural air early in the war. Range dropped from 16,000yds at 33 kts to 5700yds at 35 kts. Later torpedoes used natural air but had higher pressure air vessels for increased performance.
Germans during the 30s had tried
high pressure oxygen (rejected due to explosion hazard on starting)
Hydrogen and oxygen
Liquid ammonia
fuel, oxygen and CO2 (given up due to fears of the CO2 leaking into the crew compartments on subs)
Magnesium or aluminum as fuel with oxygen (impossible to control)
Hydrogen peroxide.
German subs already had problem with stowing reload torpedoes. Using larger torpedoes might well mean a larger sub. Large subs dive slower and are easier to see on the surface, they need more room to turn and also present handling problems. Depending on orientation to the sonar unit they may be detected at longer range?
Perhaps some exchanges of ideas would have been beneficial, but often countries used equipment for what they thought was good reason, not because it hadn't been thought of yet in that country.