Sub location

Look we are going to be building a box for a guy and he wants me to build the box for 4 Kicker CompVRs D2ohm and have them fireing to the cab of the car.  Now my idea is to build the box so it looks kind of like a C shape with one sub on the left and right side of the C shape and the other two in the middle of the C shape all facing towards the front of the cab.  He wants all the pressure to go into the cab of the car.  Now with the box completed we are going to build like a lid for the top of the box so when you open the trunk you will not see the speakers but a top like thing.  And the box will be having all subs ported and when you flip the back seats down the pressure from the subs will go into the cap.  I know this is a hard thing to understand with out seeing it but, we will have pics when completed.  The question is will the fireing of the subs get the pressure in the cab of the car like he wants it?

Thanks

This is my advice to you Walker.  You've let it be known that you're in business, not just enjoying a hobby.  So understanding how a vented speaker system actually works is necessary.  It doesn't come to you quick and easy but it will become clear after time and a lot of reading... and building vented enclosures.  Here are some help articles, calculators and programs that will start helping make your life and business more rewarding.  Save these to file for reference.  Download the WinISD and start getting used to it.

https://www.hometheaterhifi.com/volume_5_2/cmilleressayporting.html

https://www.carstereo.com/help2/Articles.cfm?id=31

https://www.mhsoft.nl/spk_calc.asp#top

https://editweb.iglou.com/eminence/eminence/pages/params02/params.htm

https://www.bcae1.com/

https://www.linearteam.dk/default.aspx?pageid=winisdpro

As far as your current question is concerned:  air pressure will fill an enclosed area.  The inside of the box gets pressurized when the cone moves inward, and  the air on the outside of the box gets pressurized when the cone moves outward.  That pressure creates the sound waves.  Air pressure will extend throughout an enclosed area, so if the trunk is enclosed, the trunk will become pressurized.  If the trunk has an air opening into the cab then the trunk and the cabin will become pressurized.  Facing the subs one way or the other has nothing to do with it.  IMO, the port opening on a sub box located in the trunk can open on any side of the box where it fits best.  The port opening should be flush with the box, not extended into the cabin.  That's not where the majority of the pressure is coming from....it's coming from the movement of the cone.  The two pressure sources -- the cone and the port -- should be located together in one common area, which in this case is the trunk....because the output of sound at the port needs to blend with the sound from the cone.

This blend of sound, coupled with the added cabin gain from the trunk cavity, now makes the trunk the "source" of the sub bass.  Aim the sub box for best sound quality while listening from the driver's seat, and create or allow an opening through the well-damped back parcel shelf for the air pressure to enter the cabin.  I used a factory speaker opening in my Taurus for this purpose:

Cool man thanks.  The car I am doing has a 60/40 split rear seat.  So we built a box for 3 12 memphis subs and air space was 6cu.ft so we have the subs in a wedge type box built with BassBox Pro and the port is on the top of the box.  Now in the rear of his deck there is a like 6x6 square opening with nothing there so I figured that would help with the pressure into the cabin and also with the seats flip down would help.

Thanks