Port bracing question

[Grinder]

Will pvc elbows from say Home Depot match up with the Precision Port kits?

Not likely ...but even if they did, they are of entirely different material thickness (i.e. not at all conducive to smooth airflow).

[Queef]

You can buy a "street ell" ( one male and one female end )to go inside a regular 90 with two female ends. 90+90=180

The 6" pvc will cost substantially less at Home Depot , than a PR .
Using flares from PE with pvc , do it , you can get it to work !
Glue & Primer work best with pvc and DWV or drain/waste/vent pipe is thick/heavy pipe.

[Surfer J]

How do passive radiators work? How do I go about installing and tuning one? What size do I need for my HST-15? Also where can I get one? Again thank you all for the help.

[Queef]

https://www.parts-express.com/dayton...IaAhoZEALw_wcB

It needs to be bigger than sub and may drop a half-octave. Tune to 30 hZ , 7 hZ lower to 23 hZ

[Grinder]

Here's a good place to start: https://earthquakesound.com/index.ph...s/car-passives

PRs mount pretty much like any other driver (though only vertical is recommended, due to weighted cone). Tuning is done by simply adding/removing weight from the passive cone.

[Queef]

Surfer J ,
I'd build a "slot-port" , because . . .
https://www.caraudiojunkies.com/cont...closure-design

A sealed box is 'very forgiving of errors' , not so for a ported-box ("exact is all You want").
Passive radiators - expensive , and size .

[Holmz]

Here's a good place to start: https://earthquakesound.com/index.ph...s/car-passives

PRs mount pretty much like any other driver (though only vertical is recommended, due to weighted cone). Tuning is done by simply adding/removing weight from the passive cone.

And then it is like changing ports until one gets it "just right".
With a slot or a tube, it is a bit harder to "unglue" a box, than to change a weight.

And some 'stupid low' tuning is a lot easier.

[Surfer J]

What is the minimum distance I need to have between the port opening and the rear wall of my truck for a 6” port?

[Queef]

Move it forward/backward and listen , otherwise , do like everyone else . . . Build it and put it where it fits ! Compromise .
Six inches is minimum.
Could port be located on (top/same side as sub/any side not facing a surface - wall, floor)

[Grinder]

What is the minimum distance I need to have between the port opening and the rear wall of my truck for a 6” port?

I'd say at least 6" to avoid turbulence/noise - and perhaps even farther, to avoid inadvertently lowering tuning (i.e. effectively lengthening port, due to its proximity to the rear wall of your truck).