quote Originally posted by jeffndebrus: So, other than asthetics---would there be an advantage to having stainless tubing over black iron weld els???

Light weight, higher melting point, corrosion resistance and if you purchase mandrel bends, fewer welds.

[This message has been edited by Joseph Upson (edited 06-24-2007).]

i see no reason why you would need stainless. mild steel would be fine and i would use that before using any cast iron. cast anything is very brittle once welded unless done right. theres no need for tri-mix on a fiero "stainless" exhaust. its very low grade and welds just like mild steel. i welded my exhaust w/ .030 carbon wire and c25 gas and had no problems with burn through or penetration.

it sounds like sanderson is comparing welding 304 stainless to the fiero exhaust. theyre completely different

quote Originally posted by Hurricane: i see no reason why you would need stainless. mild steel would be fine and i would use that before using any cast iron. cast anything is very brittle once welded unless done right. theres no need for tri-mix on a fiero "stainless" exhaust. its very low grade and welds just like mild steel. i welded my exhaust w/ .030 carbon wire and c25 gas and had no problems with burn through or penetration. it sounds like sanderson is comparing welding 304 stainless to the fiero exhaust. theyre completely different

Mild steel is fine but it needs to be at least 16 gauge and having burned through 18 ga mild steel on a turbo setup myself. I wouldn't use mild steel between the turbo and cylinder head unless it was 14 gauge and I prefer cast iron manifolds directly from the cylinder head bolted or welded to mild steel to the turbo because they can take the glowing heat from the kind of driving I do and I believe they will outlast pretty much any header setup over time and heat cycling. The old cast iron from the early days might have been brittle and prone to cracking, but this new ductile, silicone blah, blah whatever GM calls it is pretty darn good, and has taken everything I've thrown at it over the past 5 years and I have really lit them up nice and bright. The manifolds from the 3500 are really nice because they are runner style instead of log.

It only takes having to redo a turbo setup one or two times for cracked pipes and leaks due to flimsiness to make you look for a sound solution. The more fatigue resistant the metal of choice the safer it is to wrap it to reduce engine bay temperatures provided proper relief for expansion is included. My biggest fear has always been exhaust failure with my setups from what I experienced in my earlier projects.

quote Originally posted by Hurricane: i see no reason why you would need stainless. mild steel would be fine and i would use that before using any cast iron. cast anything is very brittle once welded unless done right. theres no need for tri-mix on a fiero "stainless" exhaust. its very low grade and welds just like mild steel. i welded my exhaust w/ .030 carbon wire and c25 gas and had no problems with burn through or penetration. it sounds like sanderson is comparing welding 304 stainless to the fiero exhaust. theyre completely different

The stock Fiero exhaust is 409 stainless stainless. This type of stainless has about 12% chromium but no nickel. It will rust mildly but is much more resistant to serious rust and high temperaure oxidation than carbon steel. 304 stainless is 18% chromium and 8% nickel. It will not rust and is even more resistant to high temperaure oxidation. The recommended filler to join 409 staineless to itself or 304 stainless is 309 stainless (not availablee as MIG wire but widely available as rod for TIG). The recommended filler to join 304 stainless to itself is 308 stainless (available as MIG wire). Both 308 and 309 stainless contain much more chromium and nickel than even 304 stainless.

I have 308 stainless wire. You will blow a hole in either 409 stainless or 304 stainless tubing if you hesitate for the slightest moment with the MIG gun. If you turn the wire speed or voltage down then it just goobers on.

409 stainless or 304 stainless can be welded with carbon steel wire. It's easier because you are welding with a filler that has a lower melting point than the parent metal. But if you weld stainless tubing with carbon steel wire then you are somewhat defeating the reason that you selected stainless tubing in the first place i.e. superior high temperature oxidation resistance. I can't argue with experience that says the welds are holding up okay but welding stainless using with carbon steel wire is not conventional practice. Check the Burn's Stainless websire for more info on recommended welding practices for stainless tubing.

quote Originally posted by sanderson: I can't argue with experience that says the welds are holding up okay but welding stainless using with carbon steel wire is not conventional practice. Check the Burn's Stainless websire for more info on recommended welding practices for stainless tubing.

Good information and yes it does weld much easier. As for how well the welds hold up I would imagine it's because the weld bead is considerably thicker than the tubing and I use high temp paint so joint corrosion is not a problem. I'm not a professional welder and don't recall anyone asking me what type of welding wire I wanted when purchasing it over the past 10 years after I specified the size. Since none to my knowledge here is running a system with the demands that Burn's tends to build for maybe it's not an issue. I certainly wouldn't want to make things harder by switching to stainless wire if it isn't necessary at our performance levels. It's good information to know for future projects.

Sent you a PM! Goober!

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Ok Stupid Question;

If using the stock flange connections to our manifolds--that tubing is only 1 1/2"---
How to graduate it up to 21/2"?
Or can you bolt up 21/2" header flanges to our manifolds??????
Thanks Jeff

Collecting parts--- 2 1/2" in/out by 4" length flex joint
T-4 turbo flange
Wastegate flange

You don't want to make the tubing between the engine and turbo to big, 2" in diameter is about as large as I would go from each bank feeding into the flange and for a 3.4L I believe that's too much especially for 10psi or less. 2.5" would be a good size for the exhaust.

quote Originally posted by Joseph Upson: You don't want to make the tubing between the engine and turbo to big, 2" in diameter is about as large as I would go from each bank feeding into the flange and for a 3.4L I believe that's too much especially for 10psi or less. 2.5" would be a good size for the exhaust.

Exactly!!! What spools a turbo up quickly is fast flowing exhaust gas. Going to a larger size crossover will slow the exhaust flow into the turbo and kill much of the low end performance. IMO a stainless steel crossover is a must, as mild steel just does not hold up under the intense heat. We also wrap the crossover pipes here with heat insulating exhaust wrap. Whne exhaust gases cool they also lose capacity and that slows the flow and the spooling as well. The ss crossover on my 3.4L turbo has been wrapped for five years and is still in like new shape- a good testimonial for using high quality stainless for the crosssover. After the turbo just follow Joes suggestion above

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

You mentioned some things I have been concerned about Dennis. I'm using 16 ga stainless and would very much like to wrap it but I can't seem to find much info regarding dependability with heat wrapped stainless to the turbo. The tube temps get pretty high already and since I haven't been able to find 14 ga stainless mandrel bends I've been skeptical about wrapping the tubing to the turbo for fear I might burn through it although my fears are mostly from an incident with 18ga mild steel tubing.

Since my cast exhaust manifolds for my current build have blended runners I'm considering wrapping them also since they are modern castings that should be resistant to warping or cracking. I want to get rid of the engine bay heat that I have dealt with in the past and would like to use a good coat of HT paint, rap the exhaust from the manifold to nearly the tail of the car and then paint it with HT paint also.

I want to maintain an engine temp in the range of about 160-175 deg with a tstat and eng oil cooler to keep internal engine temps on the low side. I've run an oil temp gauge before and measured 230 deg oil temps on a turbo motor with about 180 deg water temps and since oil will be sprayed on the bottom of the pistons it would be to my advantage to keep the oil near the minimum effective temps.

quote Originally posted by Joseph Upson: You mentioned some things I have been concerned about Dennis. I'm using 16 ga stainless and would very much like to wrap it but I can't seem to find much info regarding dependability with heat wrapped stainless to the turbo. The tube temps get pretty high already and since I haven't been able to find 14 ga stainless mandrel bends I've been skeptical about wrapping the tubing to the turbo for fear I might burn through it although my fears are mostly from an incident with 18ga mild steel tubing. Since my cast exhaust manifolds for my current build have blended runners I'm considering wrapping them also since they are modern castings that should be resistant to warping or cracking. I want to get rid of the engine bay heat that I have dealt with in the past and would like to use a good coat of HT paint, rap the exhaust from the manifold to nearly the tail of the car and then paint it with HT paint also. I want to maintain an engine temp in the range of about 160-175 deg with a tstat and eng oil cooler to keep internal engine temps on the low side. I've run an oil temp gauge before and measured 230 deg oil temps on a turbo motor with about 180 deg water temps and since oil will be sprayed on the bottom of the pistons it would be to my advantage to keep the oil near the minimum effective temps.

Joe: We didn't get overly scientific when we did the turbo setup. We just used 16 gauge stainless mandrel bends cut and pieced them together with a mig. We did wrap the crossover only as the engine has Sprint ceramic coated headers which are holding up fine. The crossover has been wrapped in one layer of 1" W exhaust heat wrapping and it has held up for the past 5 years and still appears to be sound. We don't run an oil temp gauge so I can't help your here but the engine has always run a 180* thermostat and Mobil 1 15W 40 synthetic oil. The turbo still appears to be clean as a whistle with no coking or carbon as inspected with a bore inspection gauge lowered in the oil intake port. We did find that a #10 AN return line was necessary to return the high oil flow to the turbo with the unrestricted 3/8" line going to it. We run more il through the turbo as it's oil and not water cooled. More oil = lower turbo temps = longer bearing life.
Cooler oil always gives better lubricity but 100% synthetic oil can run pretty hot and not break down. I've run overheated engines that were only saved from damage becuase the oil kept doing its job. I'm sold on Mobil 1, especially for use in a turbo engine.

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87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
re-programming & odd electronics stuff
" I'M ON THE LOOSE WITHOUT THE JUICE "

Appreciate it. I'll wrap it good then, since I'm using twin turbos the heat shouldn't be as much as it would be on one turbo with two banks feeding into it. As for the oil I'll use nothing but synthetic but I'll probably bump my baseline pressure up a little and run lighter 0/20 synthetic if that's the correct weight I recall seeing, I'll have to investigate further to make sure there is more benefit then risk otherwise I'll stick with the 5w/30.


Get to work Jeff

[This message has been edited by Joseph Upson (edited 06-29-2007).]

It can be done with a mig welder, But you have to be extra careful, I wish You lived closer, Because it would be easy for me to do.
I have sucessfully welded steel to cast iron before There's alot of things that can be done with a welder, I would reccomend sending it to me, But my homedepot welder is broke and out of warrantee So I have to save for a brandnew welder.

?? Maybe buy two of these??
http://cgi.ebay.com/ebaymot...QQrdZ1QQcmdZViewItem

$30 shipping for a tube that weighs about 1.5lbs. How about something more practical from one of these sites: Mild steel and stainless, I usually end up going with who has the best price on what I need, some have better prices on one type of metal and another on something else, I believe the second link has the best price mild steel straight tubing and some mild bends.

http://www.stans-headers.com/parts.htm
http://www.schoenfeldheader...m/U%20&J%20Bends.htm
http://www.mandrelbendingso...35&start=13&total=61
http://store.racing-solutio...rg/mandrelbends.html
http://www.profabrication.c...ges/profab%20304.htm

[This message has been edited by Joseph Upson (edited 06-29-2007).]

any update Jeff?

I went to the junkyard the other day and scavenged some stainless mandrel bent GM tubing although previously used-lol $11.00
I was happy to find one of those expansion joints and a nice Y pipe-----The problem is I don't have a clue where to begin and I haven't figured out how to transition from one size to another which will be neccesary going from the stock manifold flanges to the tubing I bought. I might have to order stainless " cones " to do that. It will be extremely difficult because I have no way of bending tubing and the turbo cannot be moved much because of the strut tower. And I have to clear my muncie shift cables etc.

[This message has been edited by jeffndebrus (edited 07-04-2007).]

Jeff some things went south with me and a relative although it was 7 or 8 months ago now and a project car I had in the warehouse went to a salvager. The car was located off Beaver street about a mile or two headed away from the bridge on the open market side. There are some salvagers on that side so it might not be far away if it hasn't been crushed, it's a white 84. I got my turbos and exhaust off the car before things went south, but the engine is a like new 03 3400 V6 with mildly ported 2.8 heads. It also has a new fuel pump and ignition module and 23 lb/hr injectors so if you can find it you might be lucky enough to get the engine real cheap.

Hey, you can't choose your blood relatives, or predict their actions. I've lost two project cars through trusted relatives while away at school, my favorite a fully loaded 85 GT w/perfect OE seats that only needed the engine and tranny reinstalled. It's okay, I still love'm.

[This message has been edited by Joseph Upson (edited 07-04-2007).]

And as I stated before I have no experience welding. This is the best I can do and it sucks! Oh well. I just don't know what I am doing. I've never had a class or even had somone tell me what to look for or how to move the wire ----- I thought maybe I would just try and fix what was in there before---at least I had a fun car to drive.

Okay you went with gasless so automatically your welds are going to be ugly using flux cored wire. Start with the narrowest gauge flux cored wire you can get, make sure the unit is wired properly for it.
Use the proper angle and distance.
Get a piece of scrap metal similar in thickness to what you are going to be welding on.
Then tune the wire speed by starting at about 5 or 6 on the dial, squeeze the trigger and start laying a bead, at the same time adjust the feed dial up or down in an effort to get the best sounding phizzzz that you can, the more consistent/cleaner the sound the better. You can try the low power setting first then the high if you feel the need. Flux cored wire welds messy so be patient and adjust the speed at which you move your hand as needed.

Don't for get to clean your weld periodically and be careful not to exceed the duty cycle of your unit. Practice welding on the metal itself not on top of your welds.

[This message has been edited by Joseph Upson (edited 07-05-2007).]

Any updates?????

quote Originally posted by Joseph Upson: Light weight, higher melting point, corrosion resistance and if you purchase mandrel bends, fewer welds.

All true. Keep in mind though the weld els are 8 gauge (eight). A full 4mm thick, .1570 inches. And allot cheaper.

Problem

I have been looking and none of the hardware stores have weldable elbows.
Tri state welding supply looked at me like I was crazy.

See, we don't have any natural gas here in Florida and apparently that's what they use them for.

I am looking at these items though and if I cannot get it to work where it is I may sacrifice the trunk and mount the turbo there. It's a crying shame to have a disabled IMSA in the driveway.
http://store.racing-solutions.org/turboforms.html
http://store.racing-solutions.org/bendkits.html

quote Originally posted by Hudini: All true. Keep in mind though the weld els are 8 gauge (eight). A full 4mm thick, .1570 inches. And allot cheaper.

I believe that's overkill considering the unnecessary extra weight and possible multiple butt welds that can cause turbulence resulting in hot spots like what probably lead to the ruin of his previous crossover pipe. The last time I checked the weld els were more expensive than the mandrel bent pipe and doesn't look as pretty in the end.

Not arguing with you about the weld els really. Its just one option among many. It is heavy, tough stuff for sure. The ends are beveled at 45 degrees so you get a nice V to weld in. After all, they are made for welding. I went for brute strength as it was my first attempt at a turbo manifold. My next one will include an expansion joint though.

I wish him well whichever route he takes.

quote Originally posted by Joseph Upson: The expansion joint is crucial

Where did you get the expansion joint? All I can find are the 304 SS braided type. Which do you use?

quote Originally posted by Dennis LaGrua: If you are running a turbo and if you installed a commercial kit, the crossover pipe should be made of stainless steel. You've got high heat levels in that pipe and soft mild steel doesn't hold up well. You can use mild steel everywhere else in the exhaust and it will provide some life but the croosover pipe is a demanding application. If you don't have SS there right now, you'll be fixing the leak again soon.

It might be different for Fieros, but when I researched exhaust headers/turbo headers for my Mazda, I found out that Mild steel is much better to use than stainless, as stainless is much more prone to cracking because it cant expand and contract as well as mild steel. Stainless looks better, but doesn't hold up as well. Mild steel can rust, so the solution is to have it Jet-Hot coated inside and out. (It's a ceramic coating that has a gorgeous shine.)

-M

quote Originally posted by Hudini: Where did you get the expansion joint? All I can find are the 304 SS braided type. Which do you use?

The expansion joint is the good old stock GM joint cut from an OE crossover just like the one you see in a picture above along with other stock pieces he collected from the salvage yard.

quote Originally posted by Austrian Import: It might be different for Fieros, but when I researched exhaust headers/turbo headers for my Mazda, I found out that Mild steel is much better to use than stainless, as stainless is much more prone to cracking because it cant expand and contract as well as mild steel. Stainless looks better, but doesn't hold up as well. Mild steel can rust, so the solution is to have it Jet-Hot coated inside and out. (It's a ceramic coating that has a gorgeous shine.) -M

As long as you keep expansion in mind during the designing process you shouldn't have much of a problem with cracking pipes, if you wrap it that's another story, it expands and contracts as well as mild steel however, it happens to expand more so if you don't leave room for that yes you may have problems. " Stainless looks better, but doesn't hold up as well" I have to disagree there, stainless doesn't corrode as easily and withstands more heat than mild steel so I don't know how one could conclude that it doesn't hold up as well as steel.
\
As for mild steel it is easier to weld and in my experience as long as you use 14 gauge tubing and paint it well with HT paint and keep it protected rust is not likely to be an issue. Heat wrap is where temperatures start to climb and push the tubing to its limits and increase the risk of a failure.

I just received two email responses today from two companies that sell stainless and mild steel tubing, to an inquiry I made regarding which would withstand more heat under the same conditions in a turbocharged setting; 16 gauge 304 stainless, or 14 gauge mild steel, thinking that the added thickness of the 14 gauge mild steel would dissipate more heat since there is more metal, making it equal to or better than the 16 ga stainless. Both reps replied in favor of stainless. I would still like to do a formula analysis to make sure simply because the additional metal provides additional cooling under constant conditions due to the increased heat dissipation by the added metal. It's the same principle that's in place when you overbore your cylinders too much, the reduced amount of metal does not require as much heat to warm up to a particular temp and you end up adding heat faster than it is being dissipated on the water side of the cylinder leading to overheat.

Thank you for that info. I agree with you that the expansion joint is the key. Wish I had discovered that info before I built mine. Now I have to redo everything but it will be better.

Any idea where I can get the "ball joint" type pipe flare that Pontiac put on the Y-pipe where it meets the exhaust manifolds?

quote Originally posted by Hudini: Thank you for that info. I agree with you that the expansion joint is the key. Wish I had discovered that info before I built mine. Now I have to redo everything but it will be better. Any idea where I can get the "ball joint" type pipe flare that Pontiac put on the Y-pipe where it meets the exhaust manifolds?

You shouldn't need it, my current crossover has the flex joint welded into the crossover pipe which uses stock ball and socket flanges at the manifolds for connection the same way the stock "Y" pipe connects to the Fiero exhaust manifolds. In other words you can cut the "Y" pipe off a short distance from the exhaust manifold connections and weld the crossover with flex joint and turbo flange to the ends. I modified two front wheel drive front side cast iron manifolds to fit the cast iron heads including cutting one into three pieces and welding the ends on to the opposite ends of the center section and used the OE flanges from the crossover pipe that is already designed to bolt to the manifolds.

Ok, a little snooping at the u-pull-it turned up some late '80s' 2.8's and 3.1's with crossover exhaust. They had covers on the crossover so you could not see the expansion joint. I took one off and broke off the heat shields to finally reveal these.

jeffndebrus, how is your crossover coming along?

I've had limited time and limited funds as of late. I have been helping a friend do an engine swap 4.9/5spd in his GT.

So, I resorted to welding back together what was in the car when I bought it. I know it isn't a good design for flow etc etc, however, with the equipment I have, it would be nearly impossible to design and fabricate a perfect system.
So, I welded the crap out of what was there before. I also will cut it and weld in a nice 1.5" diameter x 6" braided expansion joint that I just received. I will be adding brackets and support to the turbo and or crossover as well to support the weight.

I'm curious if you have an external wastegate? With your setup, what stops the exhaust from just going out the y-pipe and not through the turbo?

EDIT: or is that a wastegate on the end of the y-pipe?

[This message has been edited by Hudini (edited 07-29-2007).]

NO JEFF!, it might work fine but the 6" expansion joint is too much, you will actually encourage expansion due to the area that piece covers, cut out an OE joint or drop down to the 4" version of what you have. You have to keep in mind the way your setup was designed both sides of the cross over pipe support your turbo, that expansion joint especially with that length will reduce rigidity on one side of the crossover and allow the other side to be subject to harmonic vibrations further stressing an area that has already failed once.

The OE joint tubing from GM overlaps some inside the bellows if I remember correctly. You will certainly need to make sure you have good turbo support.

[This message has been edited by Joseph Upson (edited 07-29-2007).]

quote Originally posted by Joseph Upson: The OE joint tubing from GM overlaps some inside the bellows if I remember correctly. You will certainly need to make sure you have good turbo support.

It does overlap. I just cut mine to fab my improved manifold. The OEM pipe goes all the way through the expansion joint to about 1/4" of the weld onto the other side. The other side is expanded slightly at the weld so the pipes fit inside one another. Pretty neat how they did that.

Maybe I should just give up on what was obviously one hell of a project by someone-------

Maybe wait until I can afford a 3800sc swap or a Northstar swap.

quote Originally posted by jeffndebrus: Maybe I should just give up on what was obviously one hell of a project by someone------- Maybe wait until I can afford a 3800sc swap or a Northstar swap.

You've gotta be kidding, you're on the right track, just make sure the loose ends are covered that's all. If you liked the car the way it was it's definately worth fixing.

I found a 1.5" X 4" here :
e bay item number 120141123930

would this be more appropriate?

Thanks Jeff

why don't you just buy some pipe, bends, and a flange. bring them to me with your stock setup and come back the next weekend and have a new tig welded setup that's a little better then what you have :P