aluminium exhaust, a good idea?

[oldcorollas]

galvanic between the steel and the aluminium?
i can't remember exactly what come sout of an exhaust, bu tthere will be some sulfur and manganese and crap in there. the water than condenses in there will probably be acidic also, but i 'm not sure what effect that would have (been too long sinc ei studied this stuff )
i would guess the NOx will form some nitric acid, and there may be other acids also (not many chlorides you would hope)

the other thing is that exhaust is often a very low oxygen environment, but i am not sure it would be reducing enough to remove the oxide...

hmm, someone stick some alloy into their exhaust (in teh middle) and see what happens?

edit, aluminium boat exhaust manifolds for V8's? water cooled no? but they have zinc anode (due to water... not the exhaust)
http://www.boatstoreonline.com/glmexhaust.html
http://www.boatstoreonline.com/images/c6_12_1_.jpg

[oldcorollas]

this is one benefit

[Lambolica]

I was thinking more betwwen the Al and any Stainless bolts that may be used to hold the shebang together. However thinking about it the connection would be out of harms way so to speak, I'd say the exhaust would die of natural causes than from galvanic issues.

Cheers
Simon

[oldcorollas]

stainless and alloy is usually a no-no....

this paper might help?
http://cat.inist.fr/?aModele=afficheN&cpsidt=1658673
Ornektekin, Sermin. Effect of exhaust gas on corrosion of metals. International Journal of Environmental Studies (1998), 55(3), 199-210. CODEN: IJEVAW ISSN:0020-7233. CAN 129:319461 AN 1998:721769 CAPLUS
i don't have online access

[Draven]

Oc: what makes you think that if *you* don't have access that any of us would?

edit: just check the MQ database and no such luck

[oldcorollas]

ya never know. i tried SciFinderScholar and ScienceDirect, but no online access for me.

it doesn7t seem to talk abotu strength/vibration issues, just the corrosion side of it.

[Draven]

yeah, sciencedirect let me down too I tend more toward human sciences rather than "real" sciences

[YGT04A]

I have got the full copy in a PDF of you would like to read it

the artical was actualy published in an environmantal science journal so I was able to get a copy

[oldcorollas]

any good?.

[allencr]

I think this is about the only thing you'll find with an alum. exhaust manifold, air cooled, and those fins might really be a necessity!



Most of us have see dull red or glowing red cast iron & steel exhausts, so what's that temp compared to aluminum's puddle point.

[oldcorollas]

manifolds/headers/turbos yes
dull red is 500ish? i forget exactly, but enough to make alloy all gooey

but if your exhaust is still red hot halfway down the car, you are doing something wrong no? not that there is much weight saving vs cost for the long straight pipe down middle of car... but mufflers weigh a bit...

hmm,
http://www.hindle.com/products-traditional.html

seems only race bikes and boats (volvo etc?) use them commonly
but boats are water cooled

edit: but did find this in my searches
http://www.alibaba.com/product-gs/52...or_TOYOTA.html

[wombat]

[QUOTE=oldcorollas]
but if your exhaust is still red hot halfway down the car, you are doing something wrong no? QUOTE]

I wouldn't say that. In dyne testing we have a bigger exhaust than standard, which flows alot better, we control backpressure with a valve at the end of the exhaust. Anyway point it we would easiler get the manifold glowing red/orange and also a good almost 2 meters of the exhaust too. Obviously this is at sustained peak revs tough,a good 7,200 from a V6 for say 2 mins. The colour does stay for the majority of the test though, just not as intense.

little side note that I find interesting is when we test some of the v6 turbo you can literally see though the exhaust side of the Turbos. now that was really cool the first time I saw that!

[YGT04A]

any good?.

I have not had a chance to read it yet I will let you know later today

[amichie]

Ideally the exhaust headers should be made from a material that is a poor conductor to keep the heat in and exhaust velocity high. This wouild be a good reason to choose Stainless over Aluminium.

[MR22ZZ]

Oc: what makes you think that if *you* don't have access that any of us would?

edit: just check the MQ database and no such luck

I have access