need help with port!

[mike82olds]

hello all! im a new user to the sight. i was running two 12" mmats procast on an older orion hcca 275g4. it was fun. but i wanted to get crazy so i got an fi btl 18 all options. its not here yet but it will be soon. i seenalot of boxes areound 8cf. my questions are what is gaind with the larger box? and what size and length should my port be to get about 32hz? i listen to rap, bass tracks and rock music. the sub will be getting around 4000watts. any help guys would be great! oh the instal will be in a 2002 alero. should be near comlete by dec this year unless i decide to run another sub. thanks again guys. oh i used the online port calcs and got different answers from each of them.

[Decaf]

for ~4000w u should be doing more like 6cuft or smaller after all displacement... thats double rated rms

btls are fine with 14-16sqin of port per cubic foot of volume

online calcs are off because they dont always account for sub displacement and people dont account for bracing, lots of other reasons they can be off

how are u going to fit an 18 in a alero? thats a big box... ur likely gonna have to build it inside the car

[Nirvalica]

This might be a dumb question, and sorry for hijacking, but how do you find the port area? Is it length x width x height? I dunno, I'm confused.

[tehbert0]

just width x height of the port. if your port is 15 in high and 3 in wide thats 45 inches of port

op, is the box going into the trunk of your alero?

[Nirvalica]

Thanks tehbert