My cats used 8 of their 9 lives.

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LSchicago

LSchicago

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Forget the ET, what did your MPH do?
MPH last time out was 138 letting out early. This time with a 3.5" pulley instead of 4" I had last time. I only hit 127MPH max, and as low as 121. My car did 121 with just an E85 tune. Definitely not just the DA. Might've lost a couple tenths, but not 15 tenths.
 

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MPH last time out was 138 letting out early. This time with a 3.5" pulley instead of 4" I had last time. I only hit 127MPH max, and as low as 121. My car did 121 with just an E85 tune. Definitely not just the DA. Might've lost a couple tenths, but not 15 tenths.
Yeah. That’s like a 150-165hp loss….
 

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The standard ceramic/precious metals gut will clog, break apart or actually melt due to but not limited to: improper fuel mixture, incorrect timing, malfunctioning oxygen sensors, unburnt fuel making its way into the exhaust, defective fuel injectors, etc. Any such event as noted above IF prolonged where the cat core is exceeding max thermal temps, can or will cause long term affects leading up to a failure.

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I see mention of the S550 GT500 catalytic converters - are they metallic spiral spun guts? If so those type of cats have been available from the aftermarket for a few years now, before the S550 came into existence and were usually recommended for turbo/supercharger applications.
 


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Every 2 years in my state. I'm very mechanically inclined, but only do simple things these days. Under car stuff is usually done by a shop I trust.
Do they do visual inspection or just OBD scanning?
The reason I ask and I know it’s easier said then done but…. Could you switch to catless LTH’s and just put the cats in for testing or even just the factory headers? I know it wouldn’t be cost effective in some regards but sure beats hampering performance or clogging cats. Just trying to think outside the box for you.
 
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Yeah. That’s like a 150-165hp loss….
That's true on a 300-500HP car. After 11 seconds it takes a lot more than 10HP to gain a tenth. That's at least a 300HP difference between 11.1 and 9.6
 
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Do they do visual inspection or just OBD scanning?
The reason I ask and I know it’s easier said then done but…. Could you switch to catless LTH’s and just put the cats in for testing or even just the factory headers? I know it wouldn’t be cost effective in some regards but sure beats hampering performance or clogging cats. Just trying to think outside the box for you.
No visual in IL. Some guys run no cats and pass. I didn't want to, but can't replace cats every 1,000 miles either.
 

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That's true on a 300-500HP car. After 11 seconds it takes a lot more than 10HP to gain a tenth. That's at least a 300HP difference between 11.1 and 9.6
Measure HP with MPH/weight. Not ET.

Too many variables with ET. You’d be trapping 20mph slower with a 300hp loss. You lost about 10mph.
 

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The metallic spiral internals are a cheaper way to make a car converter. If it were more durable and cheaper then I believe all oems would do it that way. I highly doubt the gt500 cats are made that way.
 
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Measure HP with MPH/weight. Not ET.

Too many variables with ET. You’d be trapping 20mph slower with a 300hp loss. You lost about 10mph.
Actually a good 20mph. The 138 run was cut short (and on a half inch larger pulley) I could see on the draggy where mph went down before crossing. It was a 140mph run before no doubt. The slowest pass yesterday was only 121 (Equal to my E85 tune only pass)My car as it sits with good cats with the 3.5" pulley should now trap 145, but averaged about 125 instead.

On Edit: Using a HP/MPH calculator, a 4,100 car with 550RW calculates to what I ran yesterday 125.XXmph, compared to the 850RW it should be putting down to run [email protected] That's a huge power cut.
 

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Actually a good 20mph. The 138 run was cut short (and on a half inch larger pulley) I could see on the draggy where mph went down before crossing. It was a 140mph run before no doubt. The slowest pass yesterday was only 121 (Equal to my E85 tune only pass)My car as it sits with good cats with the 3.5" pulley should now trap 145, but averaged about 125 instead.

On Edit: Using a HP/MPH calculator, a 4,100 car with 550RW calculates to what I ran yesterday 125.XXmph, compared to the 850RW it should be putting down to run [email protected] That's a huge power cut.
Ok. Yeah. That’s huge. So do you know if it’s actually your cats that’s causing this?
 
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LSchicago

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Ok. Yeah. That’s huge. So do you know if it’s actually your cats that’s causing this?
Not 100%, but they get hot REAL QUICK. I'll look at the log tomorrow.
 

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The metallic spiral internals are a cheaper way to make a car converter. If it were more durable and cheaper then I believe all oems would do it that way. I highly doubt the gt500 cats are made that way.
Mike, in regards to the metal substrate cats the best are furnace brazed and the cheaper units are wound and swaged. I’ve seen a few HJS hanging right off the turbo and survive with proper tuning. (Tri-wound, furnace brazed to a mantle w/welded Conc. or offset ends.
Europipe is an amazing system that uses HJS but we’re talking $5,000 turbo exhaust systems.
Nothing beats the longevity of OEM ceramic cats when treated with care.
 
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