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View Full Version : 32" of round port enough for 3.5 cf?



I Like Waffle
05-12-2010, 11:35 PM
Looking at building an enclosure for a single cheap 15" and im figuring a good size would be 32" of port via 2 4" abs tubes 15" long. Box is around 3.5 net. Whats everyone think? Ive used round ports a couple times and they worked great, but im wondering if like 10" of port per cube will be fine for round ports?

d-REW
05-12-2010, 11:41 PM
32"? two 4" aeros comes to 25.12" id do three 4"= 37.68

beany
05-12-2010, 11:52 PM
Curious, what equation does everyone seem to be using to find the volume of a circle port? Cause I seem to be doing it wrong.

Bumpin' Goalie
05-12-2010, 11:55 PM
Edit: (Mental lapse)

R^2 x Pi = Area

shizzzon
05-12-2010, 11:58 PM
lol, maybe for a 4" aero but that's the only size that would work for.

The proper formula for AREA, not Volume is Radius^2 x Pi(3.14)

Volume is- Radius^2 x Pi(3.14) x Length

mazdakid
05-12-2010, 11:58 PM
4" would be 2x2x3.14=12.56

Bumpin' Goalie
05-13-2010, 12:00 AM
lol, maybe for a 4" aero but that's the only size that would work for.

The proper formula for AREA, not Volume is Radius^2 x Pi(3.14)

Volume is- Radius^2 x Pi(3.14) x Length

Lulz good catch, lazy mental moment for me. Just did it in my head and had the 4" stuck where 2"x2" shoulda been. Gracias.

beany
05-13-2010, 12:01 AM
Hmm, I've always been taught the volume of a cylinder is πr^2h, So in this case his 4" tube would be V=3.14(2^2)14=175.9?

Why is this so incorrect?

Bumpin' Goalie
05-13-2010, 12:03 AM
When port area is discussed, the main factor is area of the opening. Too small=noise. Too big=a variety of issues.

When tuning is discussed, port length is then also included.

You need sufficient port AREA for a certain enclosure. Usually 12-16in per cube for slot port. Slightly less can be done for flared aeros.

Then once you have proper port area, you adjust the length to achieve the desired tuning.

beany
05-13-2010, 12:04 AM
lol, maybe for a 4" aero but that's the only size that would work for.

The proper formula for AREA, not Volume is Radius^2 x Pi(3.14)

Volume is- Radius^2 x Pi(3.14) x Length

Okay so isn't the volume of a cylinder and area the same thing?

Bumpin' Goalie
05-13-2010, 12:05 AM
Okay so isn't the volume of a cylinder and area the same thing?

Nope. Port Area is just the opening.

mazdakid
05-13-2010, 12:07 AM
no volume is how much the whole port takes up

beany
05-13-2010, 12:09 AM
Nope. Port Area is just the opening.

so when calculating the port area of circle ports is just that number before multiplying by the height to find volume, i.e. 6" circle = 9 x pi= aprox 28.26?

I Like Waffle
05-13-2010, 01:37 AM
2x2x3.14 x 15" for the ports gives me pretty much 32" of port area, which is about 10 per cube. Ive heard of people using less, these arent flared though i assume that makes a diff?

If i do one 6" port i can get almost 36" of port area, think i should go with one 6" instead?