Cast header VS Weld?

[Mojo_stevo]

So what's the story, I hear some people say that you should go with cast at all cost because it is sturdier, and go with welded pipe only when you have to, because they heat up a warp. What's the story?

I am putting a T04B on a chevy 250, it will yeild around 400 hp. The 250 spews out some HOT exhaust gas, and once it get ported and rebuild and loaded with an offehauser 4bbl manifold it will put out more. Do I have anything to worry about? It will be so much more cost effective and easier if I get one welded instead on trying to go get one moulded and cast.

[2.2 Straight six]

i dont think there's any problems really with a welded one, thousands of people use them.

cast ones may lose out slightly to welden ones because welded ones are smooth internally, maybe cast ones are too, but i think welded piping would have the "smoothness" advantage.

if you know about welding you can even make your own one.

[Mojo_stevo]

Originally Posted by 2.2 Straight six

i dont think there's any problems really with a welded one, thousands of people use them.

cast ones may lose out slightly to welden ones because welded ones are smooth internally, maybe cast ones are too, but i think welded piping would have the "smoothness" advantage.

if you know about welding you can even make your own one.

Good lookin' out. Yea I'll design it, but have somebody else do the welding. I fugured as much, I mean so many people have them. Every body has seen that video where the mani on that Evo starts to glow because it got so hot. And that's when all the talk started.

[2.2 Straight six]

Originally Posted by Mojo_stevo

Good lookin' out. Yea I'll design it, but have somebody else do the welding. I fugured as much, I mean so many people have them. Every body has seen that video where the mani on that Evo starts to glow because it got so hot. And that's when all the talk started.

yea i have that video....

you never know, a little flew in the maifold could even be a good thing. my friend's brother works in tuning an he told me he'd never use a cast one on his cars. if you're going turbo one thing that would be good is a turbo brace/support it bolts to the engine an turbo to take stress off the manifold bolts, you dont want to damage them.

personally i wouldn't go with a cast manifold, actually im in the process of designing a touring car, maybe to run it in the BRITCAR series in the UK. im not sure if i want to go turbo or N/A it depends on the class i'd enter it into, but i'd definately have a welded maifold, probably self-made.

cast one's tend to be heavy and often the wastegate port is close to one or two of the cylinders as opposed to being in a good place for all four/however many you'd have.

the choice here is just a personal thing, probably a bit of an educated guess too, but i dont think you can polish the inside of a cast manifold easily, even if its not that rough its best to have it as smooth as possible, an a welded one is much better in that way.

[Black Lotus]

Originally Posted by Mojo_stevo

So what's the story, I hear some people say that you should go with cast at all cost because it is sturdier, and go with welded pipe only when you have to, because they heat up a warp. What's the story?

EDIT-- this is a brand specific example--Cheers...Brian--EDIT
My turbo car has a cast iron tri-Y header stock from the factory. The entire weight of the turbo is held up by the manifold. People have tried welding up stainless tube type manifolds, but the pipes get so hot that they lose strength and come apart or sag. So in this case everybody, and I mean everybody (except for some rich crazies in Thailand ), have reverted back to the cast manifold because it is stronger.
Nobody complains about the performance of the stock cast manifold, as it is excellent, but because it cracks after 80K miles or so and is expensive to replace ($1K).

[2.2 Straight six]

the reason you have the "turbo braces" is to take the weight of the turbo and some of the weight of the manifold off the bolts that hold the naifold to the block, therefore the manifold wont sag.

still, personally i dont think they all sag, in fact i know they all dont. because i've seen race-proven ones. many times. if cast ones were the best dont you think all the top performance cars would use them ? like the HKS drag R33.

im not criticising or saying you're wrong, this is just my opinon.

[Black Lotus]

Originally Posted by 2.2 Straight six

the reason you have the "turbo braces" is to take the weight of the turbo and some of the weight of the manifold off the bolts that hold the naifold to the block, therefore the manifold wont sag.

still, personally i dont think they all sag, in fact i know they all dont. because i've seen race-proven ones. many times. if cast ones were the best dont you think all the top performance cars would use them ? like the HKS drag R33.

im not criticising or saying you're wrong, this is just my opinon.

Are you referring to my post?
Remember that I had edited it to say that it was for a particular marque only. My other car, with an aftermarket turbo kit has stainless pipes with a brace attached to the transmission, and it works perfect. I was only implying that you had to take stainless' structural weakness under high temps under consideration. As an aside, I will be vacationing in Thailand early next year, and hope to have a first hand look at those stainless steel headers that I referred to-- for a possible purchase...:0

[Mojo_stevo]

Originally Posted by 2.2 Straight six

you never know, a little flew in the maifold could even be a good thing.

Yea lol, good way to get some of that carbon out.

[2.2 Straight six]

Originally Posted by 2.2 Straight six

you never know, a little flew in the maifold could even be a good thing.

Originally Posted by mojo_stevo

Yea lol, good way to get some of that carbon out.

how you managed to make any sense of what i said amazes me, i have no idea what i meant in that sentence. "flew" im not sure, but i think i meant "flow".

[Mojo_stevo]

Originally Posted by 2.2 Straight six

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how you managed to make any sense of what i said amazes me, i have no idea what i meant in that sentence. "flew" im not sure, but i think i meant "flow".

Bwaahahahahaha, I though you meant flew, like in a chiminey, so I thought who where refering to the hot red heating process as a form of cleaning ROFL!!!