no cat and no resonator

[gogg]

My friend told me that if I gut my catalitic converter and remove my resonator that it will affect my valve seals and spark plugs (in a bad way). Is this true? :help

[Ubernoober]

Stop listening to his advice or get a second more informed friend.

In other words, no.

But why do you feel the need to make your car obnoxiously loud and polluting? You would be lucky to gain 5HP from doing that.

[RedHatchback]

Gut'n the catalitic converter? Thats the stupidest thing I've ever heard. Some guy in a riced to hell Altima down the street did that to his cat and it makes this annoying buzzing sound. He thinks its the coolest thing and he claims an astonishing 17 horsepower increase. Yeah,right. Damn ricers

[gogg]

Actually my catalitic converter was clogged.

[gumby]

from what ive read the ka engine requires a certain amount of backpressure to run properly. gutting the cat and resonator might cost you low end torque and contribute to a few issues i dont quite understand. depends on how old your car is. if its on its last legs why not or you can order a catco direct fit for $99.

screw the resonator

[scruffy63]

well I have an after market muffler and a gutted cat and no resonator. and I do feel the loss of torque but I also feel the top end gain.and I think it was worth it.plus I have a spare cat for emissions.what would be the difference between getting larger exhausts pipes or doing this. which set up would have less back pressure?

[gogg]

Soooo, would I be ok with no cat, but the resonator still in place?

[Bigrolla]

i got a question, what about cat and no resonator with aftermarket muffler?

[gumby]

no i mean get rid of the resonator its just a silencer like an extra muffler.

too little pressure with a large diameter pipe at low rpm impedes evacuation of the gases. to much pressure with a smaller diameter pipe at high rpm also impedes evacuation. it depends on how much gas is being moved at a time. its a trade off. .

the environmentally accepted normally aspirated medium seems to be a hi flow cat with 2.25" mandrel bent exhaust with a good quality muffler and no resonator.

[Ligouri Rd]

Currently I am running with gutted cats and have actually seen a loss in power. Granted that I haven't dynoed the car, but back in May I ran a 15.6et with all the cats ('96s have two) and that was without really heating up the tyres. Just last weekend I my best was a 16.03, even with big smoky burnouts and powershifting (sort of, still used a tiny little bit of clutch). The track temperature was 60ish both times and about the same humidity. There is definitely a loss in torque and I don't think that the slight gain in high end was worth it. The increase in noise was negligible (Apexi N1) but you now can actually hear the valves at low throttle, doesn't sound good to me. I heard somewhere that the exhaust manifold cannot "scavenge" the exhaust flow properly without the restriction of the cats...someone please chime in here and give a more detailed explanation.

Next week I will probably put the primary cat back in (I had an extra that I gutted). I will have to see how it runs without the secondary cat, the one that all you pre 96 guys call a resonator. I'm sure it will make more of a difference when I decide to go to forced aspiration.

[Ubernoober]

Its not the scavenging effect so much as the loss of accuracy of the O2 sensor. A small amount of backpressure is what it was designed and tuned to, so without a re-tune you tend to lose power. This is true of all modern EFI systems to some degree.

Also, polluting just because you can is not cool. It is for that reason we have insane and cruel smog laws. If people were more concious of their responsibilities we wouldn't have to be regulated right down to where we are allowed to pee.

[llamabeta]

Blame the car companies years ago for not caring about emissions. If this policy was started decades ago it wouldnt be so bad. The cars of then screwed it up. Now everyone pays the price. Hindsight is 20/20 though.

[Bigrolla]

ive alwaqys heard that s13 cats atleast flowed very well

[maik21]

well, i dont have cat and a replace my stock muffler by a muffler like a pipe. and it kill the loud sound. i noticed by an increase of power near the red zone. before i remove my muffler, i race with sentra (i think that have near to 110hp) and i take advantage by a little. very very little. near to 100kmph (60mph) .... after doing that, my car accererate and response more in all the rpms.... before, my car only acelerate into the 3000rmp, and upper the 3000, its seems to sound greate, but it not acelerate . =) i dont know how much power or torque i gain, but now, its more response.

[gogg]

If your running with no cat wont the car put out a little black smoke at higher rpms? Or is this all the cat dust being blown out?

[maik21]

yep, when i press gas to floor, it put out a little black smoke, but only a little. =) but it run better without cat. it has big response in all the line of rpms. it still acelerate and past 60mph, it still acererate very well... when i have cat and muffler, it was hard to go to 120mph, but, now, its very quick =)