eLTwerker

Sould I get turbo piping made of stainless steel, coated or what? I'm more interested in longevity and performance. Cost is a factor, but $600-$700 more is not a problem.

NassyVette

iTrader: (22)

If you can afford the stainless go fo it. It won't rust and I find it easier to weld. Mild steel is cheaper and will work just fine as well. If you get the aluminzed or coated steel piping you'll have to scrape off the coating before you weld.

HUNTER02SS

iTrader: (24)

I get the stainless steel and then have it coated.

Whistler

iTrader: (46)

Coated stainless is the best. Mild steel works fine too, it will eventually break down from the heat though. It depends on how hard you use it, and how often.

02SSLE

iTrader: (26)

I found from my last turbo kit from a sponsor that used to be on here that stainless will not hold up to the extreme heat cycles. The stainless cracked several times and had to take off to be rewelded. My new kit that a good friend and I built we used mild steel. no problems at all.

Whistler

iTrader: (46)

IT depends on how the kit was engineered, and the grade of stainlesss used. 304 SS expands more than 321. Unequal length primaries with no slip joints made in 304SS will tend to develop cracks over time. 321SS with slip fit collectors won't have this problem.

Carbon steel will scale and break down over time, from the inside out.

eLTwerker

What about coated mild steel?

black98ws6ta

iTrader: (77)

Ive used coated mild steel on street cars to stay away from cracking due to heat cycling.

Whistler

iTrader: (46)

Coated mild steel is great. Just over time it scales away from the inside out. How much and how long depends on how hot you get it, and how long it stays that hot.

eLTwerker

So coated mild steel would hold up longer than stainless steel or even coated stainless steel?

Also, just to be sure, what are we talking about coating the mild steel (or stainless steel) with?

Whistler

iTrader: (46)

Mild steel doesn't expand as much when heated, so it is better for resisting cracks, but is less durable in terms of how much heat it can take before it starts to break down.

koolaid_kid

iTrader: (21)

If I may paraphase: If the joints are welded, rather than slip fit (which I assume allows for expansion/contraction to work itself out) than either grade of SS may develop cracks? Just attempting to understand.
Thanks.

Whistler

iTrader: (46)

321 will endure the stress better than 304 in that condition, based on my experience. ( a lot of headers come through my shop )

koolaid_kid

iTrader: (21)

I understand, that is what I thought (you do a lot of systems). What type of coatings are applied to each, the SS and/or the mild steel? I have heard of such as Jet Hot, but perhaps SS requires a different type of coating?
Would 321 still be susceptible to cracking under these conditions, because they are bolted to the exhaust ports? Or would they be largely immune, due to the higher quality of SS being used? I realize that no system is immune to this issue, but would they still be suspect?

Whistler

iTrader: (46)

The same coating is applied to each metal.
321 may still crack without slip joints, but not like 304. That being said, many people build turbo parts from 304 with no slips and never have a problem.