Cold air box thought
06-06-06, 05:29 PM
#26
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^ impressive
Well it looks like im just going to go ahead and do it. If it can give me .0025% of a horsepower increase... thats fine with me.. becuase its summer, and im bored. I dont have my car back yet (hoping for this weekend) but when i do im going to start making a template and figuring this up.
Well it looks like im just going to go ahead and do it. If it can give me .0025% of a horsepower increase... thats fine with me.. becuase its summer, and im bored. I dont have my car back yet (hoping for this weekend) but when i do im going to start making a template and figuring this up.
06-06-06, 06:30 PM
#27
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The idea of convection is really where the "free" and best (easiest) gain would be realised. what needs to be done with this shell is that you need to have an inlet at a pressurized intake area and have the top open to the engine bay and convection will keep cool air coming in keeping heatsoak from becoming an issue (unless left idling or in heavy traffic) it will also keep the inner box cool as the air flows through it.
Next thought process, a pre chiller can be made in the air stream using a water pump and 1 small coil (water) and a bigger coil mounted in front of the radiator to chill the water before it recycles to the coil in the path of the intake airflow. You can take it one step farther with the addition of copressed air cylinder on an actuator set up to operate however and whenever you choose. The compressed air will be directed over the coil surface to further chill the coil in the intake airstream and introduce very cold air into the airstream as well. Another step farther would be to run the chiller water through a 6" +- rectangular box that can be opened to fill with ice before that 1 run. Inside the box 3/4" before the exit would need to be an 1/8" screen to hold the ice from clogging the line.
A word of caution when chilling air. When you chill the air it becomes denser with more O2 which results in a leaner condition if you do not adjust fuel flow to accomodate this condition it could become a problem. This would be more of a problem in a car that is well tuned as we usually run a little rich with a stock setup anyway.
These ideas are just small increases but when all done together the increases do add up.
Disclaimer: not responsible for you running your engine too lean from air being too cold and too dense. Appropriate measures should always be taken to ensure proper AF ratios.
Next thought process, a pre chiller can be made in the air stream using a water pump and 1 small coil (water) and a bigger coil mounted in front of the radiator to chill the water before it recycles to the coil in the path of the intake airflow. You can take it one step farther with the addition of copressed air cylinder on an actuator set up to operate however and whenever you choose. The compressed air will be directed over the coil surface to further chill the coil in the intake airstream and introduce very cold air into the airstream as well. Another step farther would be to run the chiller water through a 6" +- rectangular box that can be opened to fill with ice before that 1 run. Inside the box 3/4" before the exit would need to be an 1/8" screen to hold the ice from clogging the line.
A word of caution when chilling air. When you chill the air it becomes denser with more O2 which results in a leaner condition if you do not adjust fuel flow to accomodate this condition it could become a problem. This would be more of a problem in a car that is well tuned as we usually run a little rich with a stock setup anyway.
These ideas are just small increases but when all done together the increases do add up.
Disclaimer: not responsible for you running your engine too lean from air being too cold and too dense. Appropriate measures should always be taken to ensure proper AF ratios.
06-06-06, 07:20 PM
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what about a loop that sucks the air around the box (to keep it moving and prevent heat soak) and into the filter chamber? would the air get too hot moving throught the outside chamber?
and no seiously, someone search for vortex tubes and see what it looks like
looks like theres one small enough, and a small portable air compressor, working of your battery produces more than enough psi,
then just direct the cold air into or around your box?
and the a.c idea was really not for a pulley, but a light, eletric a/c compressor whch coul run off batt power.
GOOD INFO from the engineer and Tinvestor tho thanks!!!!!!!!
and no seiously, someone search for vortex tubes and see what it looks like
looks like theres one small enough, and a small portable air compressor, working of your battery produces more than enough psi,
then just direct the cold air into or around your box?
and the a.c idea was really not for a pulley, but a light, eletric a/c compressor whch coul run off batt power.
GOOD INFO from the engineer and Tinvestor tho thanks!!!!!!!!
06-07-06, 03:16 PM
#29
Sucking air around the box would just bring in warm air. Heat build up around the intake is only a problem if that warmth gets into your intake, which is what you're helping when you suck that air into your intake. A better option would be to increase the airflow through the box (dumping the extra cold air out the back or to the side) or insulate the box better.
The electric A/C I used in my calcs weighs about 50lbs., it's about 2'x1.5'x1.5' and it's barely powerful enough to chill the air by 15F. At 400W (45A) power consumption it would also hurt your mileage (maybe -1mpg).
The electric A/C I used in my calcs weighs about 50lbs., it's about 2'x1.5'x1.5' and it's barely powerful enough to chill the air by 15F. At 400W (45A) power consumption it would also hurt your mileage (maybe -1mpg).
06-07-06, 03:54 PM
#30
And the Revolution...
I made my box out of thin steel and Insulated the inside of it with this silver bubble wrap type stuff from lowes. And I have my FTP lenses taken out bringing in a little cool air. I also have a few holes drilled right in front of the filter to allow the cool air into the box. I've been wanting to get a nice vented headlight cover but its been working good so far. I don't know of any reduction in temps but in my head it works good. Insulate filter/box from heat, supply with fresh air, BOOM cold air box. And you don't have to let the extra cold air circulate anywhere because its being sucked in by the filter, the main thing a cold air box does is insulate from the engine heat.
06-07-06, 04:48 PM
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[QUOTE=ericgrau]Sucking air around the box would just bring in warm air. Heat build up around the intake is only a problem if that warmth gets into your intake, which is what you're helping when you suck that air into your intake. A better option would be to increase the airflow through the box (dumping the extra cold air out the back or to the side) or insulate the box better.
Yes that is precisely what I said. Part of the intake air in the high pressure intake area (wherever you choose to put it) is diverted into the shell and a small opening is left in the top rear of the shell in order to allow this small amount of air to flow into the engine bay.
[QUOTE=DarkKnightFC]you don't have to let the extra cold air circulate anywhere because its being sucked in by the filter, the main thing a cold air box does is insulate from the engine heat.
The idea of letting EXTRA air (keep in mind this air is from outside) flow through the box is to keep an air gap, which is an insulator, of fresh cool air which prevents heat soak.
Yes that is precisely what I said. Part of the intake air in the high pressure intake area (wherever you choose to put it) is diverted into the shell and a small opening is left in the top rear of the shell in order to allow this small amount of air to flow into the engine bay.
[QUOTE=DarkKnightFC]you don't have to let the extra cold air circulate anywhere because its being sucked in by the filter, the main thing a cold air box does is insulate from the engine heat.
The idea of letting EXTRA air (keep in mind this air is from outside) flow through the box is to keep an air gap, which is an insulator, of fresh cool air which prevents heat soak.
06-07-06, 05:06 PM
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Originally Posted by DarkKnightFC
And I have my FTP lenses taken out bringing in a little cool air.
06-07-06, 06:41 PM
#33
And the Revolution...
I wouldn't imagine that they HAVE to. It seems like a little air would make it back there anyway seeing as how most of the time its a 60 mile an hour wind or more thats trying to shove air in there. As I said, it works in my head right now, But I would have to do a temp test with headlights up, down, and after its been sitting for a while to get hard evidence. I just don't have that kind of time lately. The box has been on there for 6 months or more and I'll eventually do something a little more PRETTY like a Vinspeed airbox. But for now its doing a good job in my head. 
06-07-06, 06:46 PM
#34
And the Revolution...
[QUOTE=tinvestor][QUOTE=ericgrau]Sucking air around the box would just bring in warm air. Heat build up around the intake is only a problem if that warmth gets into your intake, which is what you're helping when you suck that air into your intake. A better option would be to increase the airflow through the box (dumping the extra cold air out the back or to the side) or insulate the box better.
Yes that is precisely what I said. Part of the intake air in the high pressure intake area (wherever you choose to put it) is diverted into the shell and a small opening is left in the top rear of the shell in order to allow this small amount of air to flow into the engine bay.
The air gap that you're speaking of would be between the 2 layers of the air box? If thats the case then I wouldn't even make 2 layers. I would just insulate the inside of the box which is one sheet of metal. Which is ultimately what I did. If you really wanted to know it was being insulated then you could buy some of that insulation sheets that Jegs or Summit sells, I think its DEI maybe. That might be a little overkill because its for insulating exhaust but its up to you.
Yes that is precisely what I said. Part of the intake air in the high pressure intake area (wherever you choose to put it) is diverted into the shell and a small opening is left in the top rear of the shell in order to allow this small amount of air to flow into the engine bay.
Originally Posted by DarkKnightFC
you don't have to let the extra cold air circulate anywhere because its being sucked in by the filter, the main thing a cold air box does is insulate from the engine heat.
The idea of letting EXTRA air (keep in mind this air is from outside) flow through the box is to keep an air gap, which is an insulator, of fresh cool air which prevents heat soak.
The idea of letting EXTRA air (keep in mind this air is from outside) flow through the box is to keep an air gap, which is an insulator, of fresh cool air which prevents heat soak.
The air gap that you're speaking of would be between the 2 layers of the air box? If thats the case then I wouldn't even make 2 layers. I would just insulate the inside of the box which is one sheet of metal. Which is ultimately what I did. If you really wanted to know it was being insulated then you could buy some of that insulation sheets that Jegs or Summit sells, I think its DEI maybe. That might be a little overkill because its for insulating exhaust but its up to you.
06-07-06, 09:05 PM
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hey so after reading all of this i decided to go check out my car, since i already have the lenses removed on my car though it see how much cold air would get to where the filter and stuff was but check this: i have a 1989 GTU, im not sure if its any different with other models because mine seems to be the *hardest to find correct parts for* and stuff but this is what i found, headlight bay is completly blocked off from top to bottom, no holes or openings, no air would be able to get to the engine bay even with the lenses removed. here are some pics.
in this last image it may look like there may be a small opening at the top but it was just the way the picture was taken, there are no openings.
anybody's elses different?
in this last image it may look like there may be a small opening at the top but it was just the way the picture was taken, there are no openings.
anybody's elses different?
06-07-06, 09:51 PM
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Originally Posted by 2RICE4U
No there all like that, Icemark has told so many people that:P
06-07-06, 10:03 PM
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Originally Posted by DarkKnightFC
The air gap that you're speaking of would be between the 2 layers of the air box? If thats the case then I wouldn't even make 2 layers. I would just insulate the inside of the box which is one sheet of metal. Which is ultimately what I did. If you really wanted to know it was being insulated then you could buy some of that insulation sheets that Jegs or Summit sells, I think its DEI maybe. That might be a little overkill because its for insulating exhaust but its up to you.
06-08-06, 08:53 PM
#40
And the Revolution...
The answer would be to drill some small holes like I did which allow the filter to get some cold air, Because I can look right thru the FTP hole and see my filter thru the holes. And insulate the box to keep it from getting heat soak. If theres always cool air coming in there's absolutely no way it can heatsoak with the insulation.
Chri
Chri
06-11-06, 11:35 PM
#41
Originally Posted by ericgrau
This looks like a job for... (toy soldier blows trumpet) a UC Berkeley mechanical engineering student.
COLD AIR BOX INSULATION
Air is a great insulator. Air moves heat through convection (fluid motion), not conduction (still fluid or object, moving heat). So if you can stop the air from moving, you'll be in pretty good shape already. A cold air box made of sheet aluminum should do just fine. If you're still concerned, put a little fiberglass insulation around it. But what's more important is to seal it off really well from the air under your hood to stop convection. I've seen pics of some nice looking cold air boxes with rubber seals that push into the hood above them.
AIR CONDITIONED INTAKE?
I calculated earlier that an ideal cold air intake would yield 8HP on a stock N/A. A forum member revealed that real cold air intakes get about 7HP. Not bad considering I had no idea what kind of power a real cold intake yielded. According to my calcs, every 1 degree fahrenheit yields an 0.2% boost in horsepower (so you get even more HP on, for example, a tricked out turbo).
Let's see what kind of A/C we need. A rotary displaces 1.3L every revolution. So at 6500rpm we have 1.3L x 6500rpm /(60s/m) = 140.8L/s (290cfm) of air to cool.
140.8L/s * 1m^3/(1000L)*0.8kg/m^3 * 1000J/kg*C = 112.64(J/s)/C = 112.64W/C (214 Btu/hr*F)
I'm guessing you could get about 20F out of a common A/C, which means you need 214*20 = 4280Btu/hr. What a coincidence, that's just what a common window A/C produces. But wait, you can't get 20F and max Btus; it's usually either-or. So let's say 15F and 3200Btu/hr, to be more reasonable. That gives you a 3% boost in power, or a little over 4HP on an N/A. Power consumption on these things is about 500W, or 2/3HP. So you're left with about 3.5HP. But wait, adding that 50 pound window A/C is the same as losing 2.5HP. So you're left with a 1HP gain. Not to mention another 45A on your alternator. What if you don't want to use R134a or freon? What if you want to use something colder? I've calculated that out before, and the power consumption gets pretty ridiculous.
It makes sense. After all, an A/C works with a compressor. Why not just compress air instead and pump that into your engine? (i.e., use a turbocharger). Still, I think a tank of compressed air might work in short bursts. At 3000psi a 2L tank can hold 200L of gas, enough to last you 1.4s. But the air will be freezing cold. I don't remember how cold, but assuming -30F you'd get a 20% boost in horsepower. For 1.4 seconds you could also boost horsepower by up to 360% with pure compressed oxygen, but I'm certain your engine would blow up first... in a spectacular explosion. And if you're going to do all that, why not go with nitrous?
For those of you that fell asleep. An A/C consumes almost as much horsepower to run than it gives. And since it runs using a compressor, why not put a turbo in instead? A bottle of compressed air lasts a couple seconds and increases HP by 20%, but then why not go nitrous? Read above blurb on cold air box and stick with that.
Disclaimer: this is all theory, not practice. Reality may be a little different, but at least it gives you an idea... unless I screwed up a calculation.
COLD AIR BOX INSULATION
Air is a great insulator. Air moves heat through convection (fluid motion), not conduction (still fluid or object, moving heat). So if you can stop the air from moving, you'll be in pretty good shape already. A cold air box made of sheet aluminum should do just fine. If you're still concerned, put a little fiberglass insulation around it. But what's more important is to seal it off really well from the air under your hood to stop convection. I've seen pics of some nice looking cold air boxes with rubber seals that push into the hood above them.
AIR CONDITIONED INTAKE?
I calculated earlier that an ideal cold air intake would yield 8HP on a stock N/A. A forum member revealed that real cold air intakes get about 7HP. Not bad considering I had no idea what kind of power a real cold intake yielded. According to my calcs, every 1 degree fahrenheit yields an 0.2% boost in horsepower (so you get even more HP on, for example, a tricked out turbo).
Let's see what kind of A/C we need. A rotary displaces 1.3L every revolution. So at 6500rpm we have 1.3L x 6500rpm /(60s/m) = 140.8L/s (290cfm) of air to cool.
140.8L/s * 1m^3/(1000L)*0.8kg/m^3 * 1000J/kg*C = 112.64(J/s)/C = 112.64W/C (214 Btu/hr*F)
I'm guessing you could get about 20F out of a common A/C, which means you need 214*20 = 4280Btu/hr. What a coincidence, that's just what a common window A/C produces. But wait, you can't get 20F and max Btus; it's usually either-or. So let's say 15F and 3200Btu/hr, to be more reasonable. That gives you a 3% boost in power, or a little over 4HP on an N/A. Power consumption on these things is about 500W, or 2/3HP. So you're left with about 3.5HP. But wait, adding that 50 pound window A/C is the same as losing 2.5HP. So you're left with a 1HP gain. Not to mention another 45A on your alternator. What if you don't want to use R134a or freon? What if you want to use something colder? I've calculated that out before, and the power consumption gets pretty ridiculous.
It makes sense. After all, an A/C works with a compressor. Why not just compress air instead and pump that into your engine? (i.e., use a turbocharger). Still, I think a tank of compressed air might work in short bursts. At 3000psi a 2L tank can hold 200L of gas, enough to last you 1.4s. But the air will be freezing cold. I don't remember how cold, but assuming -30F you'd get a 20% boost in horsepower. For 1.4 seconds you could also boost horsepower by up to 360% with pure compressed oxygen, but I'm certain your engine would blow up first... in a spectacular explosion. And if you're going to do all that, why not go with nitrous?
For those of you that fell asleep. An A/C consumes almost as much horsepower to run than it gives. And since it runs using a compressor, why not put a turbo in instead? A bottle of compressed air lasts a couple seconds and increases HP by 20%, but then why not go nitrous? Read above blurb on cold air box and stick with that.
Disclaimer: this is all theory, not practice. Reality may be a little different, but at least it gives you an idea... unless I screwed up a calculation.
06-12-06, 01:48 AM
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ok, assuming that you ould keep air flowing around the box and venting to the engine bay, it would prevent heatsoak to a much greater degree than anything else right? so the temp of the CAB is the outside temp?
anyone know how much draw a portable 9v or 12v air compressor would have on the alternator? and anyone know the nubers on an s4 n/a air flow rate, i. e . how much air the engine sucks in at different rpm/s (trying to figure out how fast air in box would hav to be chilled in order to meent demands of the engine?
anyone know how much draw a portable 9v or 12v air compressor would have on the alternator? and anyone know the nubers on an s4 n/a air flow rate, i. e . how much air the engine sucks in at different rpm/s (trying to figure out how fast air in box would hav to be chilled in order to meent demands of the engine?
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