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The Essential Exhaust Choice: Aluminized or Stainless?

Posted by Jason on 10/14/2011 to Informative Articles

One of the most common questions that we receive from our customers here at Stage 3 Motorsports, is THE exhaust question to end all exhaust questions: should I get stainless steel or aluminized exhaust kits? Our answer is always yes. The real determining factor for the Great Exhaust Decision is the climate for where you live. For those of us who enjoy the dry, arid wastes of the American Southwest, Australia and Saharan Africa, aluminized exhaust systems are the better choice given their lower prices and the absence of humidity, snow and salted winter roads. For the rest of the world, we strongly recommend spending the extra money for a full stainless exhaust system that will actually save you a boatload of money in the long run.

The real difference between two lay in their very distinct manufacturing processes. Aluminized steel involves taking some sort of standard-grade steel and using a hot-dip galvanizing process to coat the unfinished steel in a layer of tough, corrosion-resistant aluminum-silicon alloy. Most hot-dip processes are accomplished by bathing the steel in a molten bath of alloyed metals that can reach temperatures of up to 860 degrees Fahrenheit. The aluminum alloy forms a tight chemical bond with the steel that keeps out moisture and other corrosive elements while still dissipating more heat than cold-rolled or other types of galvanized steel. The main benefit of aluminized steel versus stainless is its light weight, low cost and are extremely workability.

Stainless steel on the other hand, are purpose-built steel grades that have been alloyed with chromium, nickel and/or manganese to create a completely corrosion-resistant material from the ground up. Several different grades of stainless steel exist, with either 304 or 409 stainless steel being the most common for exhaust systems. 304 steel is part of the austenitic class of stainless grades and are identified by having at least a 16 percent chromium content with trace amounts of nickel and manganese and have extremely low carbon counts to reduce or eliminate corrosion issues at weld points. 409 stainless steel is a ferritic class steel that contains more carbon, but less chromium and almost no nickel that makes 409 systems more susceptible to corrosion; but stronger, more heat resistant and are easier to machine than other grades. Both 304 and 409 steel are more corrosion-resistant than aluminized products, but it comes at a price tag that may be several hundred dollars more than similar aluminized systems.

Neither type of exhaust material has a definitive performance advantage, and the only consideration to which type of system to use should be the climate in your region and your specific application. Your driving habits are just as important as your weather when it comes to exhausts. One of our customers from New England used his Mustang as a daily car for his commute all year round and managed to completely rust out his aluminzed exhaust in only TWO years. However, customers from a similar climate zone that keep their cars in the garage and only use them at the track can keep an aluminzed exhaust looking flawless for the life of the vehicle. In the end, those who like snow, blizzards, Nor'Easters and the type of humidity that feels like six tons of bricks balanced on your shoulders should probably stick with stainless steel. For people like us at Stage 3, who bask in the Phoenix sun on regular basis, wear jackets at 75 degrees Fahrenheit and have to look up "rain" in the dictionary, aluminized exhausts will save money while being perfectly viable for everyday use.

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1 Comments

Paul

Date 4/9/2018
Reply

I don't follow this piece at all. I've been in Cadillacs for 45 years. Back in the day we used ordinary steel (usually Walker) exhaust systems that fit properly and lasted for years in a county that had terrible winters AND the car stood outside. They left the factory surely with mild steel exhausts? The entire article is also based upon corrosion? What about noise? It's a simple fact that stainless steel exhausts are more noisy, the last guy I knew who had one, cost a fortune, the car lost it's classic baritone sound, it sounded tinny? Years ago when people like Rolls-Royce were talking about stainless exhausts Cadillac did a lot of work on it, mild steel were so much quieter. The centre pipes (on '70's Cadillacs) were also double skinned and standing next to them running, now today, way quieter than my '79 RR and that has a factory $2000 system on it.

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