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I supported Toymods
Location:
Perth
Registered:
May 2002
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 Stainless or Not?
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Wed, 17 September 2003 12:27
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Hey guys,
I'm just trying to keep busy working out the engine conversion stuff so it feels like I'm getting somewhere 
Getting some quotes on exhausts, I've only got one so far, $820 for a 3" mandrel bent mild steel exhaust with a high-flow 3" cat and a stainless 3" muffler.
To have the full system in stainless I was quoted $1150 from the same people. I ask you, is it worth it?
Thanks,
Nathan
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Toymods Social Secretary
Location:
Sydney
Registered:
July 2002
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Re: Stainless or Not?
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Wed, 17 September 2003 12:33
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oooh, shiny. 
I too would be interested to hear this.
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Location:
Eskilstuna, Sweden
Registered:
May 2002
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Re: Stainless or Not?
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Wed, 17 September 2003 12:43
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Only if they mandrel bend it themselves and don't put the exhaust together from a whole bunch of pre-ordered bends that they chop up and then weld together.
If they bend it themselves you will get less welds and probably a better fit.........IMHO.
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Stainless or Not?
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Wed, 17 September 2003 12:45
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Okay, I've fired off an e-mail to them asking if they'll be bending it or they'll be welding in mandrel bends.
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Stainless or Not?
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Wed, 17 September 2003 13:41
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mine's a totally welded stainless system, 3" all the way thru
I must say I love the look of it.
stainless is great, in that it will never rust.
I've hear rumours it holds in the heat more (which is a bad thing) - but that's just word of mouth from 1 guy.
1150 for a full stainless system with cat and muffler is bloody good - take it!
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Stainless or Not?
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Wed, 17 September 2003 13:45
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See thats the thing, how prone is a mild-steel exhaust to rusting? I might just bite the bullet when I do, get all stainless, but if I'm never going to have problems with the actual exhaust rusting for as long as I have the car, I ask the question, is it worth it?
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Stainless or Not?
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Wed, 17 September 2003 13:46
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Oh, and wouldn't holding the heat in be a good thing because it'd keep the exhaust gas velocity up?
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Stainless or Not?
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Wed, 17 September 2003 13:53
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stainless (iron-nickel-chromium) alloys have a slightly higher heat capacity, and it's true that they lose heat slower.
as for mild steel, two main types. low or no aluminium, and high aluminium content. i forget what the actual amounts are, but the low/no aluminium will rust, and may rust pretty badly.
a good mild steel system will have aluminised steel, and also be welded with aluminised filler metal.
i could take a pic of my extractors to show the difference. after about 18 months, turns out the neds that i bought from "liverpool exhaust" (the ones that make hurricane headers i think??) was the shit mild steel, so two of my primary pipes are rusting, while the other two are absolutely fine...
crap mild steel might last.. 2-5 years maybe?? good will last a lot longer, and staino will outlive the car...
Cya, Stewart
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Location:
Colac, Victoria
Registered:
May 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 08:52
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I swear by stainless!
my ta22's system was 8 years old - and didnt have a spec of wear on it bar a few watermarks where mud had dried ..
AVO have quoted me a price of a shadew over 1300 dollars for a full 3 inch stainless/mandrel bent system - which is very good for a Gt4!
for the slight cost more - youll be happier IMHO
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 08:54
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I possibly might be able to scam a couple of the bits on my list a bit cheaper than I'd forseen.
If the finances allow, stainless it is, thanks for the feedback guys.
One thing, it is a welded system, is it really going to be that bad?
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Location:
Eskilstuna, Sweden
Registered:
May 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 09:06
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I should probably clarify a bit.
All systems will have welds in them (it's the number that matters - within reason), it is just that some places stick so many chopped up mandrel bends in one turn etc that there is almost more welding filler than mandrel bend (I am exaggerating a bit). I wish I had some pictures to show you what I mean
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 09:07
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I think I know what you mean dude. Someone has described it to me once before, where the welds are bad and they provide their own restriction.
This what you mean?
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Location:
Eskilstuna, Sweden
Registered:
May 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 09:12
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Exactly!.......
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 09:14
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Makes sense, hopefully there isn't a great deal of bends and much room for error 
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I supported Toymods
Location:
melbourne
Registered:
June 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 10:47
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the way i see it, when i get my exhaust re-done, it will be in mild steel, as the mild steel system on it now seems to have lasted ok for the last 20 odd years.
BUT if the stainless isn't too much more expensive, id go for it.
stainless is harder than mild steel to weld with a MIG though, this may mean something.
you do want to keep the heat in, this is one of the reasons you don't see aluminium exhaust systems. (and you do see, or at least hear of titanium systems)
i tried to look at the thermal conductivity of mild steel vs stainless, but can't find my materials handbook.
i wouldnt stress too muck about the welded together thing, as long as they know what they are doing it should be fine. if they TIG the pipes together there will be virtually no restriction at all.
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Registered:
November 2002
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Re: Stainless or Not?
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Thu, 18 September 2003 11:21
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Yep, welded bends are no problem at all if they are done properly. That is using a TIG welder and ideally purging the lines before welding (which I doubt an exhaust shop will do). A good welder will make it almost very hard to even see where the joins are. I just made a full 3 inch SS system for my Celica and I highly recommend it.
A couple of points about stainless. 316 is the highest grade and is fine to use around 1 metre from the exhaust manifold (on a turbo that is). Its fine to use 316 all the way with a NA engine. If its turbo, you should really use 304 or even 409 SS. Although its a lower grade, it can handle the high temps better than the 316.
Also, remember that SS has a tendancy to work harden and become brittle. So make sure it is well supported and maybe even consider a flexbile joint somewhere to take out the vibration.
Good luck,
Simon
http://users.chariot.net.au/~stmezz/celica.htm
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