The Long Lance, carried on surface ships only, was the Japanese Type 93 torpedo. It got its range of 20,000 meters from using pure oxygen, not air for the combustion. Air is 78% nitrogen, which reduces the amount of oxygen available for propulsion and leaves a trail of bubbles behind the torpedo.
However the torpedo used on Japanese submarines was the Type 95, the Long Lance's little brother. It only sported a range of 9000 meters at 49 knots, 12,000 yards at 45 knots.
Our Mark 14 had a top speed of 46 knots and range of 4500 yards or 9000 yards at 31 knots. Explosive power of American and Japanese submarine torpedoes was similar. American torpedoes had a lesser weight of a superior explosive.
Now, what does that all mean? At a range of 9000 meters, the Japanese Sub torpedo (Type 95) could wander plus or minus 170 meters or 557 feet, for a total error envelope of over 1000' at that range. That means the torpedo probably would miss any single ship it was fired at, even with a perfect setup, which is impossible at that range unless you have radar.
So basically, what you're looking at is awesome numbers that meant nothing at all: no advantage whatever for the Japanese torpedoes used on their subs vs ours. Sure they had 3 knots more speed and a lot more range but a submarine couldn't carry enough torpedoes to make such foolishness as shooting from 9000 yards, and the expected wandering of the torpedo from the intended track made that doubly a foolish tactic.
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