I just had a new re-built engine installed in my 1988 Rx7. I need a new cat, and I was told by the guy I bought the engine from that a after market cat will KILL my engine and they don't make OE cats anymore. Can anybody tell me if this is true? If not, any recommendations on the best after market cat for my car. I was told by a local mechanic, Magna Flow. You help on this is highly appreciated. Thanks, Bob
Ps. I'm in NJ.

 

I'd love to hear the explanation about why an aftermarket cat would somehow kill your engine.

Here are some cat replacement options: http://www.rx7.com/store/rx7/fcexhaust.html. There are lots of others as well. You can buy some direct replacements from generic auto parts stores too.

The OEM cats are still available (most), but a main cat for an S4 is about $1500! http://www.mazdatrix.com/e5.htm

 

Thanks for your help. I've printed this and will talk to my mechanic
Bob

 

If your mechanic is the one who suggested that an aftermarket cat will kill the engine, run, don't walk, away from the shop...

 

The advice you got was nonsense.
The vast majority of us with 3rd Gens. have aftermarket cats. Mine (a BONEZ hi-flow) is over 8 years old and it's still probably more efficient and presents less risk to the engine than a stock cat. And many reports of owners passing emissions with them.
Just get one with a proven record.

 

Just installed a magnaflow cat on my 90' GTU last week, I found it online for under $100. The original cat was mushy to the touch.

This part bolted right up to my S5: Magnaflow Part #M6623688

Not sure if it will work on the S4 N/A, but perhaps someone else will chime in...

 

I am going to go Bonez or Magna Flow. Seems to be the recommendation of a lot of people in the know. Thanks a lot for your input. Good luck with your cat.
Bob

 

I had a universal wleded in at a local shop for 165 bucks, not only did it clean up my emissions substancuially but the car runs beautifully.

The guy you're talking to probably doesn't know much about angry spinning triangles. Just sayin'.

 

hey guys if anyone else changes their cat to aftermarket pm me, i pay good money ($100+) for old stock units even if they are bad.

 

What use do you have of old bad cats? You'll not recover $100 worth of materials from them, and it is illegal to install a used cat on a car.

 

Used converters are ok as long as they have been properly tested and relabeled appropriately EXECPT in CA. No used catalytic converter re-certified or not can be sold or installed in CA.

 

yes i will recover more than that. i wouldn't come on here stating i did if i didn't. already paid 6 or 7 members on here for their cats.

 

so a 7 owner in california cannot buy a used cat, they cannot buy an aftermarket cat and the cats have been discontinued new then what option do they have?

the more i think about how fucked up california is the less i ever want to even visit, lol.

yeah, i can easily see someone paying $2k for one of the few remaining new units for a car that has a blue book value of right around that same figure. just like they think they know that you can't modify an engine and make it burn reliably clean to pass emissions... politicians these days make me angry.

 

What kind of mechanic says that? That's all we do is add aftermarket stylings to our cars....RIGHT? LOL. That just shows he got his degree from a 3rd rate school. (no offense)

 

technically he is correct.

most aftermarket cats use inadequate materials which eventually fail quite early, fracture and block exhaust airflow as the monolith pieces turn sideways and act as a wall. this does restrict exhaust and causes the engine to retain more heat and cause EGTs to rise excessively which can lead to detonation and premature engine failure.

this is however less likely to be an issue with a main cat as opposed to a pre-cat which sits right off the engine and leaves only a small amount of space for the exhaust gases to escape causing EGTs/combustion temps to rise much more than if there was no precat and the main cat simply failed.

Magnaflow and Bonez converters are about the only aftermarket units i have seen be able to hold up to the extreme EGTs of these engines for more than 2 years in a well tuned environment. even the high quality stock precats only last about 5 years before they begin to fail even in perfectly tuned cars as the expansion/contraction from heat fractures their core. good quality cats have a steel mesh that surrounds the core to act as a cushion for expansion contraction, cheaper cats either do not use this material or it is too thin for the severe heat that causes these exhaust systems to expand/contract more than typical + piston engine exhausts.

our typical shade tree mechanic test to see if the cat has fractured or not in the field was to tap on the cat with a dead blow hammer and listen for any rattling from inside the cat(dead giveaway).

broken catalysts will also result in intermittent loss of power, because the monolith blockage will shift periodically allowing more exhaust to escape than at other times when it shifts again to create an almost total blockage, as the material is loose in the exhaust and floats around at will. over time though it will tend to become more of a total blockage as tiny bits of monolith get plugged up into the usually still intact rear half of the catalytic "brick" or monolith.

is that good enough for everyone to stop crapping on the one mechanic's opinion? we already know that it is a wise idea to omit the precats on these cars, but did you understand why? because they can kill a motor. perhaps either the mechanic just didn't convey it properly or the OP didn't but his point is still valid.

now that you've learned something, don't you feel better?

for my opinion though, the precat is worthless on these cars. it only helps clean up emissions for a few moments prior to the main cat coming online. the main cat can obviously do the job on its own and failed precats cause more harm than good with excessive emissions for much longer than the short warmup period it endures for at each startup. generally a failed main cat won't killl an engine but i could foresee it as possible if the car is pushed hard enough with a failed main cat. precats should no longer be a requirement as overall it creates more emissions with engine rebuilds fouling the air and excessive emissions caused by control systems out of whack due to backpressure.

 

Just to add there are aftermarket CA certified NEW cats that you can purchase.... just can't be used or even re-certified like other states allow.

Which is why muffler shops that will slap on a used or non-CA certified after market cat will not keep any record the work done or the transaction... just to cover their butts.

 

well pretty soon they will have gas analyzers in heavy populated areas giving ref tickets to people anyways, so forcing people to use certified CA legal cats is a moot point.

 

Which is funny because even if every non-commercial car on the road was passing smog it still wouldn't even lower the total world pollutants by even 5% if I had to guess.

BUT just like George Carlin always said... "The planet is fine, it's the people that are F@#$."