What is the purpose of the fake cat and floor indentation? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

alkemyst · 11-04-2006, 03:41 PM

Seems this causes more problems than it helps. With the cat in the downpipe, why did Nissan put in a fake one under the driver's side (USDM) and bend the floorboards to fit it?

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cmcdougle · 11-04-2006, 04:12 PM

it's not fake, it helps a lot for smog. It made a HUGE difference for my car.

alkemyst · 11-04-2006, 04:16 PM

Quote:

Originally Posted by cmcdougle

it's not fake, it helps a lot for smog. It made a HUGE difference for my car.

For that to happen it must not be hollow...I haven't popped open mine yet, just going off forums.

**Phlip** · 11-04-2006, 04:25 PM

You're in Florida, do you not know anyone well enough to inspect your car without it?

alkemyst · 11-04-2006, 04:30 PM

Quote:

Originally Posted by PHLIP

You're in Florida, do you not know anyone well enough to inspect your car without it?

Its not about my legality...just don't know what it really does.

gotta240 · 11-04-2006, 05:33 PM

oops! my mistake!

**mrmephistopheles** · 11-04-2006, 07:29 PM

on every S14 I've seen the 2nd 'cat' is hollow.
The hump is there because in Japan, a precat is impossible due to the design of the turbo manifold and downpipe.

gotta240 · 11-04-2006, 07:41 PM

i struggle to believe that the second cat is hollow on every s14....however i haven't seen otherwise so i guess i'll have to check myself!

It seems like a horrible waste of money to make something that looks and fits like a cat, just to have it be hollow. If they didn't need the cat, or were to make it hollow, i'm assuming nissan would have just extended the exhaust pipe that extra 12 inches and done away with a cat...but what the hell do i know?!

frankist · 11-04-2006, 08:15 PM

you sure its not a resonator.

cmcdougle · 11-04-2006, 08:22 PM

Last saturday, I saw a guy at a swap meet that was selling a hollow cat. I thought it was pretty cool until I looked into my exhaust on wednesday, and mine was hollow too. I had the thought cross my mind that the guy was a liar and that they were all hollow, but then my car was right on the limit for passing smog, so I figured mine was hollowed out too.

If they all are hollow, why would Cali make such a big deal about removing the cat?

!Zar! · 11-04-2006, 08:40 PM

Kevin hit the nail on the head.

Quote:

Originally Posted by cmcdougle

Last saturday, I saw a guy at a swap meet that was selling a hollow cat. I thought it was pretty cool until I looked into my exhaust on wednesday, and mine was hollow too. I had the thought cross my mind that the guy was a liar and that they were all hollow, but then my car was right on the limit for passing smog, so I figured mine was hollowed out too.
If they all are hollow, why would Cali make such a big deal about removing the cat?

Not ALL cats are hollow. Only the second cat on s14's.

articdragon192 · 11-04-2006, 09:47 PM

The dummy cat (or second cat) on an S14 is pretty much a test pipe. It's all hollowed out. makes for a cheap test pipe.

gotta240 · 11-04-2006, 09:59 PM

WHY?! Sorry to go on and on with this, but why the hell would nissan waste so much money to make a FAKE part when they could have just extended the exhaust tubing(which would cost them pennies)???

also, this means putting headers on a s14 will basically make it fail smog automatically. (i'm talking about actual measurements, not visual)

usdm180sx · 11-04-2006, 10:10 PM

With the s14 Nissan included the cat in the usdm downpipe to comply with stricter emissions laws in the US (California). Locating the cat closer to the motor allows the cat to heat up quicker and reduce emissions.

In Japan (and the rest of the world) the emissions laws are not as strict so the downpipe does not have a cat. Instead, the cat is located where the hollow usdm one is.

articdragon192 · 11-04-2006, 10:12 PM

Quote:

Originally Posted by gotta240

WHY?! Sorry to go on and on with this, but why the hell would nissan waste so much money to make a FAKE part when they could have just extended the exhaust tubing(which would cost them pennies)???

also, this means putting headers on a s14 will basically make it fail smog automatically. (i'm talking about actual measurements, not visual)

Someone failed reading. Kevin answered that question a few posts up. And an S14 with a header can pass measurements. Just put a cat where the dummy cat is.

dans · 11-05-2006, 04:32 AM

Think of it as an invitation to cut that hump out of your floorboard when you get the car so its easier to mount a decent seat in a decent position. Aside from that it made sense to Nissan to have a dummy cat as it would only have to purchase empty bodies from its cat manufacture and plug them in as if it was their SR powered car. While it may not make perfect sense to us it made good sense to them and hey, it was their dime.

alkemyst · 11-05-2006, 09:37 AM

Quote:

Originally Posted by usdmsilvia

With the s14 Nissan included the cat in the usdm downpipe to comply with stricter emissions laws in the US (California). Locating the cat closer to the motor allows the cat to heat up quicker and reduce emissions.

In Japan (and the rest of the world) the emissions laws are not as strict so the downpipe does not have a cat. Instead, the cat is located where the hollow usdm one is.

Makes sense. I wish most here would only post on things they *REALLY* know about.

I haven't opened mine, but knocking on it...it's hollow as far as I know. Everywhere else seems to back up that.

Never knew why they'd put a part in that did nothing and changed the car so much...but the overseas version makes it clear.

alkemyst · 11-05-2006, 09:40 AM

Quote:

Originally Posted by dans

Think of it as an invitation to cut that hump out of your floorboard when you get the car so its easier to mount a decent seat in a decent position. Aside from that it made sense to Nissan to have a dummy cat as it would only have to purchase empty bodies from its cat manufacture and plug them in as if it was their SR powered car. While it may not make perfect sense to us it made good sense to them and hey, it was their dime.

I am willing to bet places like california would fail you for removing it...despite it doing nothing. I don't know if they still are so picky, but my Mustang H pipe came with 2 pre cats and 2 cats from the factory. The aftermarket one I bought had two hollow 'pre cats' and two real ones. Looked similar but about 0.5 - 1" bigger in diameter. We had inspections in Florida back then.

projectRDM · 11-05-2006, 11:27 AM

I can't believe there's still confusion in this thread.

Kevin answered it directly, but to clear it up for the glue sniffers:

Redesigning the floorboard to accomodate a smaller exhaust pipe costs money. A lot. That's two different castings for one part.

Redesigning the downpipe costs money as well, especially when the 'fake' cat casting already exists. Nissan uses that part in numerous cars across the product line, it makes way more sense to use it than to build something new.

And FYI, the 'fake' cat can actually have honeycomb in it, I've gutted or stripped at least 30 cars over the years and have seen one or two that were not hollow, it depends on where it was produced (on what line) and what they had in stock during the build, whether there were leftovers from S13s or new castings without the material. There is no definite answer on that but 95% of them are hollow from what I've seen/heard.

alkemyst · 11-05-2006, 04:56 PM

Quote:

Originally Posted by cmcdougle

Last saturday, I saw a guy at a swap meet that was selling a hollow cat. I thought it was pretty cool until I looked into my exhaust on wednesday, and mine was hollow too. I had the thought cross my mind that the guy was a liar and that they were all hollow, but then my car was right on the limit for passing smog, so I figured mine was hollowed out too.

If they all are hollow, why would Cali make such a big deal about removing the cat?

Dude you realize in this very thread you said you have already replaced it and it made a HUGE difference right?

inertiaticism · 11-05-2006, 08:41 PM

Quote:

Originally Posted by R240NA

And FYI, the 'fake' cat can actually have honeycomb in it, I've gutted or stripped at least 30 cars over the years and have seen one or two that were not hollow, it depends on where it was produced (on what line) and what they had in stock during the build, whether there were leftovers from S13s or new castings without the material. There is no definite answer on that but 95% of them are hollow from what I've seen/heard.

Yeah, mine had the matrix inside of the second cat.
I wonder how much of it has to do with build date, I think mine was late summer of '94.

trsilvias13 · 11-06-2006, 12:34 PM

My 97 have the honey comb in it. I pulled mines out and put it back (thanks to CHP)

11-04-2006, 03:41 PM	#1
alkemyst Zilvia Addict Join Date: Oct 2003 Location: Florida Age: 54 Posts: 868 Trader Rating: (0) Feedback Score: 0 reviews	What is the purpose of the fake cat and floor indentation? Seems this causes more problems than it helps. With the cat in the downpipe, why did Nissan put in a fake one under the driver's side (USDM) and bend the floorboards to fit it? Å __________________ Now my Kensai, I curse you to be a Ronin and with the my remaining spirit I, beseech Chimata-No-Kami, to have you wander through time and distance lands, seeking a new master.

11-04-2006, 04:12 PM	#2
cmcdougle Zilvia FREAK! Join Date: May 2006 Location: Irvine, CA Posts: 1,361 Trader Rating: (0) Feedback Score: 0 reviews	it's not fake, it helps a lot for smog. It made a HUGE difference for my car. __________________

11-04-2006, 04:25 PM	#4
Phlip Yes, I look like that Join Date: Mar 2002 Location: In my supervillain's lair Posts: 27,980 Trader Rating: (19) Rides Gallery: Phlip Feedback Score: 19 reviews	You're in Florida, do you not know anyone well enough to inspect your car without it? __________________ Weirdo And I write too!

11-04-2006, 05:33 PM	#6
gotta240 Post Whore! Join Date: Dec 2005 Location: so cal Posts: 3,496 Trader Rating: (21) Feedback Score: 21 reviews	oops! my mistake! Last edited by gotta240; 11-04-2006 at 10:15 PM..

11-04-2006, 08:15 PM	#9
frankist Zilvia Junkie Join Date: Sep 2005 Location: socal. Posts: 411 Trader Rating: (13) Feedback Score: 13 reviews	you sure its not a resonator. __________________ ///+++

11-04-2006, 07:41 PM	#8
gotta240 Post Whore! Join Date: Dec 2005 Location: so cal Posts: 3,496 Trader Rating: (21) Feedback Score: 21 reviews	i struggle to believe that the second cat is hollow on every s14....however i haven't seen otherwise so i guess i'll have to check myself! It seems like a horrible waste of money to make something that looks and fits like a cat, just to have it be hollow. If they didn't need the cat, or were to make it hollow, i'm assuming nissan would have just extended the exhaust pipe that extra 12 inches and done away with a cat...but what the hell do i know?!

11-04-2006, 08:22 PM	#10
cmcdougle Zilvia FREAK! Join Date: May 2006 Location: Irvine, CA Posts: 1,361 Trader Rating: (0) Feedback Score: 0 reviews	Last saturday, I saw a guy at a swap meet that was selling a hollow cat. I thought it was pretty cool until I looked into my exhaust on wednesday, and mine was hollow too. I had the thought cross my mind that the guy was a liar and that they were all hollow, but then my car was right on the limit for passing smog, so I figured mine was hollowed out too. If they all are hollow, why would Cali make such a big deal about removing the cat? __________________

11-04-2006, 09:47 PM	#12
articdragon192 Post Whore! Join Date: Jan 2005 Location: West covina Age: 39 Posts: 6,792 Trader Rating: (9) Feedback Score: 9 reviews	The dummy cat (or second cat) on an S14 is pretty much a test pipe. It's all hollowed out. makes for a cheap test pipe.

11-04-2006, 09:59 PM	#13
gotta240 Post Whore! Join Date: Dec 2005 Location: so cal Posts: 3,496 Trader Rating: (21) Feedback Score: 21 reviews	WHY?! Sorry to go on and on with this, but why the hell would nissan waste so much money to make a FAKE part when they could have just extended the exhaust tubing(which would cost them pennies)??? also, this means putting headers on a s14 will basically make it fail smog automatically. (i'm talking about actual measurements, not visual)

11-04-2006, 10:10 PM	#14
usdm180sx Post Whore! Join Date: Dec 2005 Location: 562 Posts: 4,807 Trader Rating: (5) Rides Gallery: usdm180sx Feedback Score: 5 reviews	With the s14 Nissan included the cat in the usdm downpipe to comply with stricter emissions laws in the US (California). Locating the cat closer to the motor allows the cat to heat up quicker and reduce emissions. In Japan (and the rest of the world) the emissions laws are not as strict so the downpipe does not have a cat. Instead, the cat is located where the hollow usdm one is. __________________ -Norm!

11-05-2006, 04:32 AM	#16
dans Leaky Injector Join Date: Aug 2006 Location: Central Ohio Age: 54 Posts: 64 Trader Rating: (0) Feedback Score: 0 reviews	Think of it as an invitation to cut that hump out of your floorboard when you get the car so its easier to mount a decent seat in a decent position. Aside from that it made sense to Nissan to have a dummy cat as it would only have to purchase empty bodies from its cat manufacture and plug them in as if it was their SR powered car. While it may not make perfect sense to us it made good sense to them and hey, it was their dime.

11-05-2006, 11:27 AM	#19
projectRDM Post Whore! Join Date: Dec 2002 Location: Atlanta Age: 51 Posts: 13,812 Trader Rating: (12) Feedback Score: 12 reviews	I can't believe there's still confusion in this thread. Kevin answered it directly, but to clear it up for the glue sniffers: Redesigning the floorboard to accomodate a smaller exhaust pipe costs money. A lot. That's two different castings for one part. Redesigning the downpipe costs money as well, especially when the 'fake' cat casting already exists. Nissan uses that part in numerous cars across the product line, it makes way more sense to use it than to build something new. And FYI, the 'fake' cat can actually have honeycomb in it, I've gutted or stripped at least 30 cars over the years and have seen one or two that were not hollow, it depends on where it was produced (on what line) and what they had in stock during the build, whether there were leftovers from S13s or new castings without the material. There is no definite answer on that but 95% of them are hollow from what I've seen/heard.

11-06-2006, 12:34 PM	#22
trsilvias13 Nissanaholic! Join Date: Nov 2001 Posts: 1,995 Trader Rating: (5) Feedback Score: 5 reviews	My 97 have the honey comb in it. I pulled mines out and put it back (thanks to CHP)