On the TV series, it was seen that this weapon had an exposive effect upon impact and could cause almost any ship to explode if one had a solid lock. Primary explosion was most likely the reactor or on-board fuel tanks being struck during the fight. Given that the gun ports on the Vipers were roughly 30mm, it is likely that the Laser-Torpedo were able to bring at least 1,000cm^3 to its boiling point. If the aforementioned mass was made of iron, with a boiling point of 3,000° C, each individual Laser Torpedo gun would have a power of 12.5 gigaawatts (12,489,028,920 watts), giving them a combined, low-end power output of approximately 25 gigajoules per volley.
Given that we are theorizing that armor in the Galactica universe is some 20X greater than iron, the main weapons on Vipers and Raiders would be rated at roughly 500 gigajoules, 250 gigawatts per gun-port. Some argue that these figures at too low, given the way Vipers and Raiders exploded, but does fit what was seen when Apollo's brother Zack was struck by Cylon fire. It is likely that the larger explossions were due to the fuel tanks being ruptured and not the weapons.