Pics of my custom manifold
Originally Posted by t-von
What would happen if I used mild steel for my runners when my flange is stainless?
They aren't "incompatible" to weld like aluminum and steel. My downpipe is stainless with 2 mild steel flanges. One flange (v-band) was TIGed, the other (2 bolt) was MIGed. I'm sure someome will comment about different expansion rates between different grades of steel. It shouldn't be a problem with your flange/runners situation.
Banned. I got OWNED!!!
Joined: Aug 2002
Posts: 4,666
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From: chatsworth,Ca.
Originally Posted by Zero R
Mild steel is fine it will hold up just fine. It doesn't have the expansion rate stainless has giving it much less chance to crack if welded poorly. I'm not sure where you guys are getting mild is not good enough, unless your thinking thinwall tubing. 321 over 304 is not worth the money both are almost equal in their ability for heat at around 1600 degress. And if welded properly 304 will be fine. Unless it's for bragging rights. The benifits you get with a stainless manifold are lighter weight, and it wont corrode as easily, especially after heat cycling. Saying a manifold wont hold up because it's mild steel is just wrong. They usually will outlast the poorly welded stainless ones.
With the right weldor, mig welding is plenty strong but not ideal. Welding it up with a little buzz box is not going to work too well. The biggest problem with mig over tig is it starts the weld cold. That is usually where you will have penetration issues(there are ways around that) The other issues are the gun is more of pain to get in small spots also blocking your view, and you do not have a precise control over heat. It's kind like a hose you squirt and go. With all that said tig is a superior form of welding allowing you to control heat better, but it doesn't guarantee it produces stronger welds.
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With the right weldor, mig welding is plenty strong but not ideal. Welding it up with a little buzz box is not going to work too well. The biggest problem with mig over tig is it starts the weld cold. That is usually where you will have penetration issues(there are ways around that) The other issues are the gun is more of pain to get in small spots also blocking your view, and you do not have a precise control over heat. It's kind like a hose you squirt and go. With all that said tig is a superior form of welding allowing you to control heat better, but it doesn't guarantee it produces stronger welds.
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the opnly thing i would like to add is to also purge weld the manifold while you at it... and a couple turbo braces// gussets those never hurt either...
the manifold this guy built is functional but the question is the way it was made how long will it last? i would say with some support bracing and moderate street driving(so it dosnt build too much heat in the manifold) it should work fine....
GT4088R
Joined: Jan 2006
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From: UK
I personally like mild steel when it comes to manifolds, stainless is a right PITA to machine and cut and you get hot spots as the heat tends to stay in one place. Mild spreads the heat to the rest of the manifold so in theory it will cool better but it does fatigue easier as already said.
I have a mate that works in the ship yards and they all use Big mig welders for making ships, aslong as you can get the current high enough for the penetration then it'll be the same strength as TIG, you just need to heat it up with the gas torch.
Or you could just gas weld it and get the best of both worlds
I have a mate that works in the ship yards and they all use Big mig welders for making ships, aslong as you can get the current high enough for the penetration then it'll be the same strength as TIG, you just need to heat it up with the gas torch.
Or you could just gas weld it and get the best of both worlds
T-von Mild to stainless is fine. No worries. Stick welding is fun has a whole different feel to it.
Use schedule 10 or even 40 mild steel pipe. It will weigh a lot, but it will last forever. I agree on the ship building. A friend of mine who owns a steel place welds 1" thick plate with a mig. It's all in the machine you use and your level of experience.
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Use schedule 10 or even 40 mild steel pipe. It will weigh a lot, but it will last forever. I agree on the ship building. A friend of mine who owns a steel place welds 1" thick plate with a mig. It's all in the machine you use and your level of experience.
-S-
Last edited by Zero R; Mar 26, 2006 at 11:46 AM.
Senior Member
Joined: Oct 2002
Posts: 685
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From: Portland, OR
Oxidation
Originally Posted by Zero R
There is absolutely nothing wrong with a mild steel manifold.
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I had a custom built mild steel manifold made from mandrel bent 1/8" wall tubing with 1/2" mild flanges (mig welded). I had it in service for 3yrs with no problems with associated with cracking or warping, in this respect it was a very good manifold for $50 of materials.
However I had huge oxidation issues that caused me to replace the manifold. Not only did the outside constantly shed thin layers (similar to slag from torching) but the ~1 inch square 1/8" thick divided section preceeding the divided T4 flange completely disenegrated! Yes this section erroded to nothing!
I have since built a stainless one with no such issue (and I plan to test my modified SSAC you have seen in this section).
I am not writing off mild manifolds, just posting the facts.
Justin
Thread Starter
I brake boost
Joined: Aug 2003
Posts: 2,128
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From: Orlando
Originally Posted by kabooski
when are ya dropping the motor in Rey?
want to see how the engine bay looks with the manifold
and that big boy turbo
want to see how the engine bay looks with the manifold
and that big boy turbo
Laying Down Rotary Law
Joined: Mar 2001
Posts: 2,075
Likes: 1
From: central florida
Originally Posted by FD Rey
Well you know how long the engine is taking. lol The port job is done, just gotta get it pinned. Hopefully it will be done some time in 2006. lol
Buy Hey I want to shoot to have Gaby here in 3 months for a tuning bash
Yours , Mine and Chino's 20B GT42 FC should be done by then
Laying Down Rotary Law
Joined: Mar 2001
Posts: 2,075
Likes: 1
From: central florida
Originally Posted by FD Rey
Damn Roger, 3 months?! I was hoping we could get Gaby here before May. I'm going to Europe for a month in June.
(inside joke)
Last edited by kabooski; Mar 26, 2006 at 08:22 PM.
Originally Posted by NewbernD
Your runners will get rusty and your flange won't.
You guys keep forgetting that these things can be coated for heat and rust protection. I mean as hot as our engine bays get, why would you NOT coat any thin wall manifold? There is a guy near my shop with a built 69 Camaro that runs in the high 9's in the 1/4 mile. He would let his car idle for extended periods while doing adjustments. He had some white looking coating on his headers. You could actually physically touch them without burning your hand. To me all with rust talk is nonsense with the technology available out there.
Last edited by t-von; Mar 27, 2006 at 03:18 AM.
Originally Posted by Zero R
T-von Mild to stainless is fine. No worries. Stick welding is fun has a whole different feel to it.
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Thx! Last question, which stick should I use? Stainless or the mild steel rods?
Stainless has added chromium in it to help with corrosion resistance. Mild can shed layers just as a factory cast manifold will over time. This is why you would need pipe not tubing. If you keep it coated it will last a long time and help with corrosion.
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Originally Posted by pistonsuk
I will first admit that I am pretty hard on stuff. I am heavy on the throttle and also log ~800C at cruise and up to 950C under extended boost runs.
I had a custom built mild steel manifold made from mandrel bent 1/8" wall tubing with 1/2" mild flanges (mig welded). I had it in service for 3yrs with no problems with associated with cracking or warping, in this respect it was a very good manifold for $50 of materials.
However I had huge oxidation issues that caused me to replace the manifold. Not only did the outside constantly shed thin layers (similar to slag from torching) but the ~1 inch square 1/8" thick divided section preceeding the divided T4 flange completely disenegrated! Yes this section erroded to nothing!
I have since built a stainless one with no such issue (and I plan to test my modified SSAC you have seen in this section).
I am not writing off mild manifolds, just posting the facts.
Justin
I had a custom built mild steel manifold made from mandrel bent 1/8" wall tubing with 1/2" mild flanges (mig welded). I had it in service for 3yrs with no problems with associated with cracking or warping, in this respect it was a very good manifold for $50 of materials.
However I had huge oxidation issues that caused me to replace the manifold. Not only did the outside constantly shed thin layers (similar to slag from torching) but the ~1 inch square 1/8" thick divided section preceeding the divided T4 flange completely disenegrated! Yes this section erroded to nothing!
I have since built a stainless one with no such issue (and I plan to test my modified SSAC you have seen in this section).
I am not writing off mild manifolds, just posting the facts.
Justin
The down sides to mild steel
Mild steel looses the vast majority of it's room tempurture strength by 900 deg F. An exhaust manifold on a 10sec drag pass will spend about 9 secs over that tempurture. Mild steel is very suseptable to vibration, so on that 10 sec pass you have a very soft manifold being vibrated to peices. Although the manifold may have enough strength to physicaly support the turbo it WILL crack and it will usually crack at the weld were the heat tempre of the material changes. The cracking of the manifold CAN NOT be prevented with ANY kind of coating. So you say just make it out of thicker metal. Heat transfer is directly proportional to surface area (imagine a blow torch against an infinitly think block of aluminium), now that your manifold is made of thinker material the manifold has a greater surface area and therefore transfers more heat out of the exhaust stream to the atmosphere, and it is still suseptable to the vibration of the turbo charger.
The bigest advantage to stainless steels is their ability to retain their strength at elevated tempuratures. For example Incolnel tubing retains ~100% of it's room temurature yeild strength at 1500 deg. Inconel is just higher nickle content stainless steel than 304 or 321. In there ability to retain strength at operating tempuratures they also retain their ability to vibration resistance.
For the purposes of the majority of the people on this board 304 and 321 are more than adequit. 1/2 flanges and .063" tubing will give the best comprmise of durability and performance.
But the again what do I know, it's not like I study and apply any of this crap
Mild steel looses the vast majority of it's room tempurture strength by 900 deg F. An exhaust manifold on a 10sec drag pass will spend about 9 secs over that tempurture. Mild steel is very suseptable to vibration, so on that 10 sec pass you have a very soft manifold being vibrated to peices. Although the manifold may have enough strength to physicaly support the turbo it WILL crack and it will usually crack at the weld were the heat tempre of the material changes. The cracking of the manifold CAN NOT be prevented with ANY kind of coating. So you say just make it out of thicker metal. Heat transfer is directly proportional to surface area (imagine a blow torch against an infinitly think block of aluminium), now that your manifold is made of thinker material the manifold has a greater surface area and therefore transfers more heat out of the exhaust stream to the atmosphere, and it is still suseptable to the vibration of the turbo charger.
The bigest advantage to stainless steels is their ability to retain their strength at elevated tempuratures. For example Incolnel tubing retains ~100% of it's room temurature yeild strength at 1500 deg. Inconel is just higher nickle content stainless steel than 304 or 321. In there ability to retain strength at operating tempuratures they also retain their ability to vibration resistance.
For the purposes of the majority of the people on this board 304 and 321 are more than adequit. 1/2 flanges and .063" tubing will give the best comprmise of durability and performance.
But the again what do I know, it's not like I study and apply any of this crap
^ Then again if both manifolds are coated, what difference is it going to make with heat related issues? In the end, the mild steel manifold will just be a little heavier, quieter, and cheaper. Hell overall, anything lighter than the stock **** is an improvment.
Last edited by t-von; Mar 30, 2006 at 03:56 PM.