Thanks for the awesome site, Tim. Looks like both materials have about the same specific heat capacity, but steel is a *little* better thermal conductor. So, why do all the Viper and Mustang guys report higher under hood temps when they switch from mild steel to stainless headers?

Below is the equation for thermal conductivity (k). The factor L is the thickness of the material used. Tim, since you're a fabricator (and I obviously am not), what is a typical wall thickness for a mild steel exhaust pipe? How does that compare to the typical wall thickness of a stainless pipe?

Is it possible the difference isn't material but thickness of the tubing used?

anyone know where i can get the flange that connects to the cat?

Yes, that's what I asked in the post above. The specific heat and conductivity properties are *very* close on both of the raw materials, so I'm thinking the diffence is in volume.

Isn't it the metal's inability to cope with it's expansion? IOW mild steel is way softer and can manage the expansion and contraction without cracking/tearing. Whereas stainless being harder will tear/crack sooner. I think that's why you don't see any super thick SS manifolds like you see thick mild steel.

I got mine here (https://www.headersbyed.com/), nice folks and the cheapest prices I could find. They do have a minimum order requirement though so you migh want to get a few other people together.

it's just a standard 2-bolt flange correct? you should be able to find tons of sources. call some muffler shops.


BTW i responded to your FMU post with pictures as requested....

Yeah my downpipe is 3", I didn't notice any difference in temperatures, I did when I took the cat out. The downpipe, as well as my exhaust, were fabricated by a local one man shop Garage Auto Hero, very nice guy and does awesome custom fabrication stuff, they specialize in datsun510's/ae86's, one interesting car in the shop is a bmw z3roadster with sr20det running 470rwhp. The best part is I only paid $240 for that downpipe, I think it's a steal!

Here's a pic of my new exhaust, just finished last week. 3" turbo back with just one muffler.
Attachment 217203

ok and when are you ready to get me a copy of that exhaust?!

I didn't buy a used kit off ebay. I did however find my car on ebay and it just happened to come with this shitty kit already installed. If you look at the link in my signature you can see how the WG piping is routed in a engine bay photo. It is in the exhaust instead of the manifold though. I'm running a HKS manifold right now, but not for long. This crappy setup is killing me.

yeah thats the ride. i can't believe how nice the rest of the car was done compared to the creative turbo setup.....

Yeah it's kind of funny really. That awesome stereo system that was in it. It was complete garbage, didn't work half the time. So i tore all of it out. Saved about 25lbs in stereo crap including the subwoofer enclosure in the floorboard. Replaced the deck, trashed the DVD player replacing it with a gauge face plate. So that is much better now. It's been running a Narrowband 02 gauge and sensor so I got an AEM controller w/gauge. Replacing that this week. The indiglo gauge faces have some wiring problem and don't work half the time. The IC piping is all powdercoated mild steel and is a terrible fit. Seriously took me like an hour and a half to reinstall all of it again because i had to bend the couplers so much. The oil lines were all high temp silicone with like five brass fittings coming off the turbo. Really i could keep going on. The built motor is good with the wisecos and pauter rods. The powdercoating is nice. The wheels are cool but heavy and the BFG KDWs are really nice. The body is nice with like 2 small door dings in it that I'll have fixed within the year. The alarm that is in it needs some major adjustment because it goes off whenever i start up my truck so it's way too sensitive(or my truck's too loud.)
So yeah, i'm pretty much redoing the car slowly but surely because someone didn't know what the hell they were doing. What blows me away is the invoice for the turbo kit.
T25- 620.00
HKS manifold- 424.99
Spearco IC- 524.99
Tial WG- 239.00
Tial BOV- 239.00
IC piping Powdercoated- 350.00
Oil lines- 75.00
Labor for Turbo kit- 400.00
Apillar guage pod- 35.99
T25 DP flange- 35.99
Autometer boost gauge- 52.95
Autometer A/F gauge- 58.98
Total For the crappies turbo kit ever- $3056.89


WTF was he thinking. Either way i got the car for less than dealer black book with less than 20,000 miles on the rebuilt solid motor. Clean body with one wreck in it's history, but that's non big deal. It wasn't the best deal ever but it was alright.

The car itself looks very nice! There are certainly a lot of high quality parts there, maybe the fabrication man was sick that week...real sick... If you want any of it refab'd let me know if I can help.
-Michael-

This thread is how NOT to build a down pipe, how about a HOW TO build a down pipe forum, for those of us that are about to??

Sexy looking downpipe Rus!

Very nice DIY stuff.

MarkP's setup might be ghetto, but I bet it kicks the Sh*t out of my setup.

How about a DIY manifold and DP sticky. Get everyone to post pictures of what they are running together on their car. Give some people ideas that want to venture making their own or having one fabbed up for them. A good visual archive so people know what a "megan racing" or "ETD" manifold really is and how it can be used.