Air Intakes: SS vs Aluminum

[Kreator]

Ok so all these companies make these expensive intakes (injen, aem) from aluminum alloy. Yet, stainless steel is harder to warm up, and much easier to bend and the material is much cheaper as well.

So the question is, why all the good performance companies make intakes out of aluminum? right now i'm comin up with just 2 differences:

Stainless steel - harder to warm up(+)/heavier than alum(-)
Aluminum - very light(+)/heates up faster(-)

So anyone can tell me what i'm missing? cuz i don't really major difference. And ofcourse knowing why people would rather buy aluminum intake vs ss also helps <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/thumbs-up.gif" border="0" valign="absmiddle" alt=':thumbsup:'>

[Jeff240sx]

I think you're mistaken here...
Stainless steel is harder to warm up because it absorbs heat. &nbsp;And keeps it, and if it's hard to warm up, it's hard to get cold. &nbsp;
This leads to:
Aluminum is best because it is a great conductor. &nbsp;The pipe itself gets hot because that's what a diffuser does. &nbsp;It takes heat from air fast, and loses the heat fast. &nbsp;This is why not only are intakes made from aluminum, but intercoolers are also. &nbsp;You also hit up the 1/3 lighter metal.
-Jeff

[Kreator]

But once both intakes warm up, neither one gets cold, cuz the air inside is always hot. I mean the only time they are given a chance to loose hit is when u stopped moving and turned the engine off

P.S. I thought ss was used for intercooler piping...

[uiuc240]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Kreator @ Sep. 24 2002,10:07)</td></tr><tr><td id="QUOTE">But once both intakes warm up, neither one gets cold, cuz the air inside is always hot. I mean the only time they are given a chance to loose hit is when u stopped moving and turned the engine off

P.S. I thought ss was used for intercooler piping...</td></tr></table><span id='postcolor'>
not entirely true. &nbsp;the air moving through it gets cooled down much better with aluminum than with steel. &nbsp;and the only IC pipes that are steel are the custom fabbed ones because it's cheaper and easier to get than aluminum. &nbsp;easier to weld too. &nbsp;you have to "braze" aluminum since a MIG/TIG welder gets too hot and just burns through it.

Eric

[Jeff240sx]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (uiuc240 @ Sep. 25 2002,1:19)</td></tr><tr><td id="QUOTE"> easier to weld too. you have to "braze" aluminum since a MIG/TIG welder gets too hot and just burns through it.

Eric</td></tr></table><span id='postcolor'>
You can TIG weld aluminum. &nbsp;The problem is that Argon gas is expensive, as well as the whole TIG setup is friggin expensive. &nbsp;
-Jeff

[mrdirty]

I doubt you're ever going to see a real differerence between the two but:
-if u look at it from a thermodynamic point of view, the aluminum will heat up faster and allow more heat to transit into the intake stream for a given amount of time. What you're really doing is setting up a temp gradient in the wall of the intake tube, the air coming in will remove some heat because it is cooler which causes heat to move from the outside of the tube to the innner wall; aluminum allows this to happen quicker than SS.
-unless you are getting air from a source cooler than the engine bay it doesn't matter, it's all the same temp under there anyway.
-if u really care about getting a cooler charge, wrap your intake.

[luke91]

"you have to "braze" aluminum since a MIG/TIG welder gets too hot and just burns through it."

This is not true. You CAN weld aluminum with a MIG welder. It really isn't that hard, either. All you need is aluminum wire, and straight Argon gas. Neither of which is expensive.

Anyway, the difference in power being produced by an intake with aluminum piping as opposed to steel is so small it's irrelevent. Unless you're running The 24 Hours of LeMans.

--luke</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE"></td></tr></table><span id='postcolor'>

[luke91]

I give up!!!!

I don't know how to use the "Quote" box.

--luke

[ridebmx]

this is sort of off the topic, according to what the 240sx computer reads while driving IAT is the same as outside air tempature, atleast going down the highway, if you let your car sit there and idle and watch the OBD II diagnostic screen the tempature goes up quiet a bit, so my question is how are the more expensive intakes supposed to help as in cold air extentions and what not, the only way i can see is maybe alittle better flow.....

[Kreator]

Ok, so from what i'm understanding, the cooling efficiency is minimal, yet the pricing is pretty tough. Yet most performance companies decide to make aluminum intakes and sell em for alot while ss would prove to be much cheaper.... anyone can answer why?

[Kreator]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (ridebmx @ Sep. 25 2002,11:27)</td></tr><tr><td id="QUOTE">this is sort of off the topic, according to what the 240sx computer reads while driving IAT is the same as outside air tempature, atleast going down the highway, if you let your car sit there and idle and watch the OBD II diagnostic screen the tempature goes up quiet a bit, so my question is how are the more expensive intakes supposed to help as in cold air extentions and what not, the only way i can see is maybe alittle better flow.....</td></tr></table><span id='postcolor'>
I'm guessing when u are going full throttle, the air comes through very quickly, therefore it doesn't have enough time to get warm because of the piping, so u actually do get some cooling from it....

[misnomer]

A lot of this also depends on airflow past the intake pipe, if you have some venting up there, aluminum will stay cooler (why else do they make heat sinks out of aluminum?). If the air is stagnant outside the pipe, it doens't matter 'cause there's nowhere for the hot air to go. This is speculation, but I'd expect aluminum to pass more heat to the air moving inside the pipe. Stainless steel has a higher specific heat. Takes longer to warm up and cool off, but won't pass heat to the air in the middle as much.

[sykikchimp]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (misnomer @ Sep. 27 2002,02:30)</td></tr><tr><td id="QUOTE">A lot of this also depends on airflow past the intake pipe, if you have some venting up there, aluminum will stay cooler (why else do they make heat sinks out of aluminum?). If the air is stagnant outside the pipe, it doens't matter 'cause there's nowhere for the hot air to go. This is speculation, but I'd expect aluminum to pass more heat to the air moving inside the pipe. Stainless steel has a higher specific heat. Takes longer to warm up and cool off, but won't pass heat to the air in the middle as much.</td></tr></table><span id='postcolor'>
Aluminum is used in heat sinks because it Draws heat in and away from the source of the heat very quickly, and radiates that heat equaly as fast. &nbsp;what you really need to know is how much energy it takes to heat Air. &nbsp;And the volume and velocity the air is moving through the intake piping. &nbsp;If aluminum is busy gathering heat, and radiating it fast enough it will only moderately warm the fast moving air in the intake. &nbsp;Now if you have steel, which would more than lickly get much hotter than the aluminum pipe would, it would warm the air quite a bit more. &nbsp;But counterpoint, if it doesn't radiate as fast, would it really heat the air any more than aluminum due to the velociy the air is moving? &nbsp;

I am assuming air gets hotter faster if it is going through a pipe that is hotter.. &nbsp;probably exponentially so. &nbsp;If this is true, then the warm Alum. pipe would creat much lower Air temps then the somewhat hotter Steal pipe.

Just an idea....