How Many Sq. inches of port for 2 Team RF 18's with 10,000 rms?

[Corey Draves]

View attachment 26528310Me and my buddy just built a in his trail Blazer from the C-piller back, It was 15 cubes and had 2- 18" Team Rockford Fosgates with a RD 7500.1 with a 16v system running at .7 ohm soo pushin close to 10,000rms, the wall we built had a 32x6 inch port but what we got to found out was that the box made the subs make a weird noise on certain songs and would keep making it the whole time the song was playing, sometimes so bad you couldnt even play certain songs... The noise was like the sub was bottoming out but we know that, that is impossible the way the coil is mounted. We thought it might be tuned to high so we built a port extension to see if that would make it better but tuning it to 32 hz from the original 38 hz made the noise way worse.. Leading us to belive there might be to much back pressure in the box so not enough port Sq inchs.. Ive read you wanna keep the port inchs a little lower then the Sq. inches of your subs? Is that true? Cause we got about 450 Sq. inches of sub and only 196 of vent... any help from experienced Wall builders would be appreciated...The pic is of it before the rest was walled and carpeted

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[wenn_du_weinst 10+ year member]

chamber is to big. I'd try 10ft and 180'' of port.