1962 stailess exhaust points loss

[Chas Kingston]

Re: I gotta think your hangers...

Should be the same for Carbon Steel -- the coeffecients of thermal expansion are essentially identical.

Geezer

[Tracy C.]

Does stainless expand more than carbon steel?

Not much, but "some"....

If stainless systems expanded as much as some olds wives tales would lead you to believe, then how would so many OEMs use it and not have problems? The key is to look at a property of the material called the coefficient of thermal expansion (COTE-Geek terms for how much the material will grow when it gets hot).

For mild steel the COTE is:

6.3 X 10-6

For stainless, the COTE is:

9.4 X 10-6

So, to calculate the change in length we use the following formula:

=(COTE)(Length of component)(change in temperature)

Looking at an exhaust system that is 84 inches long, and whose temperature will change 600 degrees F, on average, for mild steel:

change in length =.3157 inch.

For stainless: =.473 inch

Most people never consider a "growth factor" in a carbon steel exhaust system, but it too can be an issue if the system does not fit well.

Mike, if you put carbon steel on the same car with the same pipe configuration, you would see almost the same amount of growth (under 1/4" difference)

tc

[Mike McKown]

It was standard automotive practice to process ex

hangers biased in the forward attitude for assembly purposes. This allowed for expansion and yes this was on regular steel pipes and mufflers. At least 40 year old knowledge.

[Dennis C.]

Thanks Guys...

For me, reading this series of responses,alone, has been worth the price of admission. Great stuff, great exchange of ideas from so many different perspectives. It was on my "watch" the current standard deductible percentages went into effect. Maybe in the future, they will be modified - maybe they won't. Whatever - not my call, but keep those cards and letters coming in.

[John M.]

Re: 1962 stailess exhaust points loss

Mike,
I don't have a problem with such a use. This is no different than a judge stating that a car appears to have BC/CC and ofering to let an owner pull up some color to prove it is not. This is completely different than checking a blacked out pipe with a magnet to see if it is stainless. The look of stainless fuel lines is completely different than TBW lines, but blacked out stainless looks just like blacked out aluminized or carbon steel pipes. I have no axe to grind since I have never owned a set of stainless pipes, but the whole concept just does not sound fair when viewed against the judging standards.

Regards, John McGraw

[Dave Suesz]

That's a LOT less than 1/4"...

Which is at the rear bumper. A year ago I spent a while in Machinery's Handbook on this same discussion. I'd have to say a system which could not stand .473" of expansion was a poor fit.

[Gary Bishop]

Re: Nobody's using original C1 pipes anyway...

I was at a Mid-Atlantic Chapter Meet, in the mid `90s, in Cumberland when an Exhaust Expansion test was done on Mike's `57. Many were surprised how much the pipes expanded out of the rear. At least 3/4 of an inch in about 5 minutes.

[John H.]

Re: I gotta think your hangers...

I put a Zierden SS system on my '57 six years ago, and did an "A-to-B" measurement comparison vs. a neighbor's '58 that had an aluminized steel system (both cars cold, both cars hot); the cold-to-hot expansion difference (measured from the tailpipe tips to the bumper outlet surface) was negligible - both expanded essentially the same amount (about 1/2").

[Geoffrey yoder]

Re: 1962 stailess exhaust points loss

To all who responded to my question on Stainless steel pipes I thank you very much. To clear things up, it was never a plea to the judges to bend the rules, nor a forum to advocate any specific use, etc. of that fine car the Corvette. I understand the passion of the sport, but hope that, as someone who is not a master Corvette restorer, etc. I can ask a question without having to incur responses that will detract from the purpose of the sport....FUN

I just wanted to know what expectations were. I am hoping to have my car be close to the 97% range, which would give me the unbelievable opportunity to pursue a Duntov award. Having talked to a an NCRS Judge some time ago, he did not seem to think my choice of exhausts would be a real big deal. But as I stated before, what do I know, thus the question.

It was my first time on this forum. It was looked at as enjoyment...

[Dave Suesz]

That's why the C1 had...

a ring supporting the tailpipe, so the pipe could slide through when expanding without binding. If you look at Mustang dual exhaust, you'll see even Ford understands this.