As a test yesterday I carefully watched torpedoes and have a series of screen shots showing a torpedo launched from HMS Lizard. Doing a little research this is a torpedo with 515 lb of explosive. For comparison a British 15" APC shell has has 60.5 lb and a 15" CPC has 129.3 lb.
Actually, the 1916 version of the 21" Mk II torp only had a 400-pound charge. The 515-pound charge was the 1917-1918 version. The 1914-1915 version was smaller. Ranges and speeds also increased during the course of the war, too.
All these 21" torps were Mk IIs but had varying number of stars (*) after their name. Most of these dealt with very minor changes that had no effect on meaningful game performance. Thus, we instead named them Mk II (E), Mk II (M), and Mk II (L), for early, middle, and late. Most Brit ships in Jutland have the (M) version, but the commandeered/purchased ships being built for foriegn nations usually had the (E) version even in 1916.
In the third you see the torpedo approaching SMS Ostfriesland, then see the explosion start and peak. Even at the peak it is pretty small, only going part way up the superstructure.
What do you have for your smoke and wake setting in the main display options? I have mine maxed out and a 21" torp hit makes a big splash. Not as big as a heavy shell, but MUCH bigger than shown in your pics.
You also have to keep in mind that the weight of the charge is only part of the factor when considering power and splash effect. The type of explosive has to be considered. The US MK 14 not only had a heavier warhead but the explosive used was much more powerful. Pretty much all WW1 torpedos used TNT while most all torpedos of WW2 used Torpex. Torpex is 50% more powerful than TNT.
Quite a few WW1 torps still used wet gun cotton, not even TNT. Also, heavy shells made a lot of their splash simply due to their huge velocity when hitting the water. Their explosive effect was a minor component of the splash, comparitively.