My custom Metal Substrate High Flow Cat project
05-05-05 | 09:45 AM
#52
BNR built motor and twins
Joined: May 2003
Posts: 1,235
Likes: 1
From: 2 hours drive from sanity
I think I'm going to go this route myself. I've got to make sure I can pass emissions first (without the air pump). Hopefully I can just lean her out enough with this cat and be ok.
05-05-05 | 01:36 PM
#53
WWFSMD
Joined: Jun 2001
Posts: 5,035
Likes: 4
From: SoCal
Originally Posted by alberto_mg
yes, there should be enough room to install a resonator in the mid-pipe along with the cat. the cat is actually pretty short - 9" tip to tip and you could probably chop off 1" on each side if you wanted to. if you plan on doing that, you might need to mount the cat closer to the front of the midpipe around where it bends and the resonator toward the rear of the midpipe. we'll see what max comes up with 
Originally Posted by alberto_mg
looking forward to seeing max's dyno sheet
-Max
05-05-05 | 07:13 PM
#54
Import Connoisseur
Joined: Oct 2003
Posts: 1,335
Likes: 1
From: All over the place
here are some emissions results from another metal substrate cat:
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/just-smogged-car-new-high-flow-metal-substrate-cat-422978/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/just-smogged-car-new-high-flow-metal-substrate-cat-422978/
05-20-05 | 04:25 PM
#57
Thread Starter
Rotary Freak
Joined: Aug 2002
Posts: 2,690
Likes: 0
From: nyc+li, ny
just an fyi - i'm having some motor issues so i don't think this is going to hit the dyno or smog soon.
Some people have asked about noise levels and such so I'll add my impressions of overall affect on sound and noise levels.
Sound:
My impresssions sitting inside the car after it was installed is that it sounds quieter *in the cabin*. It sounds as if the exhaust sound and loudness now comes from the tailpipe rather than being all around you. I had a similar experience when I wrapped my downpipe in header wrap where it quieted the noise from the front and seemed to shift it to the rear of the car from the tailpipe.
Comparing this to a piston engine situation, it reminded of when I installed a header on one of my old VWs and I could now hear more engine noise from in front of me rather than hearing exhaust noise from the tailpipe. Except by adding the cat I got the reverse effect.
Exhaust Note:
Adding the cat alone, did not change my exhaust *note* but it did seem to decrease overall loudness from a volume standpoint slightly. Think of it as volume on 9 instead of 10.
No more fumes!
More importantly, it killed the damn fumes which made me happy and stopped my woman from complaining
Some people have asked about noise levels and such so I'll add my impressions of overall affect on sound and noise levels.
Sound:
My impresssions sitting inside the car after it was installed is that it sounds quieter *in the cabin*. It sounds as if the exhaust sound and loudness now comes from the tailpipe rather than being all around you. I had a similar experience when I wrapped my downpipe in header wrap where it quieted the noise from the front and seemed to shift it to the rear of the car from the tailpipe.
Comparing this to a piston engine situation, it reminded of when I installed a header on one of my old VWs and I could now hear more engine noise from in front of me rather than hearing exhaust noise from the tailpipe. Except by adding the cat I got the reverse effect.
Exhaust Note:
Adding the cat alone, did not change my exhaust *note* but it did seem to decrease overall loudness from a volume standpoint slightly. Think of it as volume on 9 instead of 10.
No more fumes!
More importantly, it killed the damn fumes which made me happy and stopped my woman from complaining
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