*Sigh*
You're not going to even make near an M-80 if you stick together a few firecrackers. M-80s contain 3-5g of flash powder in them, each of your firecrackers contain 0.05g of flash powder in them. Do the maths.
Secondly, using lighter fluids or any other hydrocarbon based fuels with fireworks will never work, they often ruin the compositions. Also, do not use metals and pyrotechnics, so do not listen to the above advise and use copper pipes. M-80s use thick cardboard tubes, thick as in thick enough to stand on, you should not even attempt to make M-80s because they are incredibly powerful.
Result of an M-80:
