They use long ALUMINUM tubes to connect the air filter to the throttle body/intake manifold.

Aluminum is a VERY efficient conductor of heat. As such, it allows the heat from the engine compartment to warm the (otherwise "cold") air inside the aluminum intake tube as it makes it way from the air filter towards the intake manifold.

Such systems would be more efficient (and less expensive) if they were made from plastic (poor conductor of heat) and/or were insulated.

Of course, such systems wouldn't look "cool," so they're not in favor.

 

Yes, but polished aluminum has the highest reflectivity of any material.

 

That's great...for light waves.

Heat transfers right through it, though.

What material do you wrap pototoes in when you want to COOK them? Answer: "highly reflective" aluminum foil.

Please post the reference you used to support your statment that polished aluminum "has the highest reflectivity of ANY material."

Using aluminum for intake air plumbing in an engine is just plain stupid. And many of those systems use colored (anodized) aluminum. I don't see any of the manufacturers of those systems claiming any difference in performance based on the color of the aluminum tubes...Do you?

 

i think TLover was just yanking your dick when he made that comment. i think it was supposed to be funny. (which it was)

 

I don't know what her was doing.

But the fact of the matter is that a plastic and/or insulated tube would be more efficient AND cheaper to produce.

That could be wrapped in "highly reflective" tape (prior to installation) if desired. (I probably wouldn't bother.)

 

PVC is going im my Tl wait till my friends see it.LOL

 

You don't know much about cooking do you? You wrap the potato in foil so the outside does burn while the inside is raw. Therefore, REFLECTING RADIANT HEAT AWAY.

 

The entire potato COOKS, doesn't it?

And you meant to say, "So the outside doesN'T burn."

The fact remains that a plastic (vs. aluminum) tube would transfer less heat into the airstream of a "cold air" intake system.

Do you agree or disagree with that statement?

 

Yes, I agree. Plastic is preferable to raw aluminum. But the process of polishing aluminum is done to reflect radiant heat, no?

 

IF the aluminum is polished and ASSUMING that radiant heat is the main heat transfer mechanism.

A lot of those aluminum tubes are colored (via anodize).

And convection is the main type of heat transfer that would heat the aluminum tube under the hood of a car.

 

And to answer your baked pototo question:

To understand heat and cooking times:
* Convection is the transfer of heat in a fluid (liquid or gas) from a warmer area to a cooler area. This is how an normal oven works. The heat is transferred from the hot air to the cooler potato.
(All ovens are 'convection' ovens - ovens with the designation 'convection oven' simply have a fan that moves the air faster, which causes faster heat transfer - both regular and 'convection ovens cook food by convection).

* Radiant heat is heat transferred by radiation. Sunlight is a source of radiant heat. So are microwaves. So are the elements in a toaster. So are the glowing coals of a fire. Aluminum foil reflects radiant heat.

 

But CONVECTION is the main source of heat transfer under the hood of a car.

 

When then all bets are off. I thought Injen and AEM use polished aluminum -- although I've never seen one so I don't know.

 

As metals go, aluminum is a pretty poor heat conductor. It just doesn't have the molecular mass of other metals and therefore has a low specific heat. But it is still a metal, and does still conduct heat (and transfer it better than most, which is the main problem), and is therefore not ideal. One could not use "regular" plastic, aka thermoplastics, such as PVC for an intake system connected directly to the engine. It would melt or at least deform. A high temperature thermoplastic, such as ABS, could be used, but again isn't ideal. A thermoset (one that gets harder with heat) such as most silicones would be ideal. It doesn't conduct heat at all (check out those newer silicone over mitts, they're pretty damn cool, no pun). Such a material could be vaccuum metalized to appear like aluminum without the heat transfer qualities. In fact, if one is going for looks, resin impregnated carbon fiber is a thermoset-based material, so it could be used readily. Alton Brown says not to use foil when baking potatoes because they keep all the steam in and make the skin all slimy.

 

But couldn't you argue the engine itself is the radiant heat source?

 

Aluminum is a VASTLY better conductor of heat vs. cast iron, stainless steel, plastic and MANY other materials. It is universally recognized an having excellent heat conducting properties:

http://www.guardianmetal.com/aluminum.html

Virtually EVER OEM intake system (right up to the throttle body) is (cheap, injection molded) PLASTIC (usually with some rubber couplers), so I don't know what you're talking about.

How many OEM ALUMINUM air filter/intake systems have you seen?

 

I got my specific heat backwards. Switch conductivity with heat transfer and that's what I meant. It's been too long since high school chemistry.

Virtually EVER OEM intake system (right up to the throttle body) is PLASTIC, so I don't know what you're talking about. [/B][/QUOTE]

I'm sorry, but if you know your materials you will see that most OEM applications use a thermoset silicone rubber between the airbox and throttle body. The rest use an ABS like I mentioned.

 

I think you answered your own question. Plastic is cheap, which is why OEMs use it.

 

I'm sorry, but if you know your materials you will see that most OEM applications use a thermoset silicone rubber between the airbox and throttle body. The rest use an ABS like I mentioned. [/B][/QUOTE]

I guess you missed the "with rubber couplers" part in what I wrote above.

 

Aluminum outperforms the vast majority of metals in terms of thermal conductivity.

http://www.mayahtt.com/tmwiz/default.htm

 

Yeah....

But the other guy said plastic "would melt."

So you're taking my comment out of context:

 

I don't feel like reading, so what is the ideal material to use.

Isn't the comptech icebaox made out of pastic.

 

Oh. Hehe. It's an engine bay, not a pizza oven.

 

Plastic is the best that I can think of...It's a good INSULATOR, it;s light and it's cheap to make.

Relective insulator tape (available in hardware stores) could be applied on the O.D. prior to installation if desired.

That would ensure the COLDEST possible charge, which is what a good "cold air" system SHOULD do.

 

Hmmm ... but you do REALLY think there's a MEASURABLE difference in air temperature. So much so, that it would affect performance?

 

Right.

Modern cars are LOADED with plastic under the hood. Even the reservoirs for brake and clutch systems are now made from plastic.

Plastic radiator shrouds have been in use for decades and they're ATTACHED to the hot radiator!

 

Convection is the primary source of heat transfer acting on the air box/air filter plumbing.

I'm sure there is SOME radiant heat as well.

But it's a moot conversation, at least on this level, because we know that a plastic set-up (wrapped with reflective heat tape, if desired) would result in a cooler intake charge.

And a cooler intake charge = greater air density = more power.

 

I suspect that it would be minimal, but measurable.

Plastic would be less expensive and more efficient (at least in theory).

GM spent a lot of time looking @ intake manifold materials when developing the LS1. One of the main reasons they chose plastic was because it runs cooler (relative to aluminum, which continues to be the most popular choice).

 

Well smarty-pants, why don't they make blocks and heads out of plastic!!!???




J/K :lol2:

 

Seriously...

http://www.hotrod.com/techarticles/50638/

"The induction system is no less a dramatic departure, since the manifold is completely composite (plastic), insulated by a “dry” valley. One advantage to the composite intake, besides a significant weight reduction, is a cooler inlet charge due to the plastic’s superior insulating ability."

Most aftermarket LS1 manfolds are made from aluminum, but that's because aluminum is easier to machine (port) and can handle the higher pressures associated with blower applications.

 

Seriously though, I thought I read somewhere that polished aluminum is good for keeping the intake charge cool. If I find it, I'll post it.

 

It might be better than UNpolished aluminum, but it's nowhere near as good as a cheap plastic tube (wrapped in reflective aluminum tape, if you so prefer).

And as always, one has to consider the source of the "information."

Aluminum, by nature, is an excellent conductor of heat (particularly of the convection and conduction variety). All you have to do is reference any thermal conductivity table (like the one below) to see that:

http://www.mayahtt.com/tmwiz/default.htm

 

http://www.mayahtt.com/tmwiz/default.htm

6061-T6 (most common aluminum in those intake set-ups):

167 W/m-C

ABS plastic:

0.25 W/m-C

The 6061-T6 is 668 TIMES as efficient at conducting heat!!!!!!

 

Wow, someone should tell that to the window suppliers out here in Arizona. Just about every track home I've seen comes with aluminum-framed windows.

 

Yes, go to the TOV site and check the dyno test on their civic project. The fact that the radiator hose was in contact with the intake raised the temp of the air significantly.

 

Hey, I'm a journalist, I ALWAYS consider my source.

 

Why are any of you guys entertaining this benchtop racer? The CAI being made of aluminum doesn't mean crap. The air charge isn't in the 3 foot long tube long enough to pull energy from it.

Think about it, you can move your finger through a candle flame with no problems so long as you do it quickly...why? Because there is no heat transfer even though there is a heat source.

With CAI it's not about what the aluminum does, it's about what the air charge does. The air charge isn't going to pull enough energy from the aluminum to make a bit o' difference.

Move on to your next cut 'n paste article guy. Leave your benchtop and actually build a motor for yourself and you'll quickly see that most of what your read in Hot Rod and elsewhere is complete B.S.

 

Allow me to explain what I said. There are two kinds of plastic: thermoplastic and thermoset. Thermoplastic, by definition, melts with heat. Thermoset, by definition, sets with heat. Composite plastics are generally thermosets. Thus, thermoplastics are not the best materials for use in an engine bay, which does in fact work like a convection oven. They COULD melt. Also please understand that melting does not necessarily mean that the plastic turns entirely to liquid. Well, actually it already is a liquid, but that's beside the point. Thermosets on the other hand work well in high heat situations, and are therefore ideal for use in engine bay applications.

Once again, metal < thermoplastic < thermoset

http://www.rlhudson.com/tech_thermo.html

 

PS I'M AGREEING WITH YOU ALL FOR PETE'S SAKE

 

Science speaks for itself.

Aluminum is an VERY efficient conductor of heat.

period.

The fact that some track housing builder is installing cheap windows in Arizona isn't relevant to this conversation:

http://www.mayahtt.com/tmwiz/default.htm