Im looking at getting my main cat changed out to a catalitic converter that doesnt need air injection to function correctly.I believe I have a blocked or partially blocked main cat and I want to replace it. The reason I want a cat that doesnt need air injection is pretty obvious.I want to remove the air pump,acv and the vacuum lines and solenoids that go to the acv.Its a good way of symplifying everything a biut and will help diagnosing turbo problems now or later.

I called a local muffler shop and they quoted me about 275 for a universal cat and the piping needed to fit my car.I know some cats cost around 300 bucks.So I figure why not get a nice hf cat,stay emissions legal and also have a better built cat at the same time.Suggestions are always welcome guys. Thanx

 

You still need the air-pump to pass emissions, period. Supposedly the new Metallit cats don't need an airpump to pass but I have yet to see smog test results from anyone with one.

 

Remember, most cats aren't built to handle the exhaust temps of an FD.

And I would expect the cat to clog without the airpump, since FDs run rich much of the time.

Dave

 

midpipe

 

The guys at N-tech claim that you do not need air injection for their cat. I've run mine for 6 months without one so far (and it had 15k and approx 2 years on it before I removed the airpump) and have had no symptoms of a clogged cat so far.

 

I wish I could run a midpipe right now.Unfortunatly I cannot.
It requires porting the wastegate and also more than likely having a aftermarket ecu.So the metalit one may pass emissions. I actually have a midpipe lying around right now.But the other two factors are keeping me from achieveing my goal.
On another shitty note my fd is an auto.So changing out ecu s also means I lose the only redeeming feature on the auto.The hold feature.As you can see im in a bit of a bind at the moment.
I also see that a clogged cat kills the engine.So im also worried about my engine as well.I ws hoping that I could just replace the cat for the time being and saving up for some ported twins an a apex power fc to tune everything.It would still suck though because I hate auto mode.It upshifts too damn much and exactly when you dont want it to.Thats why I like hold mode.I wish I had bought a manuall to begin with.

 

I'll revive my old thread once I do another emissions test with the metallit cat. However, it still has the airpump attached.

 

You do to pass emissions....at least in California, other states may have more lenient requirements.

 

I'm also removing my airpump because it's making that mooing noise and can't stand it! What kind off pullies do you need after the removal?

 

I have also been running a N-Tech cat with no air pump for some time (and running rich) with no problems. Injecting air in the cat makes it hotter which should reduce the life of the cat. Some cats are just better made than others. I never believed the rumor about cats dieing because the air injection being removed. Anyone have proof?

The metal cats look very promising. Most will handle (clean) a lot of CFM of air for their size and weight. The JCWhitney cat claims 535 CFM which is very good. Anyone know what the stock cats CFM rating is?

Here are some links to some metal cats that can be welded in...

http://www.davesport.com/cgi-bin/davesport/DCAT325.html
http://www.jcwhitney.com/autoparts/P...p-8841/c-10101

They both look very high quality and reasonably priced. Just have a shop weld the metal cat in your mid-pipe. Make sure they use stainless welding wire or rod. I believe 308 stainless wire or rod is recommended (best) for 304 stainless. Most exhaust places are setup to weld 409 stainless so wouldn't be as corrosion resistant. A welding shop may be able to do better.

 

* 3-way = air injected to center of ceramic brick
* air pump is not need for cat, it's need for smog
* you can use a 2-way/regular cat' with an air pump and block off the tube and still pass smog.
* rx7.com now has the new Bonez metalit 2-way cat'.

 

Some good tech reading on cats -

http://www.randomtechnology.com/technical.html

The jury is still out as to the airpump and the cat. It is known that you NEED the airpump with the stock cat to pass emissions. Personally, I'd LOVE to ditch the air pump, ACV, etc. but still run the cat just for boost control and stinkyness reasons. The jury's still out as to whether this will cause problems down the road, shorten the cat's life, etc.

I've been meaning to call up Random Technologies and see if I can find a tech that really knows cats to quiz on this issue.

Dale

 

all very good info guys.most appreciated.What kind of cat is the knightsports metalit cat? 2 way without the need for air injection?

 

The cheaper Knightsport metal cat has air injection. It shouldn't damage it to run without air injection. A large enough CFM cat (metal or ceramic) should make it possible to pass emissions testing without air injection but would probabely still fail visual.

 

My suggestion would be to get a cheep cat. These cars are hard on anything connected to the exhaust. The point of a cat is to gain registration. Lets face it the smog tests anywhere don't duplicate normal driving of an FD. How often do you cruse at a steady 15 mph and 25 mph at 2k or less?? Once you get into the throttle all emission bets are off. No cat or emission system will clean up a normal driven FD. The idea is to have a cat and keep the exhaust flow good enough as so not to damage things. You also must have the air pump installed thats a deal breaker with a smog test. Sure the new cats might still get you by chemical but theres more to a smog test as we all know.

 

I used the air pump from the RX-8. It is an electric one so I still have the greddy pulley set on the car.

 

lucky for me colorado is doing away with emissions soon.So no worries there.I just need a cat for the exhaust restriction.So I dont get boost creep and blow the engine.

 

do you have any pics of this set-up?

 

how much was that electric pump. I've heard of people also using the electric pump out of vette's for the same reason.

 

The problem with the electric pump for the 'vette is it's not designed to run constantly - just for very short durations. I've heard of a number of guys trying the electric air pump that had it fail within a short period of time.

The RX-8's electric air pump is a possibility, but I don't know if anyone knows how it operates - all the time, just at cold startup, etc. Hard to say what kind of duty it's designed for. I also have a feeling it's not cheap .

Dale

 

Well, just got done digging through the RX-8's shop manual. The '8 air pump is a no-go.

According to the shop manual, it recommends not running the air pump for more than one minute, then allowing 1 hour for the pump to cool before running it again. I have a feeling it's just used for cold starts to get the cat up to temp quickly, thereby eliminating the need for a precat.

Doesn't seem like it would be that hard to make an electric pump that could put out 1-2 psi of pressure continuously. But, there may be something I'm missing in the equation.

Dale

 

I suppose the electric air pump is outta the question.

For the time being Im going to go with a high flow cat.I believe the hf will have enough restriction in order to avoid boost creeep. I realize that with my current mods I have to be very carefull. One thing I have noticed as of late is that my cat is rattling a bit more now and I also smeel that rotten egg smell when ever the car backfires at times. Now to make a decision on which hf cat to go with. Decisions decisions.LOL

 

Couldn't you just wire up a 12volt raft pump or something of that sort and just turn it on right before testing?!

-Alex

EDIT: Maybe a pump from this company, they are extremely small and could be mounted under the car or something and attached before testing with a switch in the cab and then taken off afterwards. http://www.clarksol.com/html/air_gasPumps.htm

 

Has no one tried this?! There has to be somebody...

-Alex

 

My county is starting emmissions in April, I've got a cat laying around but no airpump. Hopefully they will not notice...