That cutout is huge. Has 1000HP single downpipe written all over it.

 

my thoughts exactly!

 

I've got a diesel remember?

1000hp is not in the future for this truck, more like 600/1200 with a built trans turbo, ill build another quick truck later on this truck needs to be a reliable puller.

 

This is not a true statement...the higher the carbon content the higher the tensile strength..therefore 304H or just 304 for short is the stronger between
304 and 304L and since carbon content of 400 series is higher than both of those it will be stronger than 304/304L.....

On a side note in my career with deal with stainless alot..but we get dual stamped stainless 304/304L there for we are allowed to use the higher of the two tensile strengths when doing calcs.

 

Higher Tensile yield yes, but not UTS. I work in then aerospace industry, so we're constantly pushing things to the limits. Behavior in the plastic region is of a concern to us. Most fields just use the Tensile yield for design, so I think that's where the confusion comes in. Just because it's stronger doesn't mean it's better though. Stronger means its harder and more brittle, and in Cody's case of 409 vs. 304, more difficult to weld.

.....................304.......304L.....409
Tensile Yield:..31200...30500...34800
UTS..............73200...81800...65300

So why are you allowed to use the higher of the two values when doing calcs? I would think you would need to use the lower of the two given the probable failure mode. In other words, if it's going to fail, its way more likely that'll be the weaker of the two materials.

 

I dont see the argument here.
Yes there are physical and chemical properties that are different between the two grades.
Yes one will color differently which would make it a better candidate for a cosmetic application.
Both grades 408 and 304 have been used successfully in the exhaust market for years so either will do the job just fine without ANY issues.
If you want the nice coloring effects that most admire about stainless go with the 304.

You guys are taking the choices here to the extreme, none of you guys must deal with budgets lol.
Id hate to see what type of water pipe you guys would run at your house. (schedule 40 3"? )

What im getting at here is Codys application will not see the FP or failure point of the metal grades mentioned, therefore its pointless to justify this grade over another based upon Aerospace standards.

Hell, if appearance wasn't an issue in this case id recommend plain old mild steel.
Cheap and would work great, yes it rust but then again it would take XX amount of years before it would be an issue.

 

I deal with process equipment and pressure vessels...We base all of our cals in whats allowed by Section VIII snd VIIII of the code..and according to that we are alllowed to.. the ASME works all those details out so we dont have to...and besides that calcs like thickness when done are done at a design pressure and temp, because temp obviously plays a role in this, which is hgiher than actual operating pressure/temp so your good there..

 

I too wish to eventually add a cutout to my Corsa. I want the same material they used. But, I don't want to cut my pipe between Cat & Muff. Therefore that'll be a new piece of S/S w/ cutout added. I'll be better informed on if it's cost prohibitive or if I'll be forced to cut due to $.

IIRC, I think the 300 seies will discolor the least, but I'm no metallurgist. And it's been awhile since I read on grades, so forgive my memory if I'm full of It's not something I need to deal w/ daily, rest assured I'll research when I'm ready.

I'm very picky too, & was told so by someone on ZR1 build team @ Woodward yesterday. Unlike u, I live in Mich. (home of rain, snow & salt)!!! I have no prob thus far will my Corsa system's appearance.

How did u get Corsa to do up a turboback setup? U also have different requirement(s) than me due to all that heat.

When I read 1st post or so, I wanted to say call Corsa. They use all the same higrade even on the hangers (Borla uses diff. grade on hangers). Since u have a Corsa turboback back, I think your answer will be to just call them. Or SW. Burns Stainless or a metallurgy book might also provide insight. Please post the route u take! PICS too!

IIRC, ditto on higher nickel & chromium. Carbon & price too. But gorilla knows on rod choice, not me. Again, dealin w/ something daily allows 1 to be better versed. Here to learn; now if I retain it.

Copper SCH40 maybe?

I think it's the consistent appearance Cody is going for as I saw his earlier posts. I don't think he'll hammer the **** outta it to see if it's tough or not.

 

Corrosion resistance between grades of 300 series SS will be negligable for your application, discoloration is related to the grade and the thickness of the tubing used as well as other things like actual flow at bends causing hot spots.
Heat will affect the material's growth and twist rates depending on the design of the part, where heat spots are more prevalnt, where welds are placed, and tubing thickness will also have an affect too.
For a cut out it's pretty straight forward and the heat will not be that intense as to cause real issues.

 

Ended up ordering this
http://store.summitracing.com/partde...5&autoview=sku
Ill update late on how it turns out discoloration and distortion wise. If it discolors too bad Ill get it ceramic coated. Should sound pretty good with an open down pipe