Just had a quick question. Im taking some 15's I had in a previous build and putting them into a different car (2008 pontiac Grand prix) I am building a slot ported box for 2 skar audio evl 15's with the SPEAKERS AND SLOT FACING FRONT ( current box dimensions are( 35" W x 15.5" H x 34" D)with 3/4 MDF @ 8.82 cubes gross. I made about 10 card board box mock ups to test fit a box in the trunk which has a terrible shape... so the box dimensions are restricted to what will actually fit in the trunk. My current design is going to have latches (2 on each side and 2 on top) to take the back of the box off for both installation and optional trunk storage as I also do a lot of camping. My question is Port Dimensions. I have come up with a port of 4'W x 14"H x 12"D. I wanted to tune close to 30 hz- I have used multiple port calculators -Slot Port Width is restricted to only 4 inches due to box width and port Height is max at 14 inches. The Skar EVL 15 has an xmas of 23.5mm. Almost every calculator says a port length of 12-13 inches. Does this sound ok? it sounds short but all the reading I have done states usually the length is calculated on box depth and xmas. I wanted to get some opinions before I build the port. I though of doing to round ports but my thought is a slot port in the center will also act as bracing for the box and keep it simple and functional. The calculators say the same depth for 2 six inch round ports anyway so it would be about the same. I know that the round ports will reduce noise but bracing for the ports would probably take up more internal box volume than the slot port design.

 

Update on progress

 

 

 

So far the port design sounds great FYI. The roof has a dent so most of the noise I hear is that dent wobbling along with various headliner rattles. The box design is working well. I am now tearing it down to fiber glass resin the interior and bed liner the exterior of the box.

 

 

https://photos.app.goo.gl/TCZYwqxW9H6eCF9U7