Headers -- Stainless or Mild Steel??

Opinions sought from the folks that make up this fine list.........which material do you prefer for headers? Also, if there is a particular grade of material, please add that as well.

thx!

Stainless if you can afford it. Lasts longer, holds more heat in.

Yep, depending where you live mild steel might only last a few years. stainless is always the best option expecially if you plan on using header wrap

I always make them from 304 stainless. Google up "sanitary tubing." Polished inside and out, mandrel bends readily available. I use that for NA applications. Schedule 40 for turbo applications.

It depends on how many miles you're going to put on it.

Stainless stays nicer looking, but it cracks very easily because it has similar properties to frozen peanut butter. It's very weak and does strange things with heat attached to it.

As a rule, mild headers rust, stainless headers crack.

There is a famous troll in the British car world that says you should never use stainless for headers. Too bad he gets banned before he can pass on his knowledge.

spitfirebill wrote: There is a famous troll in the British car world that says you should never use stainless for headers. Too bad he gets banned before he can pass on his knowledge.

Gareth or GT or The Estonian?

All of the above. I see you know him too.

If I ever go turbo, I work in a powerplant so I can get my hands on P22 for header material. (something like 12% chrome, for high pressure, high temperature superheaters) Stainless numbers starting with 3 are austenitic and good for corrosion resistance. Really high temp stainless is ferritic and the numbers start with 4.

https://www.cartech.com/techarticles.aspx?id=1670

Since you didn't give any guidance on how much of your money we're free to spend, I vote for 321 stainless. Expensive but it'll last a very long time. Or just go with best, - Inconel - at about $200 per 180 degree bend, but it'll outlive the car.

You need to give a budget constraint...

Cost isn't really the issue here, but we'll stop short of Inconel

Having said that, does some of the recommendations change if the headers will also be coated and wrapped. Car will be for auto and track primarily. A very infrequent trip on public roads and no wet weather driving are also to be considered.

In reply to orphancars: I hope you realize that headers, real headers aren't simply a matter of some tubing. The size of tubing (Bigger may not be better) as well as the length (all tubes must be the same length).. are critical for power production.. OOPs I failed to mention collector length..

There are a few places that will help you get close to the right design for a real header.. Once close use a computer program to finalize exactly what you actually need.. I use Engine analyzer by Performance Trends.. Back in the early days of computers when I'd build an engine, put it on a dyno and print out real numbers. Performance Trends always wound up being closest.. What I liked most was the ability it allowed to replicate factory numbers and then use those adjustments to correct for the weird engines I'd build..

I'd spend several days trying different sizes, lengths, and collector lengths. Then make slight changes to timing, fuel, or camshaft etc.. before changing tubing size length or collector length. It would be wortrh it because the final numbers I wound up with were almost always different from what I started wiith..

In reply to frenchyd:

Yeah -- pretty clear on the mechanical aspects of header design (tuned length, resonant frequencies, collector length, etc, etc) -- just looking for material opinions/info here. And real world experience on wrapped vs unwrapped for a non-street car.

kthxbai!

Don't wrap. It accelerates rust and heat related failure. If you feel you must wrap, get it ceramic coated internally and externally beforehand.

iadr wrote: So, show me an OE "header" that's been made of anything but stainless since oh, the mid 70's.

They also tend to have accordioned sections to accomodate expansion. I haven't yet seen aftermarket headers that feature this.

I've also had to weld up the cracks in a few OE headers.

Jet hot coated steel or equivalent????

I make mine out of mild. Easier to get and weld, less liable to crack, no real issues with rust in the real world for a track car. If you want to spend extra money, spend the money on a good ceramic job like Swain instead of whatever your local powder coat shop claims will work.

I have rusted/burned through a stainless header with wrap. I've never rusted through any other header and never wrapped another one.

I made my own header from 321 stainless and it was wrapped for two years without issue. However, I recently removed the wrap, partly because it was falling apart, and partly because it "sheds." I found thousands of tiny bits of the stuff stuck to everything in the engine compartment. What bothered me more though was that since Midlana's an open-top car, I was likely inhaling that stuff... no more.

Oh, don't forget that if you get the header coated and it later cracks, you're screwed since you can't weld to it. Also, I don't know of any place that guarantees they can get an even internal coating, outside's no problem. (I did get my turbine housing coated with the Swain "white lightning" - great stuff and it never discolored.