Turbo header material/coating question

[Stoichiometric]

I have been doing some research about the methods for fabricating a set of turbo headers. I am deciding between using a set of port matched factory manifolds or building a set of tubular headers. If I were to go the tubular route, I would lean toward using mild steel and coat it with 2000+ degree coating. Would the flow benefit of going tubular outweight the longevity of the cast factory manifolds? These will go on a 408 LS1 engine with a single turbo with a HP goal around 800. Probably around 15psi of boost.

Here are the factory manifolds

[barno68]

Great minds think alike I suppose, I have been mulling this same thing over for the past few months for an LT1. I have a set of corvette cast manifolds that would be easy to cut and invert for a dual setup, I worry about the longevity of the weld for the T3/T4 flange though.

But I would think that a tubular log setup would be easy to fab up also. The flow characteristics are not as critical on a turbo setup, but it seems there would be a lot of swirl and distruption in a log design. I look forward to seeing where this thread goes.

Brent

[705.0Merc]

I have seen a turboed Ls1 put out 1200hp using the factory manifolds.
It all depends which would fit better. Making your own lets you put things where you want. I think either will get you your power goal.

[Stoichiometric]

I would prefer to build my own headers so that I can retain the factory coil brackets and spark plug wires. I am weighing the cost of materials for using stainless with coating or mild steel with coating. I might try coated mild steel and see how long it lasts, I won't be upset when they fail.

If I use the stock manifolds upside down, I'll save money and have a durable manifold. I will have to re-locate the coils, and I don't like the looks when the manifolds are pointing in random upward directions.

I appreciate the help.

[barno68]

Take a look at the for sale section, someone is selling a Banks system that looked interesting. Basically it uses a fabricated log header with the bo valve on the front end and the turbos on top and both exiting to the rear. I like the looks of the setup as it is compact and seems balanced. Many setups I have seen place the turbo off the front of the header which puts all the weight up front, just seems that is a lot of stress carried by the forward part of the heads.

Brent

[Stoichiometric]

Thanks for the heads up Brent. I checked out the add in the for sale section but the manifolds are for Gen1 SBC, the Gen3s have spread exhaust ports. That kit may be a good starting point for your LT1 if you were still thinking of adding turbos.

I have made the decision to use 304 stainless to build some tubular headers and ceramic coat them. I'll also add support brackets to hang the turbos.

[barno68]

Thanks for the heads up Brent. I checked out the add in the for sale section but the manifolds are for Gen1 SBC, the Gen3s have spread exhaust ports. That kit may be a good starting point for your LT1 if you were still thinking of adding turbos.

I have made the decision to use 304 stainless to build some tubular headers and ceramic coat them. I'll also add support brackets to hang the turbos.

Sorry about the confusion, I meant take a look at the photo's for design ideas. Your end plan is probably what I will go with at a later date. Need to get the car back together and on the road before I can justify tearing it down again :-)

[wiedemab]

Just a thought, but Jeff Schwartz might be helpful. I saw on his web site that he sells cast turbo manifolds.

http://www.schwartzperformance.com/products.htm

Might be worth a phone call. I'm not sure what your budget is. I always thought that if/when I ever built a turbo engine that I would lean toward the manifold route- for budget reasons mainly!

[INTMD8]

Coated 16 gauge mild steel will last a very long time. That being said, the stock manifolds are certainly capable of supporting your hp goals without being restrictive.

[Stoichiometric]

Sorry about the confusion, I meant take a look at the photo's for design ideas. Your end plan is probably what I will go with at a later date. Need to get the car back together and on the road before I can justify tearing it down again :-)

No worries, I appreciate the link. I like to check out everything available before I start building.

I checked out the Schwartz manifolds, they look like very nice pieces and worth a call.

I have a few options right now if I build a tubular header. I have plenty of 1 3/4" 16ga. mandrel bends to complete the headers, but they are aluminized and I am not sure how hard that will be to strip before the coating can go on. Option B is sacrificing a used set of 304ss 1 7/8" headers that are in the spare parts pile. Option C is buying new material either raw mild steel U bends or 304.

[redhead]

I don't know who you plan to use for the ceramic coating but ask
lots of questions. specifically about the ceramic in the
internal header tubes that could break loose and rattle through the
turbo's exhaust wheel. on a street engine that is not internally
inspected often this can be a problem especially if you are coating
used parts. I had a new turbine housing coated on the outside with
jethot 2000. jh did not recommend coating the housing internally.
after three or so years the exterior coating began to crack and chip
off some areas. if that had happened internally my turbo would be
toast. This is also the reason non-race turbo engines skip the
ceramics in the combustion chamber or any internal component prior
to the turbo.
da.