Exhaust material, GTI owners, your opinions?

[kaanage]

I'd love to see the price of a titanium exhaust!!!

For the non-technically minded, aluminized steel is like galvanising except for using aluminum rather than zinc as the coating (or alcad aluminum with mild steel being covered by raw aluminum instead of the body metal being an alloyed aluminum) - it's nothing like an alloy.

The fatigue properties of stainless may be better up near the turbo outlet where the operating temperature is high (this is where titanium really shines) but welds can be brittle and crack from vibration (although the welds will be as corrosion resistant as the rest of the sheet while this will not be the case with an aluminized steel fabrication). The other advantage of stainless steel is that scratches won't affect the corrosion resistance while aluminized steel will rust if the the scratch is deep enough to go through the aluminum cladding (something for the slammed crowd to consider).

Tensile strength of mild/aluminized vs stainless steel isn't very different (assuming both have been cold worked to a similar degree) but mild/aluminized steel is much easier to work with.

stupid americans, can't even correctly spell an element

What's wrong? We use the terms "sway bars" and "shock absorbers" so why not aluminum (and gasoline and tires)

[gavs]

What's wrong? We use the terms "sway bars" and "shock absorbers" so why not aluminum (and gasoline and tires)

Yes, but they are technical descriptions, not an atomic element that can only be that specific element, rumour has it according to my old chemisty lecturer that the reason they spell it differently is because it was so hard for them to proncounce that when someone said "Aluminum", they could not relate it to the true "Aluminium" spelling. Don't know how true that was, but I like it, it sounds feasible enough, especially considering whatching a doco in Queen last night, an ex journo from Rolling Stone said that Queen wasn't overley successful with their album "Jazz" in the US because the public couldn't understand that just because an album is called Jaz, there is no Jazz music on it, or the fact a band with 4 men could be called "Queen"

Technically it's classified by manufacturers as an alloyed material due to the aluminium having to be fused into the steel somewhat as the aluminium doesn't bond very well to the steel, unlike Zinc plating, e-coat, nitriding etc. Splitting hairs here though

Guy, I think you have had your question answered

[kaanage]

Eutectic mixture at the interface?

But it was the original name given to the element and it's shorter and we love US terminology here (add color to the list above)
World Wide Words: Aluminium versus aluminum

[Guy_H]

The Americans can't pronounce "Soldering" either

[RoknRob]

So will the system be clad inside AND out with alumin(i)um?

We may not get 3 months of harsh exposure to salt, gavs, but wouldn't continuous exposure at low levels add up? Just playing Devil's Advocate - is there a definitive study on the subject?

BTW, count me in as someone who is happy to teach his kids that both spellings are correct, depending on where you are. Just like I am happy to be called Roberto in Spain. It can be chips or it can be fries. It can be tomato or it can be tomato.

Can't we all just get along?

[kaanage]

It'd be clad on both sides of the sheet metal. In our conditions, it'd last just fine unless you had a slammed setup so the aluminum layer got scraped through. The welds aren't fully corrosion proof but it would most likely take a decade for them to become an issue.

[gavs]

Yeah, exactly. My golf was over 10 years old when I sold it and the exhaust still looked brand new after being washed, only corrosion was on some of the welds but not heaps and my car came from far north Queensland

[Guy_H]

Remember, the stock system is "Aluminised", pull one off a 12 year old Golf 4 GTI & they generally have no signs of corrosion.

Our new manufacturer does a lot of 4WD systems, and they get very good service life out of them, even when driven on the beach!

[Greg Roles]

42DD have an extremely low problem rate using alum-mild steel on all their systems. I am yet to have a single problem, but my numbers are nothing like yours Guy. That said the lowest hanging bits are indeed stainless magnaflows mufflers and resonators, I would assume any local pipe would have stainless muffs? This is typically where any acidic condensation seems to rust out old steel systems first...and where the slammed cru would be sparking first.

I think steel is fine unless you intend to keep the car for longer than 10 years, or drive over salty ice!

Also, even in massive 2mm thick 14 gauge wall, the 42 systems are lighter than OEM, but I suspect that's a muffler difference just quietly!

My vote is a somewhat biased mild steel!

[h100vw]

Stainless was all the rage in the UK but Standard VAG systems would last 10 years even with the salt in winter. I'd be cool with a combo of mild and stainless in an Australian system.

Gavin