View Full Version : Port Question

01-06-2005, 06:00 PM
Ok im Fiberglassing my Tire well and putting a brahma 15 in there. I fiqure it would be much easier to put a circle port in it. I went to do a port Calculator and it said 3 inch diameter and it only has to be 3.14 inchs long....... does that sound right? it seems short i wanted to tune it to 28Hz Seems alittle short to me.

01-06-2005, 06:08 PM
i had a similiar experience when i built my
round ported box...

everyone says you need ten billion square
inches of port and this and that...

i have a 3" diameter port thats 6.26" long
is tuned to ~32hz and i get no port noise...

i would say your port is right on...

now if you WANTED to have a gigantic
port you could go with dual ports or
quad ports or a larger diameter would
make it so you needed more length...

but for a spare tire well fiberglass job
i dont suppose you want to have to deal
with all that...

i would say go with it...

01-06-2005, 06:28 PM
Use a bigger port, 5.51" perphas.... With a 3" port you will experince nasty port noise, somebody correct me if Im wrong...

01-06-2005, 07:21 PM
one 3'' port seems a little small especially for a brahma 15.

only about 6-7 sq.in. of port area

01-06-2005, 07:30 PM
alright i have this port calculator http://www.carstereo.com/help/Articles.cfm?id=31 and i wanted to know if this is actually good to go by. Im not actually postive how big my Wheel well is but i would say between 2-3 Cuft Over the weekend im gonna Fill it up with packing penuts and see how that goes. But What is the problem with Round ports ive heard alot about port noise. Would it help if i get those Flared ports. Or what should i do.

01-07-2005, 01:53 PM

01-07-2005, 02:44 PM
flare on the inside would help. if you can, find some 6" pvc pipe. that would help. make sure you sand down all the edges after you cut it.

you can always mount the port like the baffle, and stretch the fleece over it if its too long. thats what id do. it would look cool too.

01-07-2005, 02:49 PM
According to this site you need 10 inches of port diameter if it were PVC or 80 square inches for a slot ie: 4 by 20 slot. With a 15 I'd use no less than dual 4 but you can try more or less.

01-07-2005, 02:53 PM
depending on the power that is going to it, and if his trunk is sealed or whatnot, should depend on port velocity.

personally, id go with around half the Sd (cone area) of the driver. maybe a little less. but then again, the box would increase in size. but thats the beauty in fiberglass. you can make it as big as you want :)