Soul certainly has dyno charts on GT4 Long-tube catted Street headers, right on the page where the headers are shown. Comparison runs of stock, stock with tune, catted headers with tune, and catless headers with tune.

 

Yeah, my mistake for posting in the GT4 forum.

You probably read this part too though right?

 

I did; just pointing out that the dyno charts for the 3.8 should give you some reasonable assumptions about the 3.4 to help in making your decision. Didn't know if you had seen that they were posted on the GT4 headers, as you might have just not clicked on it once you saw it was the wrong product for your needs.

 

Hats off to JC and John for the great posts. I have had Cargraphic sport headers on my car for six years and over 100 track days in Texas. Not one glitch at all. They just keep on going. I suspect they will wear out one day, and I will get a CEL, but I have had six years of great service out of these headers. I do take care of my car though. The Cayman S has a third radiator on it and I usually add a few gallons of 109 octane race gas to blend my octane rating up to 95-96. I am not looking for extra power from the race gas, just want to keep the engine happy.

 

I just had my Cargraphic sport headers crack at the track. Anyone had this happen before?

 

Are those the earlier generation Cargrahic Sport headers that do not have the additional bracing that stabilizes the catalytic converter to the cylinder head and header pipe?

 

Is that for strength bracing or vibration/resonance damping?

 

Yea these are the older ones. I'm guessing between the heat and flexing it was too much stress

 

Looks like it failed in the heat affected zone in the weld. If so it's most likely inter granular corrosion attack. That's why Dundon uses 321 SS. 321 is not affected by this problem.

 

The entire exhaust system on 981 cars moves with the engine/transmission assembly, by design and mounting. Due to the modular design of the Cargraphic sport headers to allow removal of the cats and installation of the bypass pipe, there is a joint where the clamp is by the crack shown in the photo. Without the bracing used in the newer generation of Cargraphic sport headers, the next support for the cat and exhaust pipes after the end of the header collector is where the muffler hangs from the support frame that is mounted to the aft end of the gearbox. As I recall from some BGB Motorsports postings a few years ago, a track car that was aggressively using curbs for a while developed cracks in this area. That's why the bracing was added. Go look at photos on Cargraphic's or BGB's website and you can see the bracing that's used now.

Flexing yes, not aware of any of the newer braced versions cracking in this area. I would go back to who you bought them from and show them what's happened, or go direct to Cargraphic.

Seems like that would take some metallurgical analysis to determine if this is inter-granular corrosion attack as you postulated. Does Dundon offer a modular header that allows removal of the cats to install a bypass pipe? If not, I don't think there is any way to know if a Dundon header would or would not experience a similar issue if not braced like the newer Cargraphic.

 

Yea I emailed Cargraphic and they're helping me out. Customer service is great over there.

 

I spent my career working for AK Steel in their Research Group and Customer Specialty Stainless Technical Services. In that time I worked with every major exhaust manufacturer in the US and several European manufactures. True, a weld cross section would 100% confirm the presence of chrome carbides in the HAZ. But I've seen enough of these failures to put my money on IGA.

 

Makes one wonder if any of the newer generation braced Cargraphic sport headers have experienced a crack and failure in this same area. I haven't heard of any but Rennlist or Planet 9 are the only places I would have heard about it other than comments around the paddock during a track event.