i've been reading about amp installation and so far all the articles say don't mount it upside down because it won't be ablwe to get rid of the heat, my problem is i only want to get an amp if i can mount it under the rear deck, i don't want it getting in the way of anything, are there any amps that can be mounted upside down or that don't get as warm as others, and isn't the mp3's amp mounted in the same way?

 

truely depends on the the amp I suppose. Some are designed so that yes, you would be cooking the board. But others use large heat sinks, or better yet forced induction via fans. (I still like old McIntosh and Adcom amps for this very reason, and they are built like killers!) The other way to get what you want, would be to build a U shaped shelf, mount the amp to the bottom of the U, right side up, and then attach the upper ends to the deck so the amp is suspended on the shelf. I ultimalty did this in my old protege sedan, and am considering doing the same in my Mazdaspeed with the EQ/processor. The small shelf method still leaves lots of room...
I had an amp mounted upside down in my LX by the way to start with, and it did just fine, I changed it to satisfy myself about the detials of the install. I always felt I had been a touch lazy be just tapping it into the deck upside down!

Good luck, and let us know what direction you decide to install!!

 

I have mounted amps upside down too without any dire consequences. If you plan on doing something like this, consider how hard you will be pushing the amp, and what sort of air circulation you will get. For example, I wouldn't be too keen on an upside down mounted amp if I was running it at low impedances with a sub. :disclaimer: Also, if you wish to do this, I would question the availability of warranty if you do encounter heat problems :end disclaimer:

Note that the tray idea Dave suggests would also be good for an under the seat type of mounting job for the P5ers out there trying to save on space but not cut the floor vent and put it right on the floor. I have my amp mounted upside down attached to my seat in my P5 currently, and did a tray deal with my wife's old Sidekick to keep the amp right side attached to the seat. The only thing with this is you have to be careful running wires to prevent binding and such when the seat is moved. I also did an upside down amp mounting with an old alphasonik amp (30W per channel - woohoo!!), that I ran full tilt every day for probably 2 years with no ill effects (I am still using that amp in another install and I have had it now for probably 8 years).

The tray suggestion is a very good idea if you want to follow all the rules and still have an out of the way installation. It also can be used to create a neat and fairly secure place to mount components.

 

i wouldn't be running the amp too hard, i won't have a sub, just 4 speakers, plus it takes me like 5 minutes to drive to work so if i did run it hard it wouldn't be long periods of time

 

sounds like with your application, you could get away with mounting it upside down. But then when you have to take a road-trip on a hot day and your amp keeps going into thermal protection mode, you'll be sorry (road trips suck without tunes!). I would say the same thing: build a little shelf or bracket under the rear deck, or between the shock towers. When auto manufacturers put amps here, they design them for the heat to disipate from the bottom (the part against the rear deck) and put a little airspace in there for cooling. Or, they use the shelf design and put a small plastic shroud over everything so you don't see it.

 

the perfect thing to build that bracket out of is using a pair of hand brakes and HVAC slip... make two full mounts and leave about 2 or 3 inches of clearance above the amp for ventilation... these can be sunken in with zap screws or any self-tapping metal screws. you can also use angle braket/angle iron, metal strapping or custom bent L-mount shelving brackets. and as far as your amp running in to protect mode, being that it's not going to be mounted on the back of the seat, i would be careful, as the temperature of your trunk can reach well near or over 140 degrees farenheit in 80 degree weather, or direct sunlight in such temperatures. but thats a risk for any amp in summer heat, hell, mine overheat easy as ****, thats why it helps to mount them on the 40 section of the 60/40 seat and keep the a/c on or the window down . also, make sure that when you close and open your trunk that your trunk torsion bar (i think thats what it's called) isn't hampered in operating in any way... kinda helps your trunk to spring open when you hit the release... as well as keep it open when the wind blows good luck

edit: that hvac slip material found at home depot most likely will be extremely sturdy...cutting that **** takes finess and strength