do you think you can fit 2 sa 8s in 1.86 cubes for box. If so it will prob be with an aero port can you have then do like a 45 or 90 degree bend since it is in a 86 firebird not alot of room to work with.
Yes, you will be ok with 1.86 cu ft heck just have half the aero port in box half out to give for the back hatch. It really depends what you are going for? SQ/SPL both. You have an advantage with the hatch..
Here is what I built in my old firebird intended for looks at the time. Two 12's in a sealed box at .8 cu ft per chamber with ~600 Wrms. The SQ was great! Even hit a 138.8 db at 44 Hz.. You can be surprised, especially with aero ports.
8.65 in length. By the way for these I didn't calculate considering any displacement of the ports so don't have it inside the box halfway or what not just flush with the internal side of the MDF sticking out.. Make sense?