I remember reading (lost article) the ups and downs of different metals/materials to use on turbo applications for exhaust manis.......isn't Iron one of the better for heat energy retention?

Just wondering what is the overall better material to have the manifold made of and why?

 

Gold.... for bling factor

Just don't start the car hehe.

 

ROFL......

 

Cast iron is very good. Amazingly enough, stainless is not that great because of the way it expands with heat. But it lasts forever and looks neat-o

 

Forged stainless is probably best overall for its durability. It can also be polished to that high gloss mirror shine for that extra *bling-bling* effect! LOL

 

Yeah, I would wrap whatever I got so "bling" isn't a factor.

 

Haha, I am messin with ya man. I think I need heat wrap on my **** too, everything is so freaking hot under the hood.

 

Summit racing.........like 50 dollars for 50 feet.

 

Sounds good, I will have to flip out my CC again hehe. Thanks for the info.

 

 

I can't find that heat wrap stuff anywhere! I've looked all over Summit and for the life of me I can't find it anywhere, and I need to wrap my A/C lines up soon!

 

A few related questions:

I read on a post on here a while back that wrapping the mani can cause it to warp?
Isnt stainless more prone to cracking?
What temp does the turbine side of the housing get to?
Is wrapping that a bad idea, should one just wrap the compressor side and not the turbine side?


[Modified by CustomCockpits, 6:04 PM 6/20/2002]

 

go to "browse catalog"
click "exhaust"
click "header bolts and wrap"

 

yes, they can crack and rust more with wrapping. I researched this heavily a few months ago. You are better off leaving the exhaust components and turbo free to air and just insulate everything else near it!

 

I thin kthe best material to use is...........................


INCONEL!!!!

 

I'm really digging this cast stainless stuff. Durable, and nice and shiny. But, should it ever crack, just reweld it...and it can be rewelded again and again! Also lighter than iron by a lot.

 

.stainless, even basic grades have much better thermal expansion characteristics than carbon(cast iron) steels. the problem you may speak of is poor quality offshore material making its way into manifolds, if you select a grade properly it will not expand, or conversly not expang with the ports of the aluminum head at the same rate.
the best and most basic heat resisting grade is 314, 309, 310, 330Cb, then the Nickel alloys start to enter the picture, due to their lack of availability and high price I wont mention any

 

lighter only because less material can be used - strength to weight ratio. Stainless is slightly denser than carbon steel - 7.85kg/dm3 vs 7.90kg/dm3 on average.

 

Inconel (sp?)

 

Inconel is VERY expensive, but is great for this type of usage.

I think the best all around just for function and price is cast iron...Lots of people don't realize that you actually WANT your exhaust manifold to keep the heat INSIDE, because hot air expands and keeps expanding, therefore it pushes the turbine faster and faster...not sure if I can explain that better in my head, but in my head it makes sense Its something along those lines.

 

I was thinking Cast iron as well.....with header wrap

 

Here's a good article on materials for exhaust manifold applications: http://www.burnsstainless.com/TechAr...s_article.html

Also look at the "Material Properties" table at the bottom of the page.

Personally, I will be using 321 stainless for my manifold.

-Seth


[Modified by TheShocker, 12:45 PM 6/21/2002]

 

from a pure materials standpoint:

Inconel is the best material, bar none. Expect to pay about $3-4k for a good inconel manifold (thats what an aircraft inconel manifold goes for, usually more with the cert.)

Second best is 347 stainless, a slightly less expensive alternative to inconel.

Third best is 321 Stainless, a light less expensive alternative to 347.

4th is 316

5th is 304

then mild, and cast is at the bottom.

What people need to realize is that the cast manifolds coming with most kits are *sand castings* there are many different kinds of castings and sand castings are the most porous, weakest and most likely to crack castings of all.

Also in my humble opinion, the most important thing in exhaust manifold strength comes from wall thickness. Read corky bells book, Hugh MacInnes or really any SAE paper on turbocharger manifolding. Wall thickness = strength. If anyone remember a post i had a while ago comparing the forged 8 gauge material we use (maxrev and full-race) compared to the 304 that say revhard or kiwi uses, you can clearly see that the 8 gauges is 7-8 times thicker. This thickness allows for a stronger weld joint, less movement and an overall better insulator. I would rather have the thick 304 than thinwall 321 any day on any application.

The reason most comapnies do not use these better materials and thicker materials is that they both cost much more than the thin stuff (on the order of 5 times more) and it take a very very long time to cut through it, even on the most powerful of bandsaws. This is just from my point of view and from the experience i have had using and making a number of manifolds.

BTW the full-race manifolds are made from 316/316L from this point on.



[Modified by FFgeoff, 1:58 PM 6/21/2002]