45's in the corners, how many?

[Gunlex 10+ year member]

my design is like this

http://i33.photobucket.com/albums/d55/ratherbriding99/upload-1.jpg

I'm going to put a 45 in the port corner, but should i put them in the other corners too? Does this help anything?

Click to read more...

 

[Twistid 5,000+ posts]

your mom

 

[twisztdauthorit 10+ year member]

yes it helps make the box more ridged and stronger... if ur short on space then u dont need it but it never hurts.

 

[InhumanAcura 5,000+ posts]

yes it helps make the box more ridged and stronger... if ur short on space then u dont need it but it never hurts.

i guess it might add some rigidity..i always put them in to avoid dead spots that the 90 degree angle creates..think about it, do you think air will flow better with a bunch of sharp corners or with some nicely somewhat rounded edges..it just promotes better air-flow..

 

[iamamp3pimp 5,000+ posts]

you wont notice a difference unless you are metering, and even then, it might hurt you.

 

[Gunlex 10+ year member]

well, just 1 in the port corner it is then =D

 

[Lakota 5,000+ posts]

you wont notice a difference unless you are metering, and even then, it might hurt you.

x2

 

[iagrdshaka 5,000+ posts]

pour resin in the corners

 

[dleccord 5,000+ posts]

form tubes are better.

 

[yama168 10+ year member]

you wont notice a difference unless you are metering, and even then, it might hurt you.

Just curious how would it hurt the metering?. Ive always heard that the 45's help.

Aloha

 

[dleccord 5,000+ posts]

you wont even know the difference. its mainly for looks. but meterings are a different story.

 

[mlstrass 5,000+ posts]

Until someone builds identical boxes tested under identical conditions: one with no 45's, one with MDF 45's, one with resin, etc... then it's all speculation as to how it would meter. I've never read any test results like that. If anyone has them please post up for all to learn.

Until I read othewise I'll continue to use them as knowing how air normally flows a 45 will keep up the air speed/not restrict flow better than a 90.

I've ported/flow benched plenty of cylinder heads in my time and it's the same principle...

 

[Lakota 5,000+ posts]

Just curious how would it hurt the metering?. Ive always heard that the 45's help.
Aloha

One reason is because of the change of volume.

 

[Mr Cabinetry 10+ year member]

Until someone builds identical boxes tested under identical conditions: one with no 45's, one with MDF 45's, one with resin, etc... then it's all speculation as to how it would meter. I've never read any test results like that. If anyone has them please post up for all to learn.
Until I read othewise I'll continue to use them as knowing how air normally flows a 45 will keep up the air speed/not restrict flow better than a 90.

I've ported/flow benched plenty of cylinder heads in my time and it's the same principle...

Well, there is plenty of theory and speculation that has been circulated as to ports with 90 degree corners create more turbulence, thereby reducing airflow.

This myth has been around so long that no one has had the stones to step up and say otherwise and with the science to back it.

If anyone on here watches " myth busters " they did a show to prove or disprove the "myth" that a open bed pickup gets better gas mileage with the tailgate down than with the tailgate up.

Anyways, in the course of exercise was discovered that a pickup gets better gas mileage due to what is called a " Trapped Vortex " where by air flow becomes trapped in the closed bed of the truck and in effect this creates a " bubble " to which the air now flows over this " Trapped Vortex or Air Bubble " thus eliminates the air drag.

The same applied air flow dynamics occur in 90 degree corners of a slot port and there's more than enough proof on the internet to confirm this fact.

Also, here's another tidbit to munch on, the dynamic air flow principals are not the same for a ported sub box as those of say HVAC system because in a sub box air in not circulated in the same manner in a closed loop system, because a subwoofer only pushing/pulling air static air by the amount of the subwoofers xmax.

It only feels like the air blowing but in fact the air is only moving are such a high accelerated rate given at which the frequency the subwoofer moves.

 

[W8 a minute 10+ year member]

Thank you, Mr Cabinetry.

I've been watching these box building threads and trying to figure out why everyone is treating a ported box like an F1 cylinder head. There is no "flow" or constant rush of air in one direction. The air inside the port resonates back and forth. In fact, if you fill a port with smoke 98% of the smoke will stay in the port until it dissipates.