Mister Willie

I know its Illegal-

What kind of performance increase would one potentially get by "accidentally" forgetting to replace your Catty with a new one, and instead replacing it with straight pipe on a 3.0 engine?

Elton

nothing at all

toy283

Yup, not worth the potential legal problems. Factory Toyota cats would be classified as "high-flow" from most any other manufacturer. A few years back, we did some testing on a friends '84 22R pickup. First we tested with the cat intact, then with a 1½" hole bored through the media, then with it all knocked out, and finally with a tube in place of the cat. 0-60 times varied by only 0.1 sec or so and a lot of that could be contributed to other factors (shift efficiency and timing, stop-watch timing variances, etc.).

trythis

Not only is it illegal, It is plain selfish and puts the person doing it into a lower class of existence. There are lots of things in the world that need to breathe the air a non catalyzed vehicle is poisoning. I personally like to breathe non poisoned air. This website is part of some tread lightly campaign that, I hope, includes the air.

dcg9381

Literally your hydrocarbons can increase by a factor of 10.
The truck will stink...
Not worth it.

FredTJ

I wonder why most everyone seems to think that "opening up the exhaust" or "putting on a 'high flow' exhaust", or changing to larger diameter exhaust tubing will somehow, magically, produce more hp and/or torque.

I suggest that you read up on gas velocity, surface reversion, etc., and then you'll most likely rethink your position.




Fred

ovrrdrive

I suggest you actually "try" what you're talking down about before you speak out of your ass again and see the difference for yourself.

I did some performance mods to my engine the last time I worked on it and nothing made that big of a difference at all until I did the exhaust. I litterally think it was at least a 10% gain alone. It made a huge difference. I didn't need to dyno it, I could feel it. It changed the manners of the entire powerband.


To the OP, I ditched my cat, and so have a bunch more on this forum that are keeping quiet because of the tree huggers around here. The fact is that if you keep your motor properly tuned up you are polluting less that others with cats are. Not only that, but I have read in several places that cats loose their effectiveness after 8-10 years anyway, so half of the vehicles out there aren't any better than not having one at all and in some cases maybe worse. If the cat is plugged, emmissions and fuel mileage will suffer which actually pollutes worse than not having one.

Did removing it give me more horsepower?

Nope. I just knew it was old and worried about it being plugged up, which it wasn't. The exhaust does stink a little more now but its not too bad. My engine runs pretty lean and is in great tune.

I did save the cat though when I had it taken off. If I ever need to put one in again I can do it pretty easily since I have it.

I have no regrets from removing it. The truck runs and sounds great.

dcg9381

That's absolutely untrue. No matter how well you tune your truck, there are unburned hydrocarbons. There are enough hydrocarbons that our lousy noses can smell 'em. One of the main functions of the catalytic system is to burn these off rather than release them to atmosphere.
When I said it's literally a factor of 10, I know because I tested it with a 5.0L Mustang. I ran 10x over what I should have without catalytic converters.

Hey, if you call me a tree hugger, that's cool.. I just don't think that our our vehicles should pollute as much as 10 catalytic enabled vehicles because we like the sound or want to pick up 1-2 hp. You get to make your own judgement.

The more pollution we have, the more the government cracks down. Hell in 20 years, it may be like California all over the US and that'd be a real pain in the ass.

I've got a 88 runner with a stock OEM cat. It still works great and my emissions are well within limits.

You figure of "half" is based on nothing other than self-justification.

With a plugged cat, mileage and pollution may suffer, that's absolutely true.
In my experience, when a cat gets plugged, it's pretty easy to tell.



Then why mess with something that's working right?

slosurfer

You would have to take it to some "shady" shop to be able to pass smog.

bodo

Yeah overdrive damn it we should ban all those cool classic cars to they are killing us. And Cali with the toughest emission regulations in the country has actually reduced smog. Hey here's a thought why don't you tell all these politicians to drive there lazy asses to a function instead of flying if you want save the air. The only CAT that will ever be on my Toyota will be splattered on the wheel well.

4Runner 4Play

Just do the right thing and leave it on. Quit beating the --->
Cheers, Lee

jsnby

I live in Cali and dealing with smog laws sucks, but my experiences have shown that Toyota's tend to run better with some back pressure, such as having a CAT and smaller exhaust. That's why i'll never not run a CAT on my Toy. And, as an added bonus, my truck won't get impounded by the damn city cop that decides to pull me over.

Cebby

Time for a rule to make even discussing this a bannable offense. Beating a dead horse is a gross understatement. Removing it is wrong. I will gladly BAN those promoting it.

Actually, I'm sure this in some way is against the ideals of tread lightly - (the TL ideals are not limited to guarding against turfing no-trail areas ya know). So in a round and about way, you are breaking a YT forum rule promoting it.

bodo

Maybe I get my backpressure from the LC header, test pipe, and stock muffler. Just for the record my cat was done from extreme blowbuy clogging it with oil so I gutted it a year ago. When the motor finally blew and I replaced it with the stroker I just put a test pipe in it. Now I think my EGR is bad if I find out that is bad it'll be gone also. Where does that black tar crap in your plenum come from? Exhaust gas maybe? Hey I'm all for if it ain't broke don't fix it but if it's broke and I don't need it I'm not shelling out any cash. I don't live in the stata of California so nobody is taking my rig unless I'm drunk or dealing drugs.

bodo

I wasn't finished typing when you posted that but if you want to ban freedom of speech than ban me first, I'm stating facts that could help people with offroad only vehicles that are cat exempt. How many rock buggies have Cats? Whatever you want to do. I came to this forum from wildyoats because overdrive (whom I never met) said you were more openminded.

AH64ID

I have run cat and no cat. Huge difference.. No cat sucks. The exhuast stinks horribly, so bad that I couldnt keep the rear windown of my 4runner open anymore.

Cats are CHEAP, a hi flow cat from carsound (magnaflow) is cheaper than a decent muffler.

As far as performance it seems to be better with a cat. Its only noticible on the bottom end, but my 92 w/ a cat seemed to have a better bottom end than my 95 w/out.

Dont forget that the fine is something like 25K.

Not running a cat is silly, and as other have said selfish... and I am by no means a tree hugger...

bodo

I guess nobody is going to say anything about that black tar crap in the plenum that we all love.

AH64ID

Bad PCV valve...

and as far as removing the EGR... why your engine wont run properly without it. Its not a power robbing system.

bodo

Nope that's new. Your engine will run properly without it, nope just have to tune it to do so. Toyota built an I4 then they made it pass smog. I'm hardheaded and if this keeps going I'll get banned so I'm done with this thread/post. I will answer direct ? through PM but I will not hijack this one anymore.

1989toy4wd

I was having some running problems with my truck and decided to change it, and once I took it off I realized that it wasnt the problem...because it was gutted!! I put a new one on, and the only difference I noticed was a quieter exhaust note..no difference in power at all!!

Also, you do not gain power by putting an exhaust on...you free lost power...its already there, it just needs to be released!!