How to delete the Catalytic Converter - Page 3

porsche4life · porsche4life's Garage

thing is im not worried about that cause out here its all idiots with loud speakers in there lincolns not hondas...and som big pickups that are loud with straight pipes and the cops dont bother them

Brando · Brando's Garage

If you don't want to remove the catalytic converter... Remove the muffler... Then buy earplugs and get used to the reduced torque down low

flash968 · 07-12-2007, 06:12 AM

testing will be done everywhere eventually - it's all related to regionally measured particle count in the atmosphere - state by state they have been coming up to the testing standards that california has in order to meet the federal clean air act standards, which get more strict every year as a part of the plan to reach clean air - in 2009 everyone is supposed to be on the same standard

they will likely exempt anything 20 years old though

Spievy · 07-16-2007, 09:16 AM

OK, I know I posted that I like the sound of the no cat on my 944. But now I have got sick of the farting noise it makes ( I took the cat out but a 2" straight pipe in, muffler is stock). I was on ebay looking at resonators to tone the noise down. Could I build one ie, 2" to 3 or 4" adapter run a 3or4" pipe for a foot or so and back down to a 2" before the flange? Would that work or am I better off putting a glass back in? If glass pack, what size diameter? Thanks guys and gals.

Brando · Brando's Garage

Aluminized glasspack... They're based on inlet diameter. They just kill the higher toned noise down. eBay has red-hots (what's on my teener) for $15-$50.

blk924s · 07-16-2007, 11:51 AM

I'm gonna scrap the idea of running a straight pipe too and put a resonator in. Thoes red-hots look interesting... Since theyre alluminized, how is it going to be to weld to the stock exhaust? I have heard that alluminized too...?

Spievy · 07-16-2007, 12:35 PM

I could be wrong but I think the "aluminized" means it is a coating, not actually aluminum. I was looking at the red-hots also.

bholmes · bholmes's Garage

Aluminized is just a coating. It welds just fine for me.

Marcone · 07-16-2007, 05:35 PM

Eww..dont use those.. i used them.. they are horrible sounding..

Spievy · 07-16-2007, 05:42 PM

I am talking about using them (redhots) as a resonator (because no cat). Not for a muffler.

Marcone · 07-16-2007, 08:35 PM

Ok may be good the..but ... do not use em as a muffler.. as some people do.. cheesy sounding.. looks cheap and just plain out crap...

as a resonator... i dont know.. but hopefully the muffler kills the rest of the noise...

Gordon Rankin · 07-17-2007, 12:07 AM

I suggest that someone check the various law statutes. In Calif, if you have removed your cat, the fine is in excess of $1000.00 and possibile suspension of your license. (At least thats what I heard). Also, any muffler shop out here (Calif) that removes a cat and replaces it with straight pipe, is looking at losing their state licensing and severe fines. Let me know if I am wrong but I dont think so..

flash968 · 07-17-2007, 05:19 AM

gordon - you are essentially correct - much of this will also become 50 state policy in less than 2 years, though i believe that cars over 20 years old will be exempt

this also does not address the obvious issue of what it does to the mixture (most cars tend to run rich down low when cats are removed, frequently increasing wear on the rings) - nor does is address what it does to the environment

yes, the car will rev a bit freer, and you can pick up as much as 3-4hp (albeit often at the loss of some torque), but unless you are dealing with a race car, the complications are significant enough to steer clear - there are a lot better ways to get more power without the problems

Spievy · 07-17-2007, 07:49 AM

I am hoping about the 20 year exempt policy. In VA they tend to do things like that. However, I KEPT the cat just in case

Marcone · 07-17-2007, 07:59 AM

The exepmtion policy as i read it here..(in canada) cut off at 87 so any car before 87 is ... but doesnt apply to everything that is 20.. which means... a car from 1995 will not be exempt in 2015...

Spievy · 07-17-2007, 08:10 AM

good point

Eldorado · 07-17-2007, 08:22 AM

but it's also law here that it is illegal to remove any measures that help emissions reduction that come on the car from the factory, so we cant just rip out the cats on cars that are 20+ years old.

Slam · 07-17-2007, 08:44 AM

Interesting topic. I tried a pre-muffler in place of the cat on my car and ity ended up being a cheap piece of junk - the internals came loose. So I got a used 944 final muffler and went off to my local shop. They welded in a big piece of straight pipe where the resonator had been and slapped the muffler on. The car ran better instantly - the difference was amazing. Free-revving, more power, far, far better sound.

But that's in Alberta...

flash968 · 07-17-2007, 09:46 AM

eldorado - same here, though enforcemnt becomes nil because there are no more inspections to catch those things once the car is 20 years old

slam - as i said, (assuming it's a normally aspirated engine) it is usually more free revving, and a little bit of extra power up top, but usually at the expense of some low end torque, which for a street car, is a big problem - i would get an A/F chart though - the low end rich running problem is pretty consistent with cat removal - a symptom of this is a sooty exhaust tip

blk924s · 07-17-2007, 12:22 PM

any idea why no cat causes richness? i think the only effect deleting the cat would have on the engine is the backpressure which would be lessened, causing exhaust to travel quicker (?) out of the combustion chamber, and possibly leaving a cleaner space for the next mixture to ignite. The O2 sensor before the cat would be reading the same amount and types of exhaust gasses, so I dont see how this could change the mixture...?