what is the best meterial to use for a turbo header?
what is the cheapest matrerial one could get away with?
the header will have to at least partly support the turbo's weight.

TIA

 

Best (w/o going insane) would probably be 321 stainless. Cheapest I assume would be mild steel... go thick though, probably at least 12-14 gauge.

 

OK, thanks for the reply.

 

actually, the best would be iconel material. But that **** is beyond expensive. Most people use the 321 stainless but that is pricey too

 

No, polished titanium, like what was used on the recent Rad Rides car is way beyond expensive.

Most materials are a compromise, Inconel is a pain to work with and probably has a excessive temperature tolerance for the application. Other lower grades of stainless are OK, but have the drawback of expanding at a much higher rate then other steels and cast materials, so for long term durability you’d have to include expansion joints or sections of flex pipe to allow the structure to move a little rather then crack.

Your 2 biggest concerns is durability and heat retention (allows you to run a bigger, less restrictive turbine which will be less of a restriction). With just those 2 considerations I’d consider stainless schedule 40 weld el’s… OTOH, you’ll end up with a very heavy and fairly hard to work material. Personally, I think mild steel schedule 10 and 40 steam pipe is a best bang for the buck solution, and in a lot of ways better then the thinner gauge stainless, where 16ga 321 or inconel is the accepted ‘high tech’ answer. I know that there are a couple of makers of turbo kits for mustangs that use 16 ga mild steel, but I have no idea how long they last.

Mostly it’s a compromise between what you can afford, what you have the equipment to work, how long you want it to last and what characteristics you want for the exhaust system.

 

The Chicayne's headers aren't really titanium like the articles said. If you look at one of the captions it says the ehaders are 321 series titanium, or something like that. The author of the article must have made a mistake in his notes because there is no such thing as 321 series Titanium. Titanium alloys are not even designated like that. What the author should ahve siad was that they are 321 stainless steel, which CONTAINS titanium as part of it's alloy compostion. Actual titanium is not recommended for turbo headers, it's even stated in the Burn's and SPD catalogs.

My current headers are 16 gauge 321 stainless, but I'm going to make another pair this year from Inconel that will feature better tuning of the primary's and I'm going to utilize Burn's new double slip merge collectors. I haven't put enough miles on my TT engine to say whether 321 is the best option, but from the other systems I've seen they do hold up. As mentioned, you need to account for some thermal expansion, and you also need to provide support for the turbo so that the headers aren't supporting it's weight.

 

Monty, have you run that thing of yours at the track yet and if so what were the times? What sort of speed have you had it upto?

Also, I'm still holding out for some video of the beast unleashed.


Thanks

Robert

 

Monty, I’ll believe that they didn’t use titanium for those headers (I thought it was a bad choice when I read it), but I have seen at least 3 sources listing them as titanium and they did have a slightly funky look to them. But the explination for the mistake doesn't make sense, 321 doesn’t have titanium in it. Titanium is usually alloyed with aluminum to make it into a useable alloy and neither will alloy with steel. I could go look up what the steel is actually alloyed with to make 321 (not in the mood to get off my butt right now and find a book), but I’d guess that it’s mostly fairly high nickel content, chrome and very low carbon compared to the others.

You mind if I ask an unrelated question? What do you do for a living? Seems like you're working with a budget that most of us couldn't really imagine justifying and I'm betting that I'm not the only one wondering.

 

Well, I was in the mood to look it up....I'm not a metalurgist, but according to this excerpt from a metal supply website, 321 stainless steel DOES have titanium in it's alloy composition:

Type 321 Stainless Steel
Description

Type 321 (UNS S 32100) is an austenitic chromium-nickel steel containing titanium. This grade is recommended where it is preferred to omit the annealing operation after welding. It is also recommended for use at temperatures between 800-1650°F. This alloy also is not recommended for use in decorative applications.

Chemical Composition

Carbon Manganese Silicon Chromium Nickel Titanium

0.08 max. 2.00 max. 1.00 max. 17.00/19.00 9.00/12.00 5xC min.


RMK,
I'm going to run it this spring when the tracks reopen. I bought my wife a digital camcorder for Christmas, so as soon as winter lets up here in Chicago, I'll get some videos. In the meantime, I'm "tweaking" everything. I've got the turbo system apart right now, getting everything ceramic coated, polished, changing fasteners, cleaning up the way I initially routed wiring and plumbing, etc.

 

Monty, you beat me too it... I did a search for it also (actually checked a materials book) and found that the silicon is added as silicon titanium and most of the titanium percipitates out, but there is some left in it (I’m not even sure that that is a good description since I later did a web search and found something different at every site…)

What I was more curious about was the consequences of using Ti for exhaust (remembered that the ZO6 uses it), and found that it's actually a very good material for it, it's more workable/formable the 321 (321 has a tendency to kink when bent which is the reason that you won't find anything but mandrel bends in it, where Ti doesn't) and fairly heat tolerant.

Again, I'm wondering if it really was a mistake or if they were actually made of titanium...

 

Like I said, I'm no metallurgist, but I knew 321 stainless had titanium in it. When I was designing and building my headers, I spent alot of time trying to find a source for 3/8" 321 ss plate to use as material for my flanges. I came across alot of technical sites and upon reading them, the titanium content caught my eye.


I'm not sure if the exhaust manifolds on the Z06 are titanium though - it'd be interesting to know for sure. I know the exhaust and mufflers are.

Anyway, titanium is fine for a NA engine maybe, but for a turbocharged engine none of the distributors like Burn's or SPD recommend it. It would be fine for the exhaust, like I think it is used on the Z06, but 321 ss or Inconel would be recommended for the headers.

I just think the author of the story got his notes mixed up and just wasn't personally familiar with the alloy compositions and nomenclatures. Someone probably mentioned that 321 has TI in it, because it makes it sound exotic, and the author ended up hearing "321 series Titanium". Trepanier and Meany know their stuff, and their previous TT systems have always been 321 as they should. Even thoughy "chicayne" is a show car, Trepanier/Meany build cars that are well designed and made. They wouldn't make the mistake of using the wrong materials, especially when the customer has an open checkbook.

 

yes i am working with a rather tight budget, in fact the turbos will most likely have to be junkyard finds. I will probably wind up using mild steel, essentially for the money part. also i'll want to experiment with turbo placement since i want to keep ALL my accessories, especially a/c - although the smog pump may have to go. i figure with a cheap enough material i can try out different placements, and redo those parts i will mess up on without having to scrap the project due to lack of funds.
In any case this is a rather long term project, just gathering as much info as possible before i finally get around to it.
Thanks much for the very detailed answers