ok...so the performance of my max has been down lately...and it's winter here in Chicago...so no tracks are open for me to confirm this. But I have run friends that I USED to be able to pull on....and now THEY pull on ME......I checked my compression and posted my results last week...no problems there...and I've checked pretty much everything else. I now suspect that my cat is clogged becuase my exhaust is NOTICABLY quieter than it used to be....I have an A'PEXi cat-back and cattman y-pipe...and my exhaust is basically stock sounding now....I'm thinking about gutting my cat until I get the funds to buy myself an R/T unit....anyone have experience with gutting the cat...does it make the exhaust smell like cr@p???? Any other side effects besides not being emmission legal???

 

would a clogged cat make the car quieter?
it could be that you just got used to the noise,

A hollow cat would definately increase noise, I heard that you can loose low end with it as well? or was it with a straight pipe w/ no cat?

Why don't you get a Carsound high flow cat.. I think Warpspeed sells them, they are cheap too, like 120$ or even less... and i believe emissions remain the same.

A test I heard DBM mention is, get under your car and bang on the cat, if there is a noise like something is ratteling inside, the cat is probably f-ed.
how much miles are on the car?

 

nope...listened to it next to a STOCK 4th gen tonight....it's almost IDENTICAL now....used to be a good bit louder...

As for losing low end...I haven't lost low end with any mod so far...low end is NOT my problem at all...it's my pull from 4500 up....my car has mad low end torque. I would get a hi-flow cat...but I really don't have ANY $$$ to spend...I have a $2200 quaife + tranny rebuild to pay off....so no mods for a while.

 

gut it, it will smell a little. but there ARE NO GAINS WITH A HIGH FLOW CAT. you will at least see gains with this.

 

straight pipe

 

A clogged cat will make your exaust very smooth flowing. Like a hush without any evidence of individual cylinders firing. Just smooth steady flow of air out the exaust pipe.

You should be able to hear and "feel" your cars exaust flow, even at idle.

Put a piece of paper losely in front of the exaust pipe. It should shudder as the exaust exits. If it only moves like smooth air is pushing it away, chances are your cat is clogged.

This was a major problem with early 80's GM cars with cats that were filled with little pebble like material. The material would melt together and clog the car. Todays cars use metals in the cats to convert the exaust gases. They normally don't clog.

 

STRAIGHT PIPE?

 

I gutted my cat. I noticed no difference on & off the bottle in hp wise. Mine doesnt make any funny oder at all, but it does sound funny... but i come to expect that from a hollowed out cat. If anything, get a test pipe, its better then a hollowed out cat. The exhaust flows smoother in a straight pipe vs hollowed out cat. The exhaust will hafe more turbulance in a hollowed out cat due to its shape. KNow what i mean? Best thing to do it drop the cat out. If anything, hollow that out for now.

 

Brian I told you not to put those V-Tech stickers on your car. They only make your car slower

 

hey at least I don't call my girlfriend "mommy" when she gives me head....

 

I like those cordless phones too...

 

 

VTEC = Honda
V-TECH = Brand of Cordless Phone

 

you stole my answer

 

VTECH = Greatest University in the world

 

There are 2 ways to test for a clogged or non working cat, the easist would be to simply take it off and stick a light up to one end and look through the other. You should be able to see light. The second way would be to use a temperature gage, one of those new wireless sensor type and take a reading before and after the cat, I believe if it is hotter after, it is working, if the same not.

All the converters I have seen on the Maxima's use a ceramic brick style catalyst but it looks as though the new 2002 may use a metallic substrate type.

We talked with several tech people from the different converter manufacturer's over the last month. I had seen several converters advertised as super flow and ultra high flow (Random) and asked how they could flow so much and still pass emissions. This is what they told me:
They said all converters either standard or high flow, if EPA and CARB approved can only flow so much, if they flow more they don't pass and are not certified, they are sized by weight of the vehicle. I asked about a couple of specific 2-1/2" converters, one was about 5" wide and the other about 6" and a little longer than the other, both were high flow converters. They said no matter the body size if they are a high flow converter of the same inlet and outlet size they will all flow the same. I said what about the engine pulse theory, they said they will all flow the same or they will not be EPA or CARB approved.

That is why we don't sell or use the Random.

Dallas

WarpSpeed Performance

 

It's decided.....I'm gutting the sucker

I'll buy a new cat when emmissions test time comes around again...

 

straight pipe will give you better gains

 

 

that's what i like to hear man.

 

Here's an idea.......why don't you DYNO your car? If you really think it's that weak, then dyno it. When you drive your car all the time, it will start to feel slow. I doubt there's a single thing wrong with your car. A clogged cat will cause a loss of power at ALL RPMS, not just up top. I've never heard of a clogged cat on a 4th gen yet. If your cat is clogged, then you've got some other serious problems. Oil seems to be the major culprit of clogged cats and after your compression test, I don't think you're having any problems. Big deal if some of these cars you use to beat are now beating you. There are WAY TOO MANY VARIBLES when you're street racing. Maybe their cars were heat soaked when you ran them, maybe they had more weight at the time, maybe they were running less mods, maybe they became better drivers, maybe this maybe that. Take it to the track/dyno where you can get some hard numbers. Don't gut your cat. There's no power to be found. Everyone in here says there's power in gutting their cat, but oddly, I've never seen one dyno or timeslip to justify ANY power increase. Period.



Dave

 

notice where he says he doesn't have $120 to spend on a new hi-flow cat? I doubt he has the money to go out and dyno the car. Also, he doesn't have a baseline for his car to start with...

here, listen to someone much smarter than me:

 

If I had the money to dyno it I would....believe me.

It's just one car that I could beat before...and now he walks me HARD. neither of us have any more or less weight, more or less mods. It was like one day I could pull on him...next day he's walking me like I'm not moving. All from a roll.....hell...my buddy in his BONE STOCK 95 prelude (non-V-TEC) 135hp can hang with me pretty good now.

My car is offically slow.

Tracks are closed for the winter here...so that's a no go.

 

so gut the cat already.

 

I gotta do this christmas thing with the family first......maybe tomorrow when I get bored in the afternoon....

 

good man.

 

For anyone that has any background in the automotive industry & physics, this is incorrect. The length of the exhaust and components determines the torque and horsepower curves throughout the engine speeds. Put in a longer-length cat with a proper design and you will see low end gains but at the expense of mid and high end power. Design a cat to be shorter and you sacrifice low end exhaust velocity for more mid and high end power.

When a shorter piping is used the exhaust gas velocity is increased, allowing more flow at mid and upper RPMs. Race cars and such use dump pipes at the side sills rather than run the whole exhaust to the rear bumper. Those little Mazda RX3s and their loud rotaries w/ 10,000 rpm limits at the track?? Most of them run the short exhausts because they keep their engine speeds above 5000 rpm. They have *no* low end power but they don't need it since they launch at 6000+ RPM and stay in the mid and high RPMs after each shift.

 

Whats the difference between an Unorthadox Racing cat and a gutted one?

SuDZ

 

UR makes cats??...

 

then make p u s s y mods for maxima's.. so i guess you could say they make cats

 

you trying to change this into a UDP thread?

 

why did you say that word.. now Medic, EJ, and Dave will be in here and this will be a 5 pager

 

Someone say UDP? I've got two!!!

 

Hey Brian let me know what you want to do about your cat? Because the day you remove your car, I can do you short throw shifter. In order to get the short throw shifter you must remove the cat.