turbo manifold material type

[ProVK]

Green, bang on the factory cast iron manifolds swapped side to side, keep it simple and it will be fast.

[Hansel]

Green, bang on the factory cast iron manifolds swapped side to side, keep it simple and it will be fast.

I've got two pairs here for my vh. One pair to fuck up.

Good to hear.

[Supercrown]

321.

321 stainless was developed specifically for high duty exhaust system use on WW11 piston engined aircraft- it is next in the line of superiority to Inconel.
Countless properly designed fully welded 321 turbo manifolds have been made. Needs to be supported but not constrained- it expands seriously, like all SS.
It also acts as it's own barrier coating: the heat loss through stainless is under half of carbon steel and it is better performing flow wise because it doesn't scale up. Blackish colored with it's own aesthetic.
All Nascar pipes not made from Inconel are from this stuff.

Good info. Being a weekend hack I've always gone to food grade stainless but no further due to price and availability. I've also found that stainless gets a bit hard to work with using general weekend hack tools. inconel is the shit, but even on commercial jet engines and headers on piston aircraft they do make use of slip joints pretty extensively purely to reduce the chance of cracking. The thing about inconel pipe work that always blew me away when working in maint at Qantas was how thin and light it was. The stainless used on auto exhausts wouldn't last 3 minutes under the same conditions, yet the inconel pipes can see hundreds or thousands of hours at spastic temps. I did a bit of googling on inconel piping, and for exhaust runner size it looks to be at least 5 bucks per inch! Not to mention that you need a very skilled welder to do the job properly. We had special weld Bays that ensured the pipe was gas purged or the whole part could be dropped into a gas bath if the part didn't lend itself to being sealed with purge bungs. I recall that in the event of a pipe needing to be repaired that bends were obscenely expensive, but some of that was due to the fact that the bends were 'certified' for aircraft use.

[Momus]

I imagine, and hope it would all be proper process at Qantas. I worry about the loss of skilling and the quality of the consequent work when I hear about 'maintenance' being subbied off to who knows where.

I make headers for rotaries from time to time and because of the Wankel's general hopelessness at extracting much energy from a given amount of fuel, the first part of the exhaust (and often all of it) acts as an afterburner. They run red hot for the first 2 metres. I've used 321 for these but availability and price put a stop to that. I now make them- and the rest of the system out of 304 food grade as well. The factory supplied rotor housings used to come with an Inconel exhaust port insert organised with an air gap to prevent the alumium housings copping too much heat.
Provided it is supported but can move, the 304, or 316, lives very well. Slip joints are the go of course, but for someone who only does occasional exhaust work organising for precision expansions- and properly round tube to start with -can make it a bit arduous.
I organised to make an Inconel exhaust to save weight on one system. A pommy mob, makers of exhausts to the funded gentry, aka F1 and the like, were reasonably priced for straights and bends. The make their own tubing to spec in 3' lengths from .6 mm sheet.

[10sec rx7]

stainless sch10 butwelds

glow like that for a hour at a time..

remade them out of 304ss 1.6mm 2in bends and done 2 seasons so far ok..

[chartreusehj]

thats a fucking cool pic Dale.

might have found a welder of 304/316 but he looked at me funny when i mentioned 321 lol.

I think my best course of action is a MS set, make the fucking thing run and worry about better pipes at a later stage (if required) because theres every likelihood the engine life will be shorter than the pipework.

Cant argue with Provk's logic given his results so instead ill ignore it, 90% stubborn/10% stupid but those who know me might argue the numbers :D

[Hansel]

God I wanna fuck the shit out of that motor.!

[Hansel]

Just out of curiosity. How much for Inconel Momus?

[Supercrown]

Get the gas to the turbine any which way you can brother. As weekend warriors, ability to easily obtain and work the materials is as important as performance. Might not deliver the most elegant solution, but at least it's obtainable!

[Hansel]

Who's done pvc cooler pipes? C'mon. Fess up.

[Momus]

Just out of curiosity. How much for Inconel Momus?

About $45 a foot for 1.875". It is usually only used for headers and is supplied only in 400 mm lengths from that vendor. Extra for bends.

Green.

I'd agree with Super and Pro and do it the simplest way- probably with the headers reversed and modified if needed.

[Hansel]

That is a few 0's less than what I was expecting. Mindblown.

EDIT: is 0.6mm it? What's f1, aviation?

Thanks for not making me Google it. Buddy. Pal.

[hrt5l]

Another vote for reversed headers, if they fit why cause yourself all this extra trouble and expense for no gain.

[Cameron_Datto]

Any one used these guys? http://www.goair.com.au/?page_id=72

[200MPH]

I was in the pressure fabrication game for a few years a while ago and we made equipment from all sorts of 'exotic' materials. 321 is similar to 304 stainless except for addition of titanium to prevent chromium carbide formation around HAZ, which tend to ruin the corrosion resistance of 304 or 316 SS. From memory use 347 SS filler wire when welding 321. 321 is fine, but doubt you'll get any benefit in this application compared to 304. Both should have similar thermal expansion etc. But I'm going off 13 years past memory here!
Contrary to Momus, after grades of aircraft turbine alloys, inconel and the like, the next best creep resistant high temp alloy that is sort of available is/was Avesta 253 MA. That stuff is good out to just past 1000deg C in pressure vessel use and is black, looking like carbon steel. 321 is not black, looks like any other stainless.

Anyways, back on topic... My bridge ported turbo rotor used to see a fair bit of supersprint work and I used heavy wall pressure pipe and elbows to cope. But if manifold is not supporting the weight go normal exhaust pipe I guess. Don't imagine your car will cop much circuit work, if not not like you need to go expensive with materials.