Maddog

Hi All

My 90 3.0 V6 Has no Catelatic Converter,It may not have ever had one or a previous owner has taken it off,Its very common for us kiwis to take them off the Jap imports we get,as they are seen as a restrictive item.

What do some of you think ? Is it a good thing or a bad thing to not have one(NB: emission's testing is not a problem here)?

also i have a very old standard looking rear muffler,How long to these last for before the need to be replaced(mines 140,000kms)?

also ive seen the term "catback" mentioned alot in the forum,what exactly is this refering too?

Mossback74

From what I've gathered here, the 3.0 likes the additional back pressure that the CAT provides. The bigger issue of course is being a responsible person and putting one on, even if it's not required.

Not sure on mileage but I'm sure it could stand to be replaced with a nice Dynomax

Catback refers to all exhaust from the Catalytic convert back. Pipe/muffler/pipe. I understand this may be hard to determine in your situation.

Just remember, to little backpressure = loss of tourque

Maddog

Hmmmm interesting.....Thanks Man

bike4miles

Gas mileage will decrease without a cat. The best option for toyotas is to install a high flow aftermarket cat. This will give you the best balance between the backpresure the cat provides and the extra hp from reduced restriction, or at least, that's what I have gathered. I plan on getting one of these cats as well as a magnaflow this summer for my 22re but I will ask my exsost guy and this forum for advice before I do.

Cebby

Put one on, the planet and the rest of us will thank you.

wvuviv30

worst gas mileage with out a cat?

Well I am not to sure of this, but maybe my old one (stock 125K miles) might of been clogged. I was getting 15 mile per gallon on the highway after a tune-up (new plugs & wires, new filters (air and fuel). I installed a test pipe and I am getting an average of 22 mph on the highway. I have the 3.0 V6.

toward the end of the summer I am re-doing my exhaust... no cat on a rusted out stock muffler sounds like poop.

Well what size universal Cat should you run and also what size exhaust pipe should I run? I was thinking 2.5" cat but with 2.25" pipe, or should I run 2.25" on everything? I was planning on having the exhaust dump under the 4Runner before the rear axle.

scharged03

I don't have the experience with the 4Runner but my mustang has been without a converter since I got it. You can feel the increase in power. As for engine warning lights, you can put in a MIL eliminator to take care of that. The exhaust is louder without it.

Pitchar

bike4miles

Yea, I'm not totally certain about the milage thing. I just heard from some guy on cardomain that his milage decreased a lot when he took his out so he put a new one on and it got better agian. Anyone else have more concreat info on this?

Sunday BBQ

Yup, from what I know, removing the cat is supossed to increase gas mileage. I come from the ricer world and lots of people would take of their cats. I wish all the frickin' Civics with no cats and loud-ass exhaust would put them back on though.

Maddog

Thanks guys,
now im really confused,taking the cat off should increase flow witch i have always thought was a good thing but so many of you say that you get better mileage with one on,
the main priority for my truck at the moment is to get better mileage,so i will ask the exhaust shop.but i reckon they will tell me the oppisite,one guy today told me that i should go 2 1/2 inch pipe not 2 1/4.but what does he really know?
I need some hard facts

Cebby

Removing the cat takes out TOO MUCH backpressure. You need some level of backpressure for the 3.0 to do its job.

terky

Thread jack real quick:
I found a system for my 22r. its made by Downey. It comes with a highflow cat and muffler. The size of the pipe is 2.5 inches. is that too big for a little 4banger?

Heres the link.

http://www.truckperformance.com/prod...5=Standard+Cab

Maddog

would a resonator do the same thing backpresure wise ?
What kind of mileage does your s get?

Bigkahuna808

I pulled my cat on the 3rd gen in hopes of gaining power. Big mistake. I not only lost gas milage, my power went down. My truck in strait drive used to run high 16s (low of 16.78), but with the cat out and cherry bomb in its place I ran 17 flats.
'
Just this morning I had a high flow cat added. I should have never pulled the cat for the cherry bomb (I replaced the bomb 2x for blowing out the glasspacking)

Id say never pulled the cat, to strait pipe or to replace with a bomb. Just add a high flow cat.

Maddog

Thanks ,thats very informative.

Maddog

spoke to an exhaust guy today to get a price etc....he was adament that if i dont have too, (& we dont in nz)dont have a cat,I tried to explain about the backpressure etc... but he said thats just a myth.he owns a v6 nissan terano 4x4(basicly are nissan 4runner for you yank's)he did his own system and swears he has more power & torque.he said he would basicly use the same system as his on mine.which would be 2 1/2 inch pipe with a resonator then tripleflow muffler.then maybe if needed another resonator.

he said if i was certain i wanted a cat id need a high flow cat that costs as much by itself as this whole system.

so whadda u do?

Bigkahuna808

having the rsonator will help with the back pressure giving you more power. The cars the beneft most from having no cat, are thoes full blow race cars, that you dont need everyday power.