Uh...246 and 368 knots...?
Whatever floats your boat, man, but those are LUDICROUSLY high speeds! Sure, there are many things you can mod in this game, but I'm pretty confident the game engine has its limitations. Try something more down to earth, like upping the speed by +10 knots, I'm sure you'll see it's working. It's still torpedoes you're trying to mod, not a space shuttle's launch speed!
ETA: oh, and welcome aboard!