Post #4334 in this thread, and that's what you put up as your first post?

 

Very pretty! Let me guess, titanium?

 

Inconel

 

Inconel is a broad name for a variety of alloys. Could you be more specific?

 

Do you have all the specs for that car listed out somewhere? Clutch, turbine housing a/r, drivetrain mods, stuff like that. What clutch do you use LOL?

 

Inconel is a brand name that's similar to high nickel content stainless steel.
For those who like to read until they weep, here ya go;
http://www.matweb.com/search/QuickTe...chText=inconel
have fun!

 

Even better! I didn't know inconel was that light. Must've cost you a pretty penny.

 

They're not lightweight materials, at least not in the sense of aluminum or titanium alloys. They have about the same density as steels. However, some Inconels are very strong and could therefore be made into ultrathin wall tubing that can be lighter than 304SS tubing. More than likely its Inconel 625 as that seems to be the Inconel of choice for exhaust systems. It comes in a variety of heat treat conditions, some of which produce very high strength but also reduced formability. No matter what, it was definitely expensive.

 

 

would Ti be better/cheaper for dp?

 

thing about inconell is its strength and corrosion resistance AT ELEVATED TEMPS... that is why NA exhaust manifolds out of that stuff use something like 0.7 mm wall thickness..

biggest problem with DP and exhausts in general is that the stuff we can buy commercially is relatively thick walled for our purpose... the exhaust could comfortably be made from 1 mm walled 308 SS but instead it is usually 1.5 mm or so.. hence the weight..

as for TI.. it doesnt like high temps so DP is fine but primary manifold NO, although some companies such as Akrapovic do use it in that application, but for cars with lots of airflow over the primary manifold (porsche turbo) and they use a combo of tubing and cast TI parts which allows them to change material thickness at will..

 

Correct, it is Inconel 625. Thin wall for the weight savings.

Inconel would be better than Ti for something that close to the turbo, the price would not be a lot different considering you used a nice grade of Titanium.

 

The downpipe isn't supporting any weight and Ti would keep the heat in better.

 

The turbine housing attenuates a majority of the exhaust heat, so the downpipe does not see quiet the extreme conditions as the turbo manifold and turbine housing (hundreds upon hundreds of degrees less actually).

Unless a rotary is in question, Inconel on most exhaust components for a non endurance applications is cool, but not especially cost or usage effective. This is especially true for a sub 5-600 WHP ICE street car that only sees a few seconds on full throttle at a time or a trackday or TT street vehicle.

 

I don't think anyon is trying to make the case that an Inconel exhaust is a necessary addition to anyone's car here.

If I had the choice between Inconel and Titanium for the downpipe, I would personally choose inconel, which I did. I'm not sure I would want to track down a titanium flex section to weld into a Ti downpipe.