Trunk cooling came up in another thread, and as I'm currently entrenched in a battle against rear-end heat, I thought I'd share some of my experiences with my NSX CarPC.
First, a little background. CarPC's are nifty tools that can update a 15-year old car (or even an 05) back to gaget levels you'd want in a modern car. While offering all the features you'd find on a fully equiped headunit, the CarPC allows total flexibility and upgradablility. This flexibility comes at a price, since standard headunits are simpler and have less things that can go wrong. Introducing a PC into your system introduces a lot of complexity. There are certainly benefits for a standard headunit over a pc, and vice versa - no need to figure out what is better, since it depends on the what the user wants.
In the nsx, there's only a few spots available for locating a PC, and your choices are restricted by the size of the PC you choose. There are several form-factor options, ranging from ones that are standard DIN sizes, to Mac-Minis, mini-ITX based systems, Shuttles, Mocha/Cappucino, etc. The first PC I installed into my NSX was a Mocha PC. It's about the size of a mac mini, but has a P4.
http://www.cappuccinopc.com/mochae5042b.asp
It's small enough that you can fit it in the glovebox! I was able to tuck the wires in various crevices in such a manner that I could hook it up without needing to cut any holes in anything. Amazingly, even during long trips (6-8 hrs), it never overheated, even though it was enclosed in the glovebox the entire trip. Unfortunately, it required a 20V power supply, which is somewhat annoying to provide. My solution was to use an inverter to power a 120vac->20vdc adaptor from an old dell laptop. This worked fine, but added to the bulk necessary to run the computer. The glovebox was rendered essentially unusable, since it was full of electronices.
One issue that any carpc must deal with is turning on and off with the ignition. One option is to wire up relays to the serial port and set up autohibernation based on that. Another is to use a shutdown controller that performs the necessary functions. I bought one of these to control the Mocha, but its designed for any atx motherboard :
http://www.mp3car.com/store/product_info.php?cPath=29&products_id=58
Basically the idea is the shutdown controller monitors the ignition wire - When it goes hot because you turned on the car, it supplies power to its output (connected to the power of the PC), and shorts the switch on the motherboard that tells the PC to turn on. When you turn the car off, after a configurable delay, the controller sends the signal to the PC to have it turn off (or hibernate). After the computer has had time to power down, the shutdown controller cuts power to it's output to prevent battery drain.
Unfortunately for me, my Mocha died shortly after introducing the uSDC to the system. At that point, I decided to switch form factors. First of all, it was going into the trunk, since I was tired of all the clutter in the cabin. Second of all it had to be expandable and comprised of standard components, since when the mocha stopped working, it turned into a worthless brick and I had to start from scratch. Since I already had a small-form factor Shuttle XPC, I decided to use that.
Locating a PC in the trunk introduces an entirely new set of obstacles to overcome. The first one to deal with is wiring. PC's use a lot of wires, but the most troublesome one for a carpc install is the monitor cable. the HD15 connector that most analog monitors use is MUCH larger than the holes that you'll find in the firewall between the engine bay and trunk/passenger compartments. Since my install is somewhat experimental and changes often, one rule is that everything has to be revertable back to stock. With that in mind, there's no way I was going to enlarge the holes so they were big enough to fit the VGA cable through. One option would be to try using a VGA over ethernet adaptor. They're not cheap, need to be powered, and don't always work well. They may work fine in this situation. Another option would be to run cable without the ends and then solder connectors on the ends (leaving plenty of slack or else having to solder IN the nsx?!?). Instead, I found a cable that had a detachable end, and some smaller round connectors that actually do fit through the existing holes. Cost is about 50 bux for the two pieces of the cable you need:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1068100&CatId=420
Make sure you run the video cable first, since it wont fit through later once the hole has other cables in it!
Here's a picture of all the cables that I fit through the hole on the passenger side.
These all run through the engine bay and into the cabin through the existing hole above the passenger's right shoulder:
Power for the pc (and amp) use the hole on the drivers side, and connect to the fuse-box:
Initially when I set up the Shuttle in the trunk, I used the 120V power supply that came with it, powered by a Coleman inverter. This seemed to work fine, but I experienced some strange behavior where the video screen would lose sync and go blank intermittently (but often enough to be a problem). The problem only occured when the engine was running. Because I was having problems with my shutdown controller (see this thread I started on mp3car.com for details : http://www.mp3car.com/vbulletin/showthread.php?t=47109), I decided to purchase a 12v->12v regulated ATX power supply for the Shuttle. The Opus 150 I bought has a shutdown controller built in, so it ended up being exactly what I needed. Unfortunatly they're somewhat expensive, ~150 dollars. When I installed the Opus, I discovered that my video sync problems were gone as well! Somehow, the inverter was introducing some noise that would mess up the video signal! The lesson learned here is that it's worth it to just by a 12V regulated power supply rather than dealing with the Inverter and Shutdown controller. The cost isn't much more, and it's just a much cleaner and efficient power solution. I still use the inverter to power stuff in the cabin, and have no problems with it introducing noise - only when it was powering the PC.
Still with me?? I know this is getting lengthy, but it's been a long learning experience trying out a lot of different stuff over the last 9 months!
The next major hurdle to overcome is one that is shared with anyone who wants to locate things in their NSX trunk - HEAT! The trunk is adorned with a nice vent, covered by a rubber flap, which allows the trunk to close, since otherwise you'd be trying to compress a sealed volume. This vent leads into the fender. The side air intake behind the passenger door flows back to the engine bay fan, and continues all the way back to this vent. Merely placing a fan over this vent is a futile effort, since there needs to be somewhere to draw fresh air in.
One way to create an intake is to drill holes in your trunk in a strategic location so that air flows in and over the components to be cooled. I couldn't believe it when this antenna installer drilled into my new (to me) car to install some crappy replacement antenna. It happened too fast before I realized what had happened! I wasn't going to drill more holes, so I came up with this as a possible solution:
The idea here is that the 120mm fan is pushing hot air out the vent, while the side of the vent has a seperate port, allowing air to return, creating an exchange of air between the trunk and the fender. The obvious flaw is that the 'fresh' air is being pulled from the same place that the air is being exhausted to. I hoped that the side intake would provide outside air to the fender, allowing for some cooling of the air in the fender to take place.
This setup worked fairly well, but failed on hot days. After doing some reasearch on overclocking Shuttles (to learn advanced cooling techniques), I severely modified the Shuttle case. Here's a list of some of the modifications:
Removed front panel
Dremeled restrictive grill off over rear radiator
Removed stock 80MM exhaust fan, added ultra-thick 120MM fan with a 80-120 adaptor, dremeled to fit and reversely configured as an intake so that air is pulled in from the rear
Added 60MM fan placed over CPU block
Reversed HD orientation so thick 120MM fan would fit
Added squirrel cage blower to front to exhaust air
Added dual-fan HD cooler
Internalized front USB ports, added USB TV/FM tuner and bluetooth internally
External antenna for PCI wifi card
Squirrel Blower:
I attached an 80MM duct to the rear of the pc (which is now setup as an intake), and ran that duct to the vent. This sucks in 'fresh' air from the fender. I placed a squirrel cage blower in the opening which blows hot air into the fender to be mixed with cooler air. Here's what it looks like installed:
I added a crossflow fan to the corner of the trunk, check it out in the upper right corner of this picture:
Fresh air flows in the rear of the pc, out the front and to the side, then from the corner back to towards the vent, then through the squirrel blower out the vent! There's an actual path for air to flow, wow!
This setup works very well under almost all circumstances. However, on very hot days, after a couple hours of driving (so the system is hot), if I get stuck in traffic, the PC overheats and turns off. I believe that this is because there is no fresh air being driven into the fender when the car isn't moving. I have upgraded the system a bit since my last extended daytime drive (upgraded 80 to 120mm fan, front squirrel and crossflow fan, hd cooler, cpu block fan), so I expect some slightly better heat numbers with the current setup. However, I think that I will still run into problems on hot days when stuck at a standstill.
Here's what I think are my options for solving the remaining heat issue in the trunk. I could run a hose from the side intake on the passenger side all the way back to the air intake for the pc, which would guarantee a constant supply of fresh air, even when the car is stopped. Alternatively, I think that perhaps if I switch on the engine bay fan, then that might pull enough fresh air into the fender to keep the PC alive. Does anyone know of a convienient place to tap into the fan speed sensor? It's my understanding that grounding this should engage the fan, but when I looked at my fan, I only saw two wires running to it.
Any other ideas would be great, I'm open to any suggestions fellow nsxers may have!
Congrats if you made it all the way through, that ended up being way too long, and I even left out a lot (input devices, software, etc)! There's many more details that I'd be happy to go into, so feel free to ask!
-Josh
*disclaimers - There are many ways to build a system, and this is only one method. I don't claim that it's the best, but it works for me. You may think this is over the edge, but I'm a techy guy that breathes computers all day, so it's practically a requirement for me to outfit my daily driver like this. Distractions while driving are very dangerous, always use extra caution and NEVER watch videos while the car is in motion! Be sure you are aware of the laws regarding video screens for your state, etc. etc. etc.
First, a little background. CarPC's are nifty tools that can update a 15-year old car (or even an 05) back to gaget levels you'd want in a modern car. While offering all the features you'd find on a fully equiped headunit, the CarPC allows total flexibility and upgradablility. This flexibility comes at a price, since standard headunits are simpler and have less things that can go wrong. Introducing a PC into your system introduces a lot of complexity. There are certainly benefits for a standard headunit over a pc, and vice versa - no need to figure out what is better, since it depends on the what the user wants.
In the nsx, there's only a few spots available for locating a PC, and your choices are restricted by the size of the PC you choose. There are several form-factor options, ranging from ones that are standard DIN sizes, to Mac-Minis, mini-ITX based systems, Shuttles, Mocha/Cappucino, etc. The first PC I installed into my NSX was a Mocha PC. It's about the size of a mac mini, but has a P4.
http://www.cappuccinopc.com/mochae5042b.asp
It's small enough that you can fit it in the glovebox! I was able to tuck the wires in various crevices in such a manner that I could hook it up without needing to cut any holes in anything. Amazingly, even during long trips (6-8 hrs), it never overheated, even though it was enclosed in the glovebox the entire trip. Unfortunately, it required a 20V power supply, which is somewhat annoying to provide. My solution was to use an inverter to power a 120vac->20vdc adaptor from an old dell laptop. This worked fine, but added to the bulk necessary to run the computer. The glovebox was rendered essentially unusable, since it was full of electronices.
One issue that any carpc must deal with is turning on and off with the ignition. One option is to wire up relays to the serial port and set up autohibernation based on that. Another is to use a shutdown controller that performs the necessary functions. I bought one of these to control the Mocha, but its designed for any atx motherboard :
http://www.mp3car.com/store/product_info.php?cPath=29&products_id=58
Basically the idea is the shutdown controller monitors the ignition wire - When it goes hot because you turned on the car, it supplies power to its output (connected to the power of the PC), and shorts the switch on the motherboard that tells the PC to turn on. When you turn the car off, after a configurable delay, the controller sends the signal to the PC to have it turn off (or hibernate). After the computer has had time to power down, the shutdown controller cuts power to it's output to prevent battery drain.
Unfortunately for me, my Mocha died shortly after introducing the uSDC to the system. At that point, I decided to switch form factors. First of all, it was going into the trunk, since I was tired of all the clutter in the cabin. Second of all it had to be expandable and comprised of standard components, since when the mocha stopped working, it turned into a worthless brick and I had to start from scratch. Since I already had a small-form factor Shuttle XPC, I decided to use that.
Locating a PC in the trunk introduces an entirely new set of obstacles to overcome. The first one to deal with is wiring. PC's use a lot of wires, but the most troublesome one for a carpc install is the monitor cable. the HD15 connector that most analog monitors use is MUCH larger than the holes that you'll find in the firewall between the engine bay and trunk/passenger compartments. Since my install is somewhat experimental and changes often, one rule is that everything has to be revertable back to stock. With that in mind, there's no way I was going to enlarge the holes so they were big enough to fit the VGA cable through. One option would be to try using a VGA over ethernet adaptor. They're not cheap, need to be powered, and don't always work well. They may work fine in this situation. Another option would be to run cable without the ends and then solder connectors on the ends (leaving plenty of slack or else having to solder IN the nsx?!?). Instead, I found a cable that had a detachable end, and some smaller round connectors that actually do fit through the existing holes. Cost is about 50 bux for the two pieces of the cable you need:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1068100&CatId=420
Make sure you run the video cable first, since it wont fit through later once the hole has other cables in it!
Here's a picture of all the cables that I fit through the hole on the passenger side.
These all run through the engine bay and into the cabin through the existing hole above the passenger's right shoulder:
Power for the pc (and amp) use the hole on the drivers side, and connect to the fuse-box:
Initially when I set up the Shuttle in the trunk, I used the 120V power supply that came with it, powered by a Coleman inverter. This seemed to work fine, but I experienced some strange behavior where the video screen would lose sync and go blank intermittently (but often enough to be a problem). The problem only occured when the engine was running. Because I was having problems with my shutdown controller (see this thread I started on mp3car.com for details : http://www.mp3car.com/vbulletin/showthread.php?t=47109), I decided to purchase a 12v->12v regulated ATX power supply for the Shuttle. The Opus 150 I bought has a shutdown controller built in, so it ended up being exactly what I needed. Unfortunatly they're somewhat expensive, ~150 dollars. When I installed the Opus, I discovered that my video sync problems were gone as well! Somehow, the inverter was introducing some noise that would mess up the video signal! The lesson learned here is that it's worth it to just by a 12V regulated power supply rather than dealing with the Inverter and Shutdown controller. The cost isn't much more, and it's just a much cleaner and efficient power solution. I still use the inverter to power stuff in the cabin, and have no problems with it introducing noise - only when it was powering the PC.
Still with me?? I know this is getting lengthy, but it's been a long learning experience trying out a lot of different stuff over the last 9 months!
The next major hurdle to overcome is one that is shared with anyone who wants to locate things in their NSX trunk - HEAT! The trunk is adorned with a nice vent, covered by a rubber flap, which allows the trunk to close, since otherwise you'd be trying to compress a sealed volume. This vent leads into the fender. The side air intake behind the passenger door flows back to the engine bay fan, and continues all the way back to this vent. Merely placing a fan over this vent is a futile effort, since there needs to be somewhere to draw fresh air in.
One way to create an intake is to drill holes in your trunk in a strategic location so that air flows in and over the components to be cooled. I couldn't believe it when this antenna installer drilled into my new (to me) car to install some crappy replacement antenna. It happened too fast before I realized what had happened! I wasn't going to drill more holes, so I came up with this as a possible solution:
The idea here is that the 120mm fan is pushing hot air out the vent, while the side of the vent has a seperate port, allowing air to return, creating an exchange of air between the trunk and the fender. The obvious flaw is that the 'fresh' air is being pulled from the same place that the air is being exhausted to. I hoped that the side intake would provide outside air to the fender, allowing for some cooling of the air in the fender to take place.
This setup worked fairly well, but failed on hot days. After doing some reasearch on overclocking Shuttles (to learn advanced cooling techniques), I severely modified the Shuttle case. Here's a list of some of the modifications:
Removed front panel
Dremeled restrictive grill off over rear radiator
Removed stock 80MM exhaust fan, added ultra-thick 120MM fan with a 80-120 adaptor, dremeled to fit and reversely configured as an intake so that air is pulled in from the rear
Added 60MM fan placed over CPU block
Reversed HD orientation so thick 120MM fan would fit
Added squirrel cage blower to front to exhaust air
Added dual-fan HD cooler
Internalized front USB ports, added USB TV/FM tuner and bluetooth internally
External antenna for PCI wifi card
Squirrel Blower:
I attached an 80MM duct to the rear of the pc (which is now setup as an intake), and ran that duct to the vent. This sucks in 'fresh' air from the fender. I placed a squirrel cage blower in the opening which blows hot air into the fender to be mixed with cooler air. Here's what it looks like installed:
I added a crossflow fan to the corner of the trunk, check it out in the upper right corner of this picture:
Fresh air flows in the rear of the pc, out the front and to the side, then from the corner back to towards the vent, then through the squirrel blower out the vent! There's an actual path for air to flow, wow!
This setup works very well under almost all circumstances. However, on very hot days, after a couple hours of driving (so the system is hot), if I get stuck in traffic, the PC overheats and turns off. I believe that this is because there is no fresh air being driven into the fender when the car isn't moving. I have upgraded the system a bit since my last extended daytime drive (upgraded 80 to 120mm fan, front squirrel and crossflow fan, hd cooler, cpu block fan), so I expect some slightly better heat numbers with the current setup. However, I think that I will still run into problems on hot days when stuck at a standstill.
Here's what I think are my options for solving the remaining heat issue in the trunk. I could run a hose from the side intake on the passenger side all the way back to the air intake for the pc, which would guarantee a constant supply of fresh air, even when the car is stopped. Alternatively, I think that perhaps if I switch on the engine bay fan, then that might pull enough fresh air into the fender to keep the PC alive. Does anyone know of a convienient place to tap into the fan speed sensor? It's my understanding that grounding this should engage the fan, but when I looked at my fan, I only saw two wires running to it.
Any other ideas would be great, I'm open to any suggestions fellow nsxers may have!
Congrats if you made it all the way through, that ended up being way too long, and I even left out a lot (input devices, software, etc)! There's many more details that I'd be happy to go into, so feel free to ask!
-Josh
*disclaimers - There are many ways to build a system, and this is only one method. I don't claim that it's the best, but it works for me. You may think this is over the edge, but I'm a techy guy that breathes computers all day, so it's practically a requirement for me to outfit my daily driver like this. Distractions while driving are very dangerous, always use extra caution and NEVER watch videos while the car is in motion! Be sure you are aware of the laws regarding video screens for your state, etc. etc. etc.
