F355 - What type of headers should i go for?

Daniel,

Can you provide more details about these? Thickness, type of steel, etc.?

I cut open a 1998 OEM header a few weeks ago and measured the inner tubes. Generally I was seeing 1.0-1.3mm thick which corresponds to 18 gauge metal. It would be nice to get more data as this seems to be a nice option...

 

304 stainless, 1.5mm.

Here is a picture of a finished header:

(Please note, each one will be different, depending on the ability to get the original heat shields cleanly cut with the least amount of "lost" material)
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Dave Stebb at stainless headers... Insulated in the clam shell reduced heat in engine bay..look factory
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Stainless Headers Mfg., Inc. fabricates custom headers in stainless and mild steel

 

Depends if you want the air rail... around $3200 Thats a competitive price and also take into account that they are put back into the factory clam shell ..if you go with fabspeed or others you should run header blankets these its not necessary.

 

See Jim's thread I posted above - look up a few posts

 

bare headers I think start around $2400

 

Can someone explain how, or why, 4-2-1 gives more torque but 4-1 gives more HP?

In looking at the relatively short distance between the pipes and the collectors, I'm trying to understand why there is a difference. Is it a change in back-pressure from one design to the other?

 

Sorry I can't give you the technical explanation, but it probably has to do with pulses "pulling" the exhaust out. One of my old race engine builders told me: "Horsepower sells motors, but torque wins races".

 

My personal vote would be for the 321 stainless steel headers by Stainless Headers. None of these other manufacturers are making them in 321, but are charging a hefty price tag for them (ex. tubi). 321 stainless steel is basically 304 stainless steel with some titanium in it. It is generally lighter and more durable.

Fabspeed headers are 4-1 and 40 gauge stainless steel. Thick enough to last a lifetime, hence the lifetime warranty, but heavier than a 16 guage 321 stainless steel header.

If the price is within the same ball park, I'd rather go with the 321 4-2-1 design. Keep the torque the same. Retain the F1 sound and lighten up the rear at the same time.

 

I'm also not a fan of the factory heat shields. In the case that something is wrong, it is impossible to see what is going on unless the headers and shields are removed.

I had contemplated having a local shop build me a set in pretty much the same specs Stainless Headers has them built. However, I wanted them ceramic coated only on the inside and very thoroughly. I figured I'd send them to Swain tech (White Lightning coating) in pieces, so they could be coated thoroughly on the inside. Swain Tech mentions at least .015" thick to be of any effective long-term insulating value.

White Lightning Exhaust Coatings | Swain Tech Coatings | Industrial Coatings | High Performance Racing Coatings

I am speculating and hoping coating only the inside will be effective enough to reduce adverse heat in the engine bay while protecting components such as the alternator in Inconel. This should allow the header to effectively breathe as opposed to being insulated by shields or a top layer ceramic coat. If it doesn't work, I will probably looking into a blanket. Fabspeed offers pretty nice looking ones.

 

Ken, Hytech which is located in California builds very nice headers. They would build them in 321 s/s. They built headers for Ernie's 348 in 321 s/s. The headers looked very nice.

Stainless Headers would probably prefer to build them without the shields as it is more work for them. The cost would also be ~ $650 cheaper. But keeping the OEM look as well as protecting the engine bay components was important to me that is why I retained the OEM shields.

I know some owners have coated their headers and have been happy with it. I am just not sure how evenly the coating could be applied to the inner tubing? How long it will last?
What happens if it starts coming off and if it will end up back in the motor? I don't believe anyone had boroscoped their headers prior to installation and has taken them off periodically to see how well the coating is holding up over time.

There was a thread about header coatings awhile back.