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Are factory exhausts for 97 4.6 stainless of aluminized steel? I have to weld in new cats, just wondering what material I'm dealing with.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Mine were definitely aluminized... ;)
 

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My 96 is definitely stainless, it would have rotted off by now if it was not.
 

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Stainless (generally) will be nonmagnetic.

Try sticking a magnet to it. If the magnet barely sticks it's stainless. If the magnet adheres strongly it's aluminized steel.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Well mine was certainly quite rusty when I took it off, so... :zdunno:
 

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Quick someone grab a PMI gun.

And a copy of Mechanical Engineer's Reference Book.
LOL :tongue:

I consulted one of then engineers and one of the welders that I'm working with before posting the reply above ... You know what I do, and we were all in agreement.
 

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Stainless steel CAN rust. Some faster than others.

Stainless just doesn't rust as fast as aluminized or cold-roll steel.

RwP
 

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I believe mine is stainless as well. It's in pretty good shape and is all original which is 288K miles worth. Other parts of the car aren't as lucky
 

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As it's already been said the factory exhaust is stainless..A low grade stainless probably a 409 type stainless, but stainless nonetheless..

I have very few exhaust mods..

A set of High Flow Cats with the 3rd cat, and resonator eliminated with a 3" y-pipe..Then back to the stock exhaust right before the fuel tank..

The only rust on my factory exhaust is the front section that was modified, and that's only surface rust..

Someone should try polishing their factory exhaust just to see how much of a shine it will hold..Since it is stainless after all.. :D

It only makes sense if/when I upgrade my entire exhaust I should use stainless instead of the cheap aluminized tubing..

There's no reason to downgrade in quality if the factory used stainless..






Rayo..
 

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As it's already been said the factory exhaust is stainless..A low grade stainless probably a 304 type stainless, but stainless nonetheless..

...

There's no reason to downgrade in quality if the factory used stainless..

Rayo..
Type 304 is not a low grade stainless; type 409 is the lower grade and most likely the grade of stainless used for the exhaust from the factory. See below for why.

My magnaflow muffler is covered in surface rust, which is 409 stainless steel, so...

someone got ripped off :tongue:
From Wiki:

"Type 409—cheapest type; used for automobile exhausts; ferritic (iron/chromium only)."

From BORLA:

"... Also, the inferior [409] grade of stainless is the only cheap material that will last through the factory warranty period."

BORLA uses T-304 series austenitic stainless; the classic 18/8 (18% chromium, 8% nickel) stainless steel.

304 is also non-magnetic due to the higher nickle content; 8 to 10% nickle for type 304 vs only .5% for type 409.

If it sounds like I'm promoting BORLA well ... yea ... I am a fan of theirs. :tongue:

http://www.borla.com/support/faqs/what_makes_an_austenitic_steel_the_best_choice_for_an_exhaust_upgrade

http://www.autoanything.com/exhaust-mufflers/flowmaster-vs-borla-exhaust-performance-and-sounds.aspx

So the SS on boats is going to corrode.
It all depends on the type of stainless; there are about 30 different types ranging from 100 series to 600 series ...

http://en.wikipedia.org/wiki/SAE_steel_grades#Stainless_steel

Also see: https://www.dieselnet.com/tech/diesel_exh_mat.php There's a good discussion of stainless in automotive exhaust systems at this link.

It's not just salt that will cause corrosion in stainless:

"Also, some commonly used stainless steels, such as type 304, have been found to corrode after exposure to urea decomposition products in high temperature environments." This problem is mostly related to diesel engines.

"Some of the stainless steel car exhaust systems available in the market these days are built of aircraft-quality T-304. It is true stainless inside and out, not aluminum, not mild steel, not coated aluminum, not just enveloped with stainless on the outside for show.

Car exhaust coatings extend the life of mild steel however; coatings suffer at the weld points. Compared to aluminized steel, 100 percent [stainless] steel has the highest chromium content, making it the most resistant to corrosion. Moreover, it is the most reliable material for a long-lasting car exhaust system."

http://www.streetdirectory.com/travel_guide/54871/car_parts/why_choose_stainless_steel_on_car_exhaust.html

Got GOOGLE? :tongue:
 

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Thank You Dr.Wikipedia.. :zbash:

Yeah I had that backwards..The 304 is the better of the two between the 304 and 409 stainless material..






Rayo..
 

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I just replaced the exhaust on my '92 LX. It was kinda sad because the old exhaust came out entirely intact as if you could install it again and go for many miles. I thought I could hear a small leak but I replaced mostly to get all I could out of my engine without changing heads. I've read my 1992 is stainless, or was, dual 2.5" no cats True bendz aluminized now. Might have to park it for the winter to save the most valuable parts now.
 
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