When you state 'adjusting the torpedo speed' are you looking for a 'cheat' or simply how you do it in the game? If it's the in-game function you're looking for it's simply a switch on the PK instrument, click on the Torpedo Speed button (it has 3 settings but only 2 work, an oversight by the devs which has not been corrected).
Ref the radar; you can ONLY turn off the surface-search radar (simply deselect it on your 'menu' buttons at the bottom of your screen). You CANNOT switch off the air-search radar, it's automatic and has no display, simply a crew member telling you about air contacts.