We already have a topic about this.

Historically, the T2 and T4 had a slightly smaller warhead (200 kg compared to the T1's 320 kg)

But: These torps were eletric. They had no wake. Plus the T2 had an induction fuze, IOW it's 200 kg warhead was far more deadly because it went off under the enemy's keel.

The T4 was indeed the first guided torpedo, it followed the enemy's engine noise. . .
http://www.navweaps.com/Weapons/WTGER_WWII.htm
That link has all relevant info.

But including this in the game would just make everyone cry becasue it would make the later German torps omfgz ub4r wtf

So I guess we'll be stuck with useless torps and useless sailor classes who would use the torps. Whatever.

Here's a better solution for the mismatching damage, lower the explosive power of the earlier torps. I'm fed up of splash damage from 2/3 german torps taking my 'health' down by half.

that becuz later as you get a bigger ship no longer would you be playing in rooms with torps say if you became a ca you would be plain cl ca or cl ca bb games and if you are a bb then you would also be playin the no torp type games, even in all games you wont be needing torps, atleast if you know how to play becuz everyone knows not to rush with a big slow ship... you stay back and snipe everyone