reagulator

the term you were looking for is specific heat capacity.(close enough)

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

cla9614

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 !!!)

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

hnefrdo

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.

hnefrdo

are you guys suggesting that intakes should be wrapped in foil??

cla9614

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 !!!!

Crafter

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!

Souljah347

i was going to say Mr. Wizard.... man i miss that show

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....

The_Instigator

Maybe with a turbo pulling 30 psi with a clogged filter...with a stock engine...nooo way. Look at the stock intake. Its soft rubber you can squeeze together with your hands and it holds its shape just fine.

Casus_Belli

This seems to be popular opinion here; only problem is it's wrong, dead wrong.

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.

Dr_Isotope

iTrader: (1)

This fellow is absolutely correct. No formulas needed.

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.

The_Instigator

Did nobody read this...you cant heat up the air in the short amount of time its in the tube. Air is a horrible conducter of heat to begin with. If you were able to pick up even 1/2 a degree on the way through the tube I would be shocked.

Casus_Belli

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.

The_Instigator

Aluminum is also cheap, readily available and very easy to work with.

cla9614

Dude,

I promise you that I wasn't talking out of my ___ . I really did study engineering in college.

davedavetC

iTrader: (4)

yea i believe cla9614, im a chemistry major in college right now, considering im only a freshman and im not a genious or anything, but 90% of the stuff he said makes sense, and i wasnt trying to get at the point that we should be wrapping our intakes in foil, im just saying that it makes more sense to make intakes out of metal because is just plain senseable. im not gonna go throw a long speach about why because cla9614 (Bill Nye haha)(jK)( go ahead try and pimp slap me watch what happens jk ) did a good job. i give you props man. a dergree in engineering is a good accomplishment congrats man, you should be happy.

Souljah347

we have fairly low reving engines a CAI is better for us then a SR. short rams work best on high reving engines. (this is what i was told. which makes sense to me. assuming of course you aren't already going fast enough to get rid of all the hot air from the engine)

antireversion

ding ding ding, we have a winner, what do we have for him Johnny?, absolutely nothing, but this is the reason that most CAI's are made of aluminum, for a large company that plans on doing everything in house, its much cheaper {when starting from nothing} to buy a mandrel tube bender, an assortment of dies, and a bundle of aluminum tubing than it is to purchase a screw injection type machine, pay a pattern maker to design the part, with inside and outside patterns, the process of injection molding would be very expensive {and nasty} to do in house, and there is also the marketing side of it, aluminum looks like a race car part, plastic looks like a factory part. Theoretically plastic {specifically DELRIN}would be the better material, because it doesnt transfer as much heat as aluminum, aluminum becomes the same temp as its surroundings very quickly, whether it be hot or cold, so when the engine is running and the underhood temps are high... guess what so is the aluminum, but hey if its cold out and the cars not running, that intake will be cold as ____ , and all of this would matter if the intake charge stayed in the intake tube for atleast 0.002 seconds thanx

reagulator

plus alloy doesnt rust. i think...