Help designing a dual 8” ported box for a BMW Z4 E85

Zedfour

CarAudio.com Newbie
Apr 5, 2019
3
0
Hi I’m New to the forum and I’m desperately trying to build an enclosure for 2 x powerbass xl-840d 8” subs. The problem is, I have a 2008 Z4 roadster...

I’ve custom fabricated the dash and installed a pioneer avh-8500bt double din, I made tweeter pods for the A pillars and have 3 way hertz energy/ audison prima mixed components front stage run off a Helix B4 blue 4 channel & alpine 6 x 9s custom built in the rear cubby holes run off the hu.

ive removed the rear shelf so the trunk isn’t sealed!

the subs are 200 rms each and I have a massive audio b2 nanobit to run them @1ohm 

is there anyone who can help me with what size enclosure I need? The max size I have is 32” width 12” high and 14” depth 

would they be better firing up, port back? This is the sub spec

19C23929-EF9A-4AFC-AD65-75C95F8EBB2E.jpeg

 
OP
Z

Zedfour

CarAudio.com Newbie
Apr 5, 2019
3
0
It’s a convertible, 32” width 12” height 14” depth is the largest dimensions I have to work inside 

 

THATpurpleKUSH

Smoke weed everyday
Sep 30, 2009
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Banging gears and passing queeers
EBP on those subs is about 80 which indicates that a ported box should be used. I don't like the fs being so high at 52hz, don't expect much below 40hz with those. 

I would go with about .6 to .75cf per sub and tune them around 40-42hz. 

 
OP
Z

Zedfour

CarAudio.com Newbie
Apr 5, 2019
3
0
EBP on those subs is about 80 which indicates that a ported box should be used. I don't like the fs being so high at 52hz, don't expect much below 40hz with those. 

I would go with about .6 to .75cf per sub and tune them around 40-42hz. 
Thanks, I’ll see what I can come up with. If it sounds like mud, what choice of sub for such a small space would you recommend?

 

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