Zoomies - stainless or chrome?

It appears to me that I can build myself stainless steel zoomies for the same price as chromed mild steel.

What are the pros and cons to each?

I'm leaning towards stainless, I can weld on them later if need be and I don't have to wait for the chroming people.

 

Heavy is the main downfall to Stainless.

 

Surprised

I'm surprised to hear the weight thing since SS and mild are essentially the same density.
Do the SS zoomies have to use thicker material for some reason???

 

headers

Doesn't chrome retain heat. I remember it did on a chrome coil I had 30 + years ago. I never ran or chromed anything on the engine since then. Just an experience I had. Thanks Don

 

Stainless

I made a set of stainless zoomies over winter and are real happy with the outcome. They look good, easy to clean and have gone a neat straw colour. I had people tell me they would crack but it hasnt happened yet though we have only made about 30 runs. They worked out cheaper than mild steel and chrome/coating . Like you say- easy to repair if needed. Go for it.

 

Definitely. I made some steel ones and chromed them for our old FED. Lining the first 100mm or so of each pipe with heaps of grease stopped them from discolouring (don't know how or why that works, but it does), but they eventually started to rust. The cost of chroming was ridiculous, and they are probably nearly as heavy as a stainless set.

I've heard of the 'stainless exhaust pipes cracking' rumour too, but never seen it. Just one of those uneducated statements?

 

stainless

From experience the stainless will eventually crack. I have found using mild steel works best and get them coated. The ss seams not to like being heat cycled over and over.

Sean

 

Stainless cracking

Yes stainless steel will crack when exposed to vibration. Of course this is true with most metals. Here’s a track you mite try. Take a magnet and place in on your headers. Did it stick? If it did you have a stainless with high iron content (cheap). Stainless is just like aluminum, you can get it with different grades (6061, 7075, etc). If the magnet does not stick then you have a good set of headers. After you run the car a few times try the magnet again, if it sticks this time that means it has work harden and will start to crack. The B-58 Hustler Mach 2 supersonic Bomber (way before your time) was made primarily of stainless steel. The mechanics would walk around the airplanes putting a magnet on it, if it stuck; they know they would have cracking.

The cheap stainless steel I referred to was coming from Japan in the late 60's.

No, I did not work on the B-58!

Mack

 

I have two sets that are cracked, mild steel. That's why I'm looking to make more.
I'm not looking for them to last forever, these cracked ones lasted about 10 seasons.
Do the SS ones look as good as the chrome?

 

When I made my headers I buffed the pipes and plates with a fine flapper wheel on a bench grinder before welding. This put a nice satin finish on them and it also means that if they have to be repaired they can easily be buffed again to restore the finish. This buffing does remove the neat colour they have gone but as soon as they are run again the colour comes back. Before deciding what metal to make mine from I asked a few people who should know about the stainless cracking thing. Of the four people I asked, three said it will crack badly and one said it will be fine. When I asked more questions it turned out the only person who had actually made SS headers was the guy who said go for it. if I have to repair them in the future I will. If they can last five years I figure they will have done Ok. If they last longer even better.
Jim

 

I will try to load some photos. I think the SS headers look great and unique.

 

I love anything shiny..Dave "CHROME" lowe...oh mine are just mild steel smiley brand..love them with never a problem..with 4 haed seasons on them

 

If you build SS headers or zoomies CORRECTLY, with well thought out welds & gussets & sections & supports, then there are no cracking concerns at all.

Here are some thought starters. 409 grade stainless is what most modern OE's use for exhaust (cheap & a magnet will stick). 304 grade is suitable for most motorsports headers and is readily available (magnet will not stick). 316 or 322 can be purchased if you want to thin down the walls & save some weight or have extreme temp tolerance such as with turbo headers

I would not advocate coated or chromed headers if you ever want to weld-on, or add-on, in the future.

If worried about weight, why not Ti or Al? Both of those can be used too....

Check out Burns Stainless or SPD Exhaust. Get their catalogues.

 

What do the nitro guys use , they sure look like stainless some of them .

Quite a few production cars are coming out with stainless exhaust manifolds now so cant be that prone to cracking.

 

ss

I have used ss on turbo and blown they all crack. We have went back to mild steel and the results are much better with good preperation.

Sean

 

We use mild steel.

EDB