intercooler pipework: alloy,stainless or mild?

[StuC]

Hey all,
I'm gonna have a crack at making up some pipes for my new cooler setup. It did have alloy pipework in there but as im downsizing from 3" to 2.25" i need to start from scratch. So, main question is what is the best material to go for as far as thermal properties go? Stainless? Alloy? Mild im guessing will be rather crap but easy on the wallet. I will be getting them thermal coated as well, unless someone here can provide ample argument not to, in which case i will be painting them black.....

Cheers,
Stu

[blakeg]

my thoughts would be alloy would be the best for dissapating heat quickly, also it would be less likly to corrode, i wouldnt want mild steel, i would be afraid of rust forming in it. plus its heavy and would hold heat.

i have seen setups that are hotside in stainless and alloy for cold,

alloy ftw.

[StuC]

thats what i thought. i was looking at a 'cooler pipe package' off ebay. Basically pick any 6 types of pipes, joiners and clamps for $120 bux. Was alloy but im assuming it will be of the low grade, thin variety. Chep option for me though and somewhere to start/stuff up considering i'll be doing it in 3 places. Cutting at home with a mitre table and hacksaw, marking up with texta, tacking together at work, double cheking and then welding in full back at work.

[danielk]

Yeah it's the cheap stuff. Welding guru at work made mine look fantastic though (my old starlet) just using the bends you get in that kit. Definately doable and by far the lighter option.

[Draven]

alloy. no real benefit of going anything else, a long as you/someone you know can weld it for you. Don't need aero-grade alloy for ic piping, just something that won't corrode and can handle a bit of flex. lighter too.

For the bees dick of difference it will make, you should leave the hot side uncoated and the cold side thermal coated (tho honestly you won't tell the difference, so do something that looks nice)

[StuC]

Hot side is being retained from the last setup and is a high grade, thick walled alloy. If thermal coating wont really do anything rattle can black will do me fine. Crinklecoat cooler piping a little too much you think?

[oldcorollas]

alloy has fastest thermal conductivity, then mild, then stainless as slowest.

it depends if you are trying to let heat out, or prevent heat getting in?

if the air going through pipe (ie hotside) is hotter than engine bay (on boost), you want heat getting out = uncoated alloy.
but when colder (not on boost) you want to prevent heat getting in (heat soak) = coated alloy (or coated stainless)
but thats a moot point really since the cooling effects will be minimal compared to an IC anyway....

in the end, as draven said, get stuff that you can get welded.

no need for coating UNLESS the intake pipes are close to the exhaust/turbines, in which case you coat to prevent heat getting in, but a physical shield (ACL stuff) is better than coating for radiation heat..

so it7s a layout thing relative to exhaust, rather than an air going through pipes thing...

mild sucks cos eventually it will corrode unless coated, and no weight advantage.

[Supra967]

You'd need to own the car a long time for the inside of a relatively sealed mild steel pipe to corrode. Painted outside would last a long time too. The mild bends i got for exhuast were pretty poor quality though. Also, as rolla was saying, heat transfer is two stage, storage and transfer. You do not want to transfering heat through the cold side, so i'd be going for storage capacity (coated/steel/heat shield etc) if you're worried about heat.

Al for weight wins out though i reckon

[JDM hachi]

Surely, even in the healthiest of engines, a tiny bit of oil will coat the inside of any intercooler piping? So mild steel will be fine, and shouldn't corrode, isn't that what comes from the factory in most cases?

matty.

[oldcorollas]

if one has the cam cover breather directed to the airbox/just after they will. no problem
if directed to catch-can and vented, a bit less likely (for cold side).
still should be fine, but will corrode eventually. depends which steel you get, and where you live.

factory cold side = plastic?
factory hot side = IC then alloy plenum (in mine), or cast alloy, or painted pressed steel (clam) pipe?

[fixeruperer]

stainless, coz the weld heat marks look cool
some Ti would be even nicer

[JustenGT8]

Mild intake piping will rust, seen it a dozen times.

I went with stainless as there were no decent mandrel aluminium bends readily available at the time. I have the al bends now and one day will redo all the piping. No issues with the stainless other than it's a bit weighty...i have more piping than a turbo 4 though and big dia as well. 6 of one really Stu for you.

[Supra967]

I had a non turbo cold air intake in mild, filter down in the rain (cheapo filter mesh rusted) but piping still shiney on the inside after a couple of years. They'll surface rust on the outside if you don't paint it, but it will do nothing more than look ghetto spec I've seen old m/s piping that surface rusted on the outside and the engine bay looked like vomit.

[YGO 08]

my first turbo car had stainless and it kept the heat in a fair bit. since then i tryed alloy and would never look back. still retains abit of heat but nothing like stainless and when im at the track it cools really quick between runs were the stainless didnt.

[alexlegault]

im not sure but i think aluminum absorbs heat less than steel/.