Why? Care to elaborate?

 

Stainless steel tubing is prone to cracking. Cast stainless would be better. IMO

 

Well, the prototype SS manifold in the picture uses cast SS fittings, though I can't tell which alloy without better photos. Stainless steel is actually an excellent material choice for high-temperature/pressure applications, depending of course on the alloy used... there's SO many! I imagine he used some industry-spec 304/304L/316/316L fittings - it'd be feasible to duplicate the internal channels prior to assembly and final welding.

For EXTREME applications, Inconel or one of the Hastalloy (sic) series are more appropriate, but those conditions are a bit more severe than the inside of a turbo diesel exhaust manifold!

 

Obviously you've never seen what goes on inside my manifold. I got mine so hot so many times I had to beat my v-band off my downpipe with a hammer.

 

The logic is, the more brittle stuff, the eaisier it is to crack when it expands?


I'll believe that. I've worked with Hastalloy steel before, and that stuff is so brittle I've snapped it in pipe benders. If it gets hot it'd be more malleable, but then once it cools it might not like to go back to the way it was.

Instead of Blue having to whack it off with a hammer, he might have to use a blow torch to get it off in five pieces...

My logic close to correct?

 

Right, stainless tubing would be prone to cracking in enviorments like diesel apps. towing and drag racing/sled pulling can excede 700 degees celsius easy.
With the ever tightning emissions standards, operating above 700 celsius will become more the norm. The new CR engines in stock form are rumored to be able to run @ 1450 F all day long.

 

I've got the flux capacitor on order. Can't wait to hit 88 mph!
Oh and I ordered a rount tuit also

 

Stainless tubing - or most other high performance alloys, for that matter - tend to crack in elevated-temperature service due to thermal cycling - especially thermal shock - rather than from the high temperatures themselves; in fact, these alloys become more plastic instead of more brittle as high temperatures are reached.

There are literally scores of ferrous-based alloys such as 300 & 400 series, Inconel, Waspalloy, Hastelloy, Battellalloy, etc. that were invented just to perform well in extreme environments, such as nuclear reactors or turbine engines. Do you think the environment inside of your exhaust manifold is more severe than the conditions experienced by the turbine blades or afterburner nozzle of a Super Hornet's F414 jet engine?

700*C is ~ 1300*F, if memory serves - that's a couple of hundred degrees lower than the internal temperatures of the combustion chambers we manufacture, which use nothing more than lowly 304 series SS for all of the metal parts. I have 100K's of miles on a set of 304SS V-10 headers, and they still look like they're about a week old.

FWIW, these alloys don't experience stress-cracking due to high temperatures until 1700*F - 2000*F

 

what are your EGT's? do you have 30lbs of turbo hanging off of each one?

 

Diesels can go from 300 degrees to 1600 in seconds. I would call that severe heat cycling.

My point was, who would look to buy that manifold? Somone in stock form? Most guys who would concider that manifold would be pushing the fuel hard. IMO cast stainless would be better.

Besides, as we all know the intake side is where we need help.

 

What? You don't know that EGTs on a gasser will melt the aluminum pistons when you surpass 1500*F? You've never seen a turbo hanging from a header?

Again, thermal SHOCK is far more destructive than thermal cycling, and your exhaust manifold doesn't thermally cycle from 300*F to 1600*F in seconds - your Exhaust Gas Temperature does. Cast stainless may or not be better, depending on the alloy, but in any case - the fittings he used were cast stainless....

As I posted earlier, I don't think you could get better performance/dollar than an ATS-type exhaust manifold. I agree with your point - who'd buy a partially finished prototype manifold?

 

my question stands... what are your EGT's in that V10 application and do you have a turbo hanging off of each one?