My idea, check it:

[ngsm13 5,000+ posts]

So you insult me, instead of listen.

n00bx.

nG

 

[SPLEclipse 10+ year member]

theres no point in having fans on the exhaust side, as you wont be moving any more air than with just the intake side. "push/pull" is only needed if you want to direct the airflow over a particular small space. you cant direct the airflow with all that duct work (wich i personally think is waaay to much). you need some velocity to actually remove the heat. if i were you, i would put a couple fans at the top of one side of the enclosure (the top is where the heat rises to), and an exhaust port on the other side. forget the pipes.

 

[James Bang 5,000+ posts]

So you insult me, instead of listen.
n00bx.

nG

softy.

 

[IDSkoT 5,000+ posts]

So you insult me, instead of listen.
n00bx.

nG

I thought you were just patronizing me just to do it.

But I'm listening.

theres no point in having fans on the exhaust side, as you wont be moving any more air than with just the intake side. "push/pull" is only needed if you want to direct the airflow over a particular small space. you cant direct the airflow with all that duct work (wich i personally think is waaay to much). you need some velocity to actually remove the heat. if i were you, i would put a couple fans at the top of one side of the enclosure (the top is where the heat rises to), and an exhaust port on the other side. forget the pipes.

Very good point. I may move the exhaust from the case to two points above each of the amps, and then have them all connect and exhaust together.

Expect a new draft soon.

 

[audioholic 5,000+ posts]

theres no point in having fans on the exhaust side, as you wont be moving any more air than with just the intake side. "push/pull" is only needed if you want to direct the airflow over a particular small space. you cant direct the airflow with all that duct work (wich i personally think is waaay to much). you need some velocity to actually remove the heat. if i were you, i would put a couple fans at the top of one side of the enclosure (the top is where the heat rises to), and an exhaust port on the other side. forget the pipes.

Exactly. Running fans in a push/pull combination is a surprisingly common mistake. Dont be common.

 

[IDSkoT 5,000+ posts]

Exactly. Running fans in a push/pull combination is a surprisingly common mistake. Dont be common.

Well, my fan knowledge stops at computer cases.

My case was reaching 55* C temperatures with 5 fans, all exhaust. I turned two around, 2 intake 3 exhaust, and now it rests at ~40 under loads. So, the push/pull method worked for that. I was just using the same application with this. I figured I'd try to make a sort of vacuum effect with it, with just a single volume of air.

 

[James Bang 5,000+ posts]

when going w/ the push/pull method or any method, imo, placement makes a big diff.

 

[audioholic 5,000+ posts]

Your computer case is not air tight. And many of the fans in the case, even the ones mounted directly to the case itself, are meant as direct cooling to critical components on the computer itself, not just as general through-put air movers.

A fan has a CFM rating, how much air it will pass through its blades in the duration of a minute. Mount this fan to a small box with a hole at the other end. The fan is moving that X number of CFM. Now add an identical pusher fan to the other hole. They both still move that same X number of CFM, therefore the same amount of air is being displaced within the box as would only one fan. No gain from adding the extra fan.

Think of it another way. Mouning two pusher fans (or two pullers) end to end with each other, and then turn them on. Do they spin twice as fast? They do not. So the same X CFM is still moving through each fan, no noticeable gain.

Running fans in a push/pull configuration will help the efficiency of each fan slightly. But this lower resistance will not equate to any significant increase in air movement through the blades. But, if you were to take both fans make the pushers (or pullers), each with their own corresponding holes, you WOULD double the amount of through-put air through the box/space.

 

[IDSkoT 5,000+ posts]

Your computer case is not air tight. And many of the fans in the case, even the ones mounted directly to the case itself, are meant as direct cooling to critical components on the computer itself, not just as general through-put air movers.
A fan has a CFM rating, how much air it will pass through its blades in the duration of a minute. Mount this fan to a small box with a hole at the other end. The fan is moving that X number of CFM. Now add an identical pusher fan to the other hole. They both still move that same X number of CFM, therefore the same amount of air is being displaced within the box as would only one fan. No gain from adding the extra fan.

Think of it another way. Mouning two pusher fans (or two pullers) end to end with each other, and then turn them on. Do they spin twice as fast? They do not. So the same X CFM is still moving through each fan, no noticeable gain.

Running fans in a push/pull configuration will help the efficiency of each fan slightly. But this lower resistance will not equate to any significant increase in air movement through the blades. But, if you were to take both fans make the pushers (or pullers), each with their own corresponding holes, you WOULD double the amount of through-put air through the box/space.

It makes sense.

So, if I'm set on 4 fans, have 4 exhaust holes roughly the same diameter as each fan?

 

[audioholic 5,000+ posts]

It makes sense.
So, if I'm set on 4 fans, have 4 exhaust holes roughly the same diameter as each fan?

Correct.

 

[IDSkoT 5,000+ posts]

Correct.

So, if I made all 4 of those fans into push fans, and then put 2 holes, the diameter of the fan x 2, that would be the most efficient, correct?

Also, should I funnel it? (The fans are 3.14" [90mm], so I was gunna use a 3" PVC pipe. Should I use a 6" PVC instead?

I'm sure there's math behind it, but I don't know any of the calculations.

 

[audioholic 5,000+ posts]

So, if I made all 4 of those fans into push fans, and then put 2 holes, the diameter of the fan x 2, that would be the most efficient, correct?
Also, should I funnel it? (The fans are 3.14" [90mm], so I was gunna use a 3" PVC pipe. Should I use a 6" PVC instead?

I'm sure there's math behind it, but I don't know any of the calculations.

Im not sure what you mean by 'the diameter of the fan x 2'... just think of it like port area. The corresponding holes for the inlet air have to match the circular area of the fans. You can do this by having 4 holes the same size as each fan, or one large hole that is equivalent to the same area as the 4 smaller holes. Im sure you get the idea. The only thing I would add to the hole placement discussion is, where you place the holes can be important. If you have 4 components in your space you wish to cool, it may be more beneficial to have the 4 separate intake holes, near each component, to allow air to be swept directly across each piece. As someone mentioned earlier, cooling is most efficient with higher velocity air moving across the cooling fins. If cooling is critical to a certain piece, make sure it gets direct airflow.
Funneling only tends to alter air velocity. If you are worried about efficiency, do as suggested above and look into keeping your ducting as short as possible. Ideally there would be no ducting. Im not totally sure I follow your master plan on sealing off your trunk.... but that's a large enough space that even being sealed off you should be able to vent your amplifier heat directly into it, rather than trying to pipe it into the passenger compartment... if Im understanding your plan correctly.