Headers/TPIS?
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
What type of stainless? There's lots of different grades, all at different costs and difficulty of fabrication.
Just as with steel and alum alloys, there's junk alloys and good alloys, all depends on what you're willing to pay. Generally speaking, the more magnetic and harder to weld stainless is, the crappier it is.
Just as with steel and alum alloys, there's junk alloys and good alloys, all depends on what you're willing to pay. Generally speaking, the more magnetic and harder to weld stainless is, the crappier it is.
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Stainless Works uses 304 stainless, an excellent grade. By comparison, my DRMs are 409 grade. Still functionally good but not nearly as nice.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
According to ASM Metals Handbook 9th Ed, Vol 3
Properties and Selection: Stainless Steel ...
The 400 Series of SS is ferritic and its principal alloy is Chromium.
409 is widely used for exhaust components that operate above
1,000º, particulary Cats. It is comparatively easy to weld & fabricate
and it is less expensive due to the lower costs of the alloying
materials. However, after 1,500º, 409 is increasingly susceptible to
oxidization and loses strength. In other words, 409 is a good choice
for downstream usage, but not so good for header primaries. It
does not polish up well or remain bright.
The 300 Series of SS is Austenitic and its principal alloys are
Chromium and Nickel. 304 is better than 409 from 1,500º through
1,800º but by 2,000º, 304 is in trouble, too. Still, while 304 will
fail at 2,000º, it can stand up considerably longer than 409 at 2,000º.
(In the same tests, a 309 survived at 2,000º with minor wgt change.)
In other words, 304 is ok for use for primaries on moderate-high output
normally aspirated engines but one or more other grades would be
better. Turbo or blown engines probably need more heat-resistant
grades, such as one of the Inconels.
The nickel in 304 and lower % chrome means this grade can start
out brighter and stay polished and rust/pit free longer compared
to 409.
Proper treatment after fabrication to stress relieve and anneal 304
can significantly improve its durability.
The foregoing, along with the fact that SW's primaries are 1-5/8"
are why I joined in on the GP organized recently.
Thanks for posting the GP, Corvette_Kid_NC.
.
Properties and Selection: Stainless Steel ...
The 400 Series of SS is ferritic and its principal alloy is Chromium.
409 is widely used for exhaust components that operate above
1,000º, particulary Cats. It is comparatively easy to weld & fabricate
and it is less expensive due to the lower costs of the alloying
materials. However, after 1,500º, 409 is increasingly susceptible to
oxidization and loses strength. In other words, 409 is a good choice
for downstream usage, but not so good for header primaries. It
does not polish up well or remain bright.
The 300 Series of SS is Austenitic and its principal alloys are
Chromium and Nickel. 304 is better than 409 from 1,500º through
1,800º but by 2,000º, 304 is in trouble, too. Still, while 304 will
fail at 2,000º, it can stand up considerably longer than 409 at 2,000º.
(In the same tests, a 309 survived at 2,000º with minor wgt change.)
In other words, 304 is ok for use for primaries on moderate-high output
normally aspirated engines but one or more other grades would be
better. Turbo or blown engines probably need more heat-resistant
grades, such as one of the Inconels.
The nickel in 304 and lower % chrome means this grade can start
out brighter and stay polished and rust/pit free longer compared
to 409.
Proper treatment after fabrication to stress relieve and anneal 304
can significantly improve its durability.
The foregoing, along with the fact that SW's primaries are 1-5/8"
are why I joined in on the GP organized recently.
Thanks for posting the GP, Corvette_Kid_NC.
.
Last edited by Slalom4me; Sep 1, 2005 at 02:59 AM.
