Why are aftermarket intakes made of metal?
#21
Originally Posted by davedavetC
aluminum is really good when it comes to heat. take a sheet of aluminum foil and put it in the oven at 400 degrees for a while and then take it out. it get cool really fast. which would make sense to make a cai outta al because it has a high heat compacity (correct me if im wrong to use heat compacity). im pretty sure about all that too (im a chemistry major in college right now) but that would be my guess.
the reason that foil is easy to handle out of the oven is because it is very thin. As you might remember from physics class heat and temperature is different. Temperature is the average amout of heat in an object. A good intake matirial has to be a good insulator of the engine heat. what kind of material is that? I dont know, im not a scientist
#22
Ok guys,
Everyone needz a walk through in heat (thermal energy) transfer. The two methods you are talking about are heat conduction and heat convection. Metal is a great conductor of heat. So yes, heat will be transferred to the nozzle of the CAI from the engine bay. Additionally heat will be dispersed from a metal exhaust. Think of this as baking in an oven with a METAL pan. Another example of heat CONDUCTION is your radiator, which passes ethylene glycol and water around the internal surface of your engine (not inside the combustion chambers silly). Ever wonder here "Chevron" comes from?? Dual plated heat exchangers, where the plates have that "V" design in them to aide in mixing.
Heat convection works via air currents (yes "hot to cold" <------those terms are relative not scientific). So you have to take into account the volume and velocity of cold air into the intake and the hot refuse out of the exhaust. You can think of this system as a heat exchanger, much like baking in an oven with glass. Again, lets go back to our radiator. The "grill" of your radiator transfers thermal energy via heat convection, passing ambient (outside) air over its surface.
Back to convection --------> Now each liter of air can only hold a specific amount of heat. If we use metrics (cause its easier, we measure heat in kilojoules). In the english system, its calories. You also have to take into account the heat transfer coefficient of the material. Additionally you must consider the amount of surface area the CAI or exhaust is exposed to ambient air, as well as the temp of the ambient air. The greater the temp. difference the more effective the heat transfer.
These are all the factors that effect the heat transfer of our cars. Heat convection is the MAJOR method for our CAI, and exhaust. Why, because BOTH have a velocity associated with them, and use turbulent air. If the air flow was laminar conduction would be the dominant factor. Some heat transfer occurs via conduction but most occurs via convection.
Sorry if this is too technical, but I didn't include any mathematical formulas, which isn't FUN and requires me to write a friggan text book. Now, think how this applies to an intercooler?!?!?
-------> I can't believe my engineering degree is actually worth something (any Bill Nye jokes and u will get PIMP slapped !!!)
Everyone needz a walk through in heat (thermal energy) transfer. The two methods you are talking about are heat conduction and heat convection. Metal is a great conductor of heat. So yes, heat will be transferred to the nozzle of the CAI from the engine bay. Additionally heat will be dispersed from a metal exhaust. Think of this as baking in an oven with a METAL pan. Another example of heat CONDUCTION is your radiator, which passes ethylene glycol and water around the internal surface of your engine (not inside the combustion chambers silly). Ever wonder here "Chevron" comes from?? Dual plated heat exchangers, where the plates have that "V" design in them to aide in mixing.
Heat convection works via air currents (yes "hot to cold" <------those terms are relative not scientific). So you have to take into account the volume and velocity of cold air into the intake and the hot refuse out of the exhaust. You can think of this system as a heat exchanger, much like baking in an oven with glass. Again, lets go back to our radiator. The "grill" of your radiator transfers thermal energy via heat convection, passing ambient (outside) air over its surface.
Back to convection --------> Now each liter of air can only hold a specific amount of heat. If we use metrics (cause its easier, we measure heat in kilojoules). In the english system, its calories. You also have to take into account the heat transfer coefficient of the material. Additionally you must consider the amount of surface area the CAI or exhaust is exposed to ambient air, as well as the temp of the ambient air. The greater the temp. difference the more effective the heat transfer.
These are all the factors that effect the heat transfer of our cars. Heat convection is the MAJOR method for our CAI, and exhaust. Why, because BOTH have a velocity associated with them, and use turbulent air. If the air flow was laminar conduction would be the dominant factor. Some heat transfer occurs via conduction but most occurs via convection.
Sorry if this is too technical, but I didn't include any mathematical formulas, which isn't FUN and requires me to write a friggan text book. Now, think how this applies to an intercooler?!?!?
-------> I can't believe my engineering degree is actually worth something (any Bill Nye jokes and u will get PIMP slapped !!!)
#23
I cant believe it CAN make a difference. Have you ever felt how fast the air actually moves through the intake. Take off your filter, put your hand next to the opening and have someone step on the gas. It REALLY moves the air through. It can even be argued that engines are nothing more than glorified air pumps. The more air you can move through an engine the more power it makes. The velocity of air through your intake is way too fast to pick up a noticeable increase in temperture. It simply isnt in the intake tube long enough to warm up a signifigant amount. I can defenitely see the difference between SR and CAI since the source air temp can make a difference. I would really like to see an experiment done seeing what temperatures are required to heat air moving through a 3 foot tube at 30 - 40 mph. 30 miles/ hr is equal to 44ft/second. Even as little as 5mph = 7.33 feet per second. That means air in the intake tube for a ridiculously short amount of time..were talking miliseconds here... and it simply cant heat up in that amount of time.
Anybody else see my logic there?
BTW : cla9614 word to my south bay scion homie
Anybody else see my logic there?
BTW : cla9614 word to my south bay scion homie
#24
i read in a magazine that aftermarket intake tubes are made of metals because metals resist expansion due to heat better than plastic or rubber.
for those who think aluminum intakes get hotter than rubber or plastic ones, the misconception comes from metals being "hotter" to touch. wood flooring feels colder to walk on than carpet in the winter not because it is actually colder. in the same room, carpet and flooring is, of course, at the same room temperature. It feels colder because of its conductivity.
for those who think aluminum intakes get hotter than rubber or plastic ones, the misconception comes from metals being "hotter" to touch. wood flooring feels colder to walk on than carpet in the winter not because it is actually colder. in the same room, carpet and flooring is, of course, at the same room temperature. It feels colder because of its conductivity.
#25
Originally Posted by itimebomb
ever put aluminum foil in the oven before? not really easy to heat and cools VERY well...
Originally Posted by davedavetC
aluminum is really good when it comes to heat. take a sheet of aluminum foil and put it in the oven at 400 degrees for a while and then take it out. it get cool really fast. which would make sense to make a cai outta al because it has a high heat compacity (correct me if im wrong to use heat compacity). im pretty sure about all that too (im a chemistry major in college right now) but that would be my guess.
#26
People,
"hotness" and "coldness" are relative terms that talk about thermanl energy. They aren't scientific. Ask yourselves which has MORE thermal energy aka which is hotter a burning match or a giant ice berg? Believe it or not the ice berg has MORE thermal energy because of the amount of mass. A match that is lit burns and has a lot of thermal energy relative to its size, but can't compete with an ice berg.
Ok now temperature:
Temperature is a measurement of the AVERAGE THERMAL ENERGY of an object. Its saying that for all of the grams (mass) that comprise an object this is the average amount of thermal energy per gram; measured in (Celsuis). THATS all, its your basic AVERAGE !!!!
"hotness" and "coldness" are relative terms that talk about thermanl energy. They aren't scientific. Ask yourselves which has MORE thermal energy aka which is hotter a burning match or a giant ice berg? Believe it or not the ice berg has MORE thermal energy because of the amount of mass. A match that is lit burns and has a lot of thermal energy relative to its size, but can't compete with an ice berg.
Ok now temperature:
Temperature is a measurement of the AVERAGE THERMAL ENERGY of an object. Its saying that for all of the grams (mass) that comprise an object this is the average amount of thermal energy per gram; measured in (Celsuis). THATS all, its your basic AVERAGE !!!!
#27
when air is traveling through a metal, aluminized piping it's going in a vortech spinning motion.. the plastic could be in the same clean state as a metal pipe but it'll never generate that motion. that spinning motion allows faster airflow.
as for heat.. the air travels so fast through that damn pipe, that .000002 seconds it's in there, it'll never heat up. also on short ram intakes, once traveling 10...20miles an hour, that damn intake sucks in all that heat once.. after that believe it or not it's only cold air it's picking up. once in motion it's just fine. it's terrible at a red light.. sitting there in 90o weather waiting for the light to change.. but thats fine also once u start moving.
<<works in the HVAC industry!
as for heat.. the air travels so fast through that damn pipe, that .000002 seconds it's in there, it'll never heat up. also on short ram intakes, once traveling 10...20miles an hour, that damn intake sucks in all that heat once.. after that believe it or not it's only cold air it's picking up. once in motion it's just fine. it's terrible at a red light.. sitting there in 90o weather waiting for the light to change.. but thats fine also once u start moving.
<<works in the HVAC industry!
#28
Originally Posted by cla9614
-------> I can't believe my engineering degree is actually worth something (any Bill Nye jokes and u will get PIMP slapped !!!)
#29
this is my own theory:
Intake tubing is better made out of metal because of the rigidity. The air, which does form a suction, is moving through the tube. If the tube is stock plastic, it may collapse slightly altering the movement of the air. In a metal tube, the air WILL NOT be able to collapse the tube at all meaning it would flow more uniformly and at a higher velocity.....
Like I said, that is my theory....
Intake tubing is better made out of metal because of the rigidity. The air, which does form a suction, is moving through the tube. If the tube is stock plastic, it may collapse slightly altering the movement of the air. In a metal tube, the air WILL NOT be able to collapse the tube at all meaning it would flow more uniformly and at a higher velocity.....
Like I said, that is my theory....
#30
Originally Posted by SCI_TC_GUY
this is my own theory:
Intake tubing is better made out of metal because of the rigidity. The air, which does form a suction, is moving through the tube. If the tube is stock plastic, it may collapse slightly altering the movement of the air. In a metal tube, the air WILL NOT be able to collapse the tube at all meaning it would flow more uniformly and at a higher velocity.....
Like I said, that is my theory....
Intake tubing is better made out of metal because of the rigidity. The air, which does form a suction, is moving through the tube. If the tube is stock plastic, it may collapse slightly altering the movement of the air. In a metal tube, the air WILL NOT be able to collapse the tube at all meaning it would flow more uniformly and at a higher velocity.....
Like I said, that is my theory....
#31
Originally Posted by Mr.Superman
its not a cold-air intake because its made of aluminum and difuses heat quickly. its a cold air intake when it takes the air from the fender, away from the motor, which is much cooler/colder.
Aluminum is a lousy emmiter of heat, when compaired to other metals. If you don't believe me, then ask someone who welds both aluminum and steel. They will tell you that aluminunm stays hot very much longer than steel. More yet, you're more likely to burn your hand by picking up a piece of reciently welded aluminum. That's because the aluminum doesn't radiate the heat; you won't feel that it's hot untill it's too late. On the other hand, you will know that freshly welded steel is hot the minute you hand gets anywhere near it.
Think about it. Have you ever seen RED HOT aluminum? No! Because it doesn't radiate.
The property that measures how well a material radiates is called it's emissivity. Low number does not, high number does. Polished aluminum has an emissivity of about 0.03, while steel/iron is over 0.65. You can improve the emissivity of aluminum by changing it's surface properties. E.G. Black anodized aluminum has an emissivity of about 0.84
So if you really want your CAI to disipate heat. Either have an aluminum one anodized, or make one out of mild steel.
#32
Originally Posted by Crafter
as for heat.. the air travels so fast through that damn pipe, that .000002 seconds it's in there, it'll never heat up. also on short ram intakes, once traveling 10...20miles an hour, that damn intake sucks in all that heat once.. after that believe it or not it's only cold air it's picking up. once in motion it's just fine. it's terrible at a red light.. sitting there in 90o weather waiting for the light to change.. but thats fine also once u start moving.
<<works in the HVAC industry!
In basic terms, a 10º decrease in intake temps will result in a 1% increase in power, and vice versa. Once the car is moving, the difference in air temp between a SRI and a CAI is usually 2-3º F. Not even worth mentioning. Unless the entire engine compartment is basically sealed from the outside, a CAI won't do much. It uses the longer pipe length to optimize breathing at high RPMs, in exchange for loss of efficiency at low RPMs. You give and you get. The temp of the air itself is unimportant.
#33
Originally Posted by The Instigator
I cant believe it CAN make a difference. Have you ever felt how fast the air actually moves through the intake. Take off your filter, put your hand next to the opening and have someone step on the gas. It REALLY moves the air through. It can even be argued that engines are nothing more than glorified air pumps. The more air you can move through an engine the more power it makes. The velocity of air through your intake is way too fast to pick up a noticeable increase in temperture. It simply isnt in the intake tube long enough to warm up a signifigant amount. I can defenitely see the difference between SR and CAI since the source air temp can make a difference. I would really like to see an experiment done seeing what temperatures are required to heat air moving through a 3 foot tube at 30 - 40 mph. 30 miles/ hr is equal to 44ft/second. Even as little as 5mph = 7.33 feet per second. That means air in the intake tube for a ridiculously short amount of time..were talking miliseconds here... and it simply cant heat up in that amount of time.
Anybody else see my logic there?
BTW : cla9614 word to my south bay scion homie
Anybody else see my logic there?
BTW : cla9614 word to my south bay scion homie
#34
Instead of everyone talking out of their ___, why don’t you take a few minutes to read up on the subject here: http://okfirst.ocs.ou.edu/train/mete...tTransfer.html
You can use any or all of the principals of conduction, convection, radiation, or evaporation to get cooler (thus more dense, thus more oxygen into your engine)
Conduction: Use very thick walled pipes, they’ll hold more heat. But once they’re warm, they’re NFG. Besides, they’ll be heavier.
Convection: True that air is a lousy conductor, but on the molecular level and against a conducting surface, it exchanges the heat very well. Problem is that the distance between molecules is huge compared to their size, which is why it doesn’t conduct. So, unless air is able to move, it looses/gains the heat only at the interface with whatever it’s touching. That’s why the person who said the air was moving too fast to loose/gain heat has it wrong – movement is good – faster is better.
Radiation: Anyone who’s been near a ceramic heater, toaster, or black car on a sunny day. Should get the clue that radiative exchange is a major way to disperse heat.
Evaporation: This one will get the job done, which is why they have fan driven misters blowing onto the lines in an amusement park. It cools things by converting thermal energy into kinetic energy. AKA, Heat of Evaporation.
So – to get a good heat exchanger – you should increase the surface area, for better convection, by using fins. Paint it black (anodize it for Aluminum) for best radiation. And, mist it with water.
But here’s the real news for all Scion owners (at least at this point in time). Unless the air inside the tube is hotter than the air outside (like with turbos or a supercharger) then the best heat exchanger in the world does you little to NFG. Without a deltaT, there is no heat exchange. The only part of the system I described above that would do anything is misting the pipe with water. That creates it’s own deltaT via energy conversion.
So, the ones who said the CIA is aluminum because it is ridged, hit it right on the nose. The hard pipe improves the mass flow rate. So it’s more air, but it ain’t a damn bit cooler.
You can use any or all of the principals of conduction, convection, radiation, or evaporation to get cooler (thus more dense, thus more oxygen into your engine)
Conduction: Use very thick walled pipes, they’ll hold more heat. But once they’re warm, they’re NFG. Besides, they’ll be heavier.
Convection: True that air is a lousy conductor, but on the molecular level and against a conducting surface, it exchanges the heat very well. Problem is that the distance between molecules is huge compared to their size, which is why it doesn’t conduct. So, unless air is able to move, it looses/gains the heat only at the interface with whatever it’s touching. That’s why the person who said the air was moving too fast to loose/gain heat has it wrong – movement is good – faster is better.
Radiation: Anyone who’s been near a ceramic heater, toaster, or black car on a sunny day. Should get the clue that radiative exchange is a major way to disperse heat.
Evaporation: This one will get the job done, which is why they have fan driven misters blowing onto the lines in an amusement park. It cools things by converting thermal energy into kinetic energy. AKA, Heat of Evaporation.
So – to get a good heat exchanger – you should increase the surface area, for better convection, by using fins. Paint it black (anodize it for Aluminum) for best radiation. And, mist it with water.
But here’s the real news for all Scion owners (at least at this point in time). Unless the air inside the tube is hotter than the air outside (like with turbos or a supercharger) then the best heat exchanger in the world does you little to NFG. Without a deltaT, there is no heat exchange. The only part of the system I described above that would do anything is misting the pipe with water. That creates it’s own deltaT via energy conversion.
So, the ones who said the CIA is aluminum because it is ridged, hit it right on the nose. The hard pipe improves the mass flow rate. So it’s more air, but it ain’t a damn bit cooler.
#36
Originally Posted by Casus_Belli
Instead of everyone talking out of their ___, why don’t you take a few minutes to read up on the subject here:
Dude,
I promise you that I wasn't talking out of my ___ . I really did study engineering in college.
#37
Originally Posted by cla9614
Originally Posted by Casus_Belli
Instead of everyone talking out of their ___, why don’t you take a few minutes to read up on the subject here:
Dude,
I promise you that I wasn't talking out of my ___ . I really did study engineering in college.
#38
Originally Posted by Dr. Isotope
Originally Posted by Crafter
as for heat.. the air travels so fast through that damn pipe, that .000002 seconds it's in there, it'll never heat up. also on short ram intakes, once traveling 10...20miles an hour, that damn intake sucks in all that heat once.. after that believe it or not it's only cold air it's picking up. once in motion it's just fine. it's terrible at a red light.. sitting there in 90o weather waiting for the light to change.. but thats fine also once u start moving.
<<works in the HVAC industry!
In basic terms, a 10º decrease in intake temps will result in a 1% increase in power, and vice versa. Once the car is moving, the difference in air temp between a SRI and a CAI is usually 2-3º F. Not even worth mentioning. Unless the entire engine compartment is basically sealed from the outside, a CAI won't do much. It uses the longer pipe length to optimize breathing at high RPMs, in exchange for loss of efficiency at low RPMs. You give and you get. The temp of the air itself is unimportant.
#39
Originally Posted by The Instigator
Aluminum is also cheap, readily available and very easy to work with.