5
CALCULATING ENCLOSURES
It is difficult to give exact box dimensions that are universal for all cars and trucks. It is for this
reason that you must be able to calculate the space in which you have available in order to achieve
the proper air volume required.
It is recommended to build your enclosure from 3/ 4” thick MDF (medium density fiberboard).
Make sure the enclosure is sealed airtight.
Calculating External Volume
To calculate box volume, measure the outside Width x Height x Depth of
the enclosure.
Example 12” x 14” x 9”=1512 ÷ 1728” Cubic feet
Next you must convert cubic inches into cubic feet. To do this, you must
divide the cubic inches total by 1728”.
Example 1512 ÷ 1828=.875 Cubic feet
Calculating Internal Volume
To calculate the internal (net) volume of the above box you must first multiply
the thickness of the wood you are using by Two(2).
Example 3/4” x 2= 1.5“
Next subtract 1.5 from each of the outside measurements of the box.
Width
Height
Depth
12 - 1.5 = 10.5 14 - 1.5 = 12.5 9 - 1.5 = 7.5
Multiple the new totals
(H x W x D)
Example: 10.5 x 12.5 x 7.5 = .5696
Next you must convert cubic inches into cubic feet. To do this, you must
divide the cubic inch total by 1728”.
Example 984.375 ÷ 1728=.5696
cubic feet.
