You shouldn't use combustion engines. Use the dynamos of thermal expansion. They are much more efficient. But they produce Redstone Flux (RF), not Minecraft Jouls (MJ). So, you have to connect them with a conduit, to convert the energy (1MJ = 10 RF). I have made some power calculations on reddit: http://www.reddit.com/r/tekkit/comments/2qor4n/tekkit_main_question_best_way_to_transport_energy/cnakd11