Header: Stainless vs. Mild

[My5ABaby]

I was looking at the Racing Beat site and they offer 2 versions of their streetable header. One is mild steel and the other is 304 stainless steel. RB notes the weight difference (7 less for the 304), but what are the other differences? I'd rather not shell out an extra $100 (or whatever the difference would be used) if it's not worth it.

P.S. Via my Google search I came across this gem: http://www.yarisworld.com/forums/showthread.php?p=193173. Hopefully that link won't derail my thread too much.

[Phoenix7]

i know that Starspeed racing is trying to make some SS headers like RB or SJD....look into those as an inexpensive alternative.

[sen2two]

Stainless real advantages over mild steel besides being more resistant to corrosion and rust is they dissapate heat better. but i would get the mild steel and ceramic coat them. around the same price in the end, but SS advantages can not compete with the ceramic coating.

[Roen]

Why not then just coat stainless?

[My5ABaby]

Why not then just coat stainless?
My understanding is that ceramic coating will lock out corrosion/rust (think of it as heat/moisture resistant paint) and insulate much better. This will decrease under hood temps and increase exhaust velocity. So basically it just uses the header as a structure to adhere to and could care less (to a viable point) what it's made out of.

[Roen]

You could then pay the extra $100 for stainless to save 7 lbs!

[Fidelity101]

You can loose that 7lbs somewhere else. Go with the higher quality material and if you want to get that ceramic coated inside and out and it is even more gains.

Just don't header wrap it if you plan on driving it in wet conditions because it will rot your pipes very quickly.

[vex]

You can loose that 7lbs somewhere else. Go with the higher quality material and if you want to get that ceramic coated inside and out and it is even more gains.

Just don't header wrap it if you plan on driving it in wet conditions because it will rot your pipes very quickly.

Usually you can use a silicon spray of somesort underneath the wrap to lock out water and moisture.

[Roen]

I'm inferring that stainless is a better material than mild steel, or do I have it backwards?

[vex]

I'm inferring that stainless is a better material than mild steel, or do I have it backwards?

Yes and no. Really depends on your application of what you desire/need. If you want a header that's not going to be wrapped and not going to be used to spool a turbo, then by all means go with the stainless.

If however you're going to be spooling a turbo the less heat that the header absorbs the better (however the cast Iron one's do quite well if not better at spooling a turbo). Your biggest thing you want is to make sure you keep heat in the manifold and not in your engine bay. Stainless steel is known to crack if not welded correctly in/on the manifold, it's also known to crack if you decide to wrap it. It all depends.

[Roen]

Great, thanks for the information.

As a followup, what makes the stainless crack if you decide to wrap it?

[Whizbang]

what really matters is the quality of the stainless steel. Cheap stuff cracks because generally its not the grade they claim to be using OR the flange and the tubing are different in material which causes a lower quality weld.

I would opt for stainless steel over mild just from what i know regarding materials. Even with a ceramic coating, you'll get rust eventually. Heat cycling, salt, moisture etc seem to work their magic on ceramic coatings. Then there is always the chipping aspects.

[Fidelity101]

it doesn't have to be stainless, it can crack when you wrap it. If you wrap it and then it gets wet it will hold moisture in there and with all the heating and cooling it will rot the pipes.

works great just not ideal for a daily or a rally car.

[josh18_2k]

there is a spray that goes over the wrap to seal it from moisture. its probably made my the same company that makes the wrap. REI or something? i dunno

[Fidelity101]

I haven't had any experience with the spray for moisture protection but if it works it works.

[Whizbang]

as far a moisture goes, i believe the area you reside would play a huge role along with WHEN you drive your car. If you take it out in the rain and often i can see it being a problem. But if you live in New Mexico and rain is rare im sure its not a need item.

[classicauto]

FWIW, I've had a downpipe and turbo manifold wrapped on my car for 3 seasons. The manifold back then was a greddy log, downpipe was stainless from ATP welded by me.

My friend has a set of (mild) headers on his 340. We wrapped them 6 years ago (first things I've ever wrapped) and they are still on the car doing fine.

I honestly don't know why people are paranoid about moisture.....there'll be more moisture INSIDE your exhaust from heating and cooling - we've all seen the little puke out. Anything getting on the wrap (which BTW, most companies recommend wetting it before install so you get a tight wrap) is going to burn off because of the SMOKING hot exhaust :)

[RETed]

In regards to wrapping...
It's not the moisture that causes problems.
It's the fact that the temp of the metal increases significantly due to the wrap.
This tends to kill WELDS first.


-Ted

[My5ABaby]

In regards to wrapping...
It's not the moisture that causes problems.
It's the fact that the temp of the metal increases significantly due to the wrap.
This tends to kill WELDS first.


-Ted
Good info.

With wrapping, has anyone had issues with RB headers? Or have any testimonials?
From everything I've read they're solid headers with good welds.

[Whizbang]

at the same time, rapid cooling is more likely to cause cracking than to high of a temperature. The wrap will remain the heat longer assuming its PROPERLY covered. Usually people have exposed areas, and these will cool much faster than the wrapped areas which will develop stress cracks over time in the thinner steel. You CAN have such a thick steel that stress cracking can't occur but that concept is not practical for the topic at hand.

A ceramic coated SS header would probably be the best bet overall.

[JunpoweR]

The moisture evaporates from the headers heating up.
I don't see how it can stay logged inbetween the wrap and header.
Fiberglass and Ceramic preg Fiberglass wrap (Do not use anything but Ceramic/Fiberglass wrap for rotarys)cannot trap water if you heat it up and while driving even if water gets onto the wrap it will evaporate in seconds due to heat.
I can imagine having wrap around mild or SS can reach higher tempatures, remember, when almost any type of metal is heated up it expands to a certian point and if overheated it will shrinking more than it expanded causing cracks and warping. All this is caused by many different factors, Pipe gauge, weld quality, material choice. Exhaust wrap is old school technology, get a good quality coating from JetHot.

SS304 had many advantages over Mild Steel.
Lighter - Stronger - Higher Temp and Corossion resistance.
The only advantage I can see that Mild Steel has is it expands and shrinks better because is is a softer steel than 304SS.

The only other way I can imagine why water would be a problem is when your headers are very hot and you hit a puddle and water splashes onto the hot exhaust metal cooling it down to fast causing warps and cracks in welding. Remember the weld is always harder than the metal around it. During welding, a filler rod is used causing the weld to cool and introducing a new alloy into the welding pool making that area harder than the steel being welded together, thus less expansion/shringage in the welded areas causing cracks and warping in those areas.

I would go with SS and JetHot Coatings.

StarSpeedRacing will be making SS304 Medium Primary Header and Mid pipe Combo that bolts up to any bolt on cat back, check out the GB section soon.