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  • 2 months later...

i agree with TO4 when the car is running rich and unburnt fuel is left behind the cat becomes hotter, this also would cause carbon deposits, hence the black dots at the back of the car. This eventually leads to blockages to take place and the honey combe inside to become loose. this was with a metal cat as well.

Now for a new cat and re tune.

They have exactly the same compression ratio as R33's.

Although the actual comp ratio may be the same , the combustion chamber degign is completely different, which seems to be the only reason the neo's seem to hit a detonation threashold earlier than the r33 rb25's

I had a Metalcat installed (3") about 3 weeks ago and have noticed a bit of sluggishness the last week. I also just got 250kms out of 3/4 of a tank when usually I'll do 300km on that amount of fuel (car is dead stock power wise except for turbo back exhaust). After reading this thread, I'll keep a very close eye on this!

Edited by sl33py
  • 2 months later...

I have also just had a metalcat collapse. the car is running fine, slight loss of economy. EGT's are low ant the tune is 12:1 exactly.

this cat lasted barely a year. it rattles like buggery.

not happy jan....

Yup, low qual metal substrate cats have been known to fail in hot environments for years. Its not new.

It reared its head in the rota community first for obvious reasons.

If your going that way, a high qual one is mandatory, SMB, PWR etc etc.

  • 1 year later...

Bringing up a bit of an old thread. What are the symptoms for a collapsed cat? Will it still drive fine, but make f**k all power? Reason i ask, my car is at the shop at the momemt and we just can't get it to make power. It's like it's hit a brick wall and no matter how much boost we put in (anywhere from 14-22psi) it doesn't change the power at all. I'm going to go there tomorrow and unbolt the cat and run it with no exhaust to see what happens but i kind of want to know what to expect since it's been pissing me off all day. It's a Magic cat by the way, which i thought was ment to be a decent cat!

Edited by PM-R33

PM-R33 ,

I just gutted a "magic" cat on my R33 also. It had collapsed on the turbo side, you could just pick it looking at it, the wavy metal had slumped into each others curves.

Easiest way to check cat and whole exhaust restriction is to make an adaptor up that screws into your O2 sensor port, and measure the exhaust backpressure.

When my cat collapsed, i had 7psi BP. Gutting it got it down to 3.2psi. (on 257 rwkw big stall auto (over 300rwkw if manual est) )

Obviously you got your head back !

Gary

all this talk of metal cats... why not go back to a big capacity ceramic jobbie?

realistically you're going to lose max of 5kw (at a guess) to a big ceramic vs a metal, but you'll not melt the sucker or collapse it.

your tune may ruin the catalylic qualities pretty quickly, but it'll do the same on a metal cat too.

ceramic jobbies will do just fine.

PM-R33 ,

I just gutted a "magic" cat on my R33 also. It had collapsed on the turbo side, you could just pick it looking at it, the wavy metal had slumped into each others curves.

Easiest way to check cat and whole exhaust restriction is to make an adaptor up that screws into your O2 sensor port, and measure the exhaust backpressure.

When my cat collapsed, i had 7psi BP. Gutting it got it down to 3.2psi. (on 257 rwkw big stall auto (over 300rwkw if manual est) )

Obviously you got your head back !

Gary

I reckon thats more work than unbolting the exhaust from the front pipe (because you've gotta get a pressure sensor then :D)

PM-R33 ,

I just gutted a "magic" cat on my R33 also. It had collapsed on the turbo side, you could just pick it looking at it, the wavy metal had slumped into each others curves.

Easiest way to check cat and whole exhaust restriction is to make an adaptor up that screws into your O2 sensor port, and measure the exhaust backpressure.

When my cat collapsed, i had 7psi BP. Gutting it got it down to 3.2psi. (on 257 rwkw big stall auto (over 300rwkw if manual est) )

Obviously you got your head back !

Gary

Yeah man got the head back finally, was so looking forward to the tune and i get told its lost 200HP and is making standard skyline power :D

God i hope it's just the cat.

mine failed 2 weeks ago on the dyno

from california, metal insides all warped and distorted making a large restriction

emptied now :D

When it collapsed, what did the car actually do? Did it just lose all power and not make any more? What made you know it was the cat?

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