I originally posted this on another thread, but thought i might get a better response here.

Original Thread


Got under the car today and found out my ARH cats are blown out as well. i've got a few relevant questions to post if OP doesn't mind.

1. I can't find any remains of the pass side substrate. I inspected from the header/Xpipe collar to where the 3" mid-pipes neck down to 2.5" at the axleback. The only evidence that a substrate was even there was this little bit of metal on the O2 sensor. Judging from the pics on this thread, can I assume that there is a lump of substrate material lodged somewhere in the overaxle pipe or muffler? If so, any suggestion on how to clean it out? God forbid it went the other way...



2. The driver's side O2 sensor was damaged in the blowout. Should I replace? What would cause the sensor to bend like that? Was it the force of the substrate hitting it, or was it a combination of heat and force? I tried to bend the sensor back and it is pretty sturdy, which leads me to believe that the metal was softened by excessive heat. The reason I ask is because, obviously, both side were subject to similar intense heat, and I wonder if both sensors were damaged by that heat. I realize that the sensor must be heated to work properly (I've seen posted anywhere from 300*-650*,) but I wonder if the temps were hot enough to destroy the substrate, would they be hot enough to damage the sensors as well?





3. The phrase is "I blew out my cats," and this is true in that I was driving at the time. I've got 700 hp and am often in boost (although rarely for long (2-3 seconds,) or full pressure (14 lbs.) If there is some part of my driving that is wrong, I'd like to correct it. I assumed that being "hi-flow", the parts were designed to handle the heat and pressure of high horsepower. If "I" blew out my converters, I'd like to change that habit. If it's just a matter of catalytic converters =/= high horsepower, then I won't worry about it.

OP, thanks for letting me jump your thread.

 

Looking at the top picture, it kinda looks like the torch that the statue of liberty is holding...

 

I don't think its your driving. Sounds like your cats just let go. I wonder if it might be the mfg'ing of the cats. I don't know for sure I'm just throwing out ideas. I'm sure others will chime in.

 

Any feedback from the ARH manufacturer? I'd call them up and see what they have seen, and if they will replace the cat section as faulty.

 

How rich is your car under boost?

I would imagine that your cats are in your mufflers. What type of mufflers do you have? Bullets should just let them pass through, as would NPP style in the open position. Other styles may be hard. Have you crawled under the car and hit the mufflers with your hand to see if they rattle?

Take them and start dumping one side then the other.

DJ

 

I wouldn't necessarily assume that they're responsible in a situation such as this, it's essentially a racing part and there are many other possible factors other than manufacturer's defect that can contribute to that happening. If something like this happened within just a few weeks/miles of install then it certainly is possible that they were defective.
Generally speaking, catalytic converters and forced induction/nitrous (or even just a very serious NA set up) simply don't get along well.

 

Thanks guys. I pulled the (stock, non-NPP) muffler and ran a coat hanger through the over axle - no blockage, and no rattling sounds in the can. This surprises me based on the plumbing of the muffler (two separate pipes in and out.) The substrate must have burnt to a crisp and blown through the mid pipe and over axle, through the chambers of the muffler, and out the tip in little pieces. Amazing!

I'm not a tuner, but this whole matter was started when I tried to get the car past emissions. local test is a tailpipe test at idle and at 2k rpm. and it was blowing really high for CO with the ARH cats. i assume this to be a rich air fuel ratio. i've ordered an EFI tuner and will work with a professional to get it right.

Although the exhaust only has 1500 miles on it, I purposefully tried not to suggest that i thought there was anything wrong with the product or installation in my original post. i'm no engineer, but now i feel that it was just kind of stupid on my part to bother with cats on a high HP FI car. I should have just gone with a non catted xpipe. Ill call the manufacturer and see if they'll do anything for me.

 

Under boost the afr will be rich. Not the first time I've heard of this happening.

You would get more answers over in the FI section.