Manolis_D

iTrader: (2)

Hey!,
I was down at the local <V8> speed shop today getting 3" tubing and bends for my exhaust and it turns out that they have 3" 'high flow' cats. Is one of 'em going to survive on my car (it's a TII w/ a 3" exhaust and a Haltech, with which i'm trying to keep the stock emissions stuff)? I know rotaries burn hot, but the cats are supposed to get pretty hot to work well, right?

Also, the cats are quite a bit smaller than the stock one for my car, will I need two of them to make up for this? (I'm trying to pass CA emissions with the Haltech / J-spec deal...)

Thanks!,
Manolis

David88vert

I put one (3" high flow) on my ported GSL-SE about 2 years ago. I run extremely rich. So rich, in fact, that you cannot follow me without your eyes tearing. I regularly shoot 3'+ flames, that's feet, not inches. I have exploded mufflers even. My cathas somehow managed to not only hold up, but passed emissions last time better than my all stock 88 vert. I'd say it's a pretty good cat.

Manolis_D

iTrader: (2)

Who makes your cat -- it sounds pretty darn good

aZizzo

yeah, im interested in his too

aZizzo

Think i would be able to shoot flames out the Bonez superflo cat system wiht the apex n1 catbacks on a 90 GXL?

Manolis_D

iTrader: (2)

You could probably get some small flames. I know that people get like 3 foot long ones without a cat and w/ the Apex'i stuff...

I decided to go with a 'car sound' 3 inch cat (ordered from the local speed shop). They looked pretty decent, and the price (90 bucks!) seems very reasonable. I'll let everybody know how that pans out.

peejay

Who cares about flames? I wanna know what kind of converter that was

Manolis_D

iTrader: (2)

hehe, here here

kwikrx7

I bought a midpipe off the net and had Meineke weld on one of their hi-flo cats - works great. I don't use the airpump with it so it won't last for years and years but if it lasts me 3-4 years I'll be happy - $150 installed with labor - the number on the cat is actually the same number that Bonez uses for theirs - hmmmm....

13BAce

Just about all of the high flow converters that some of those rotary shops sell are just cheap converters. They just double or triple the price.

PaulC

If you are blowing flames your cat is not working properly !!!

The catalitic converter is coated with materials (expensive ones like platnium) designed to finish burning off the remaining unburned fuel so it is not released into the atmosphere. When cats fail they allow fuel to get by and released into the air (thus pissing off all the bunny-lovin, tree-huggin eco-nuts). WHEN larger amounts of fuel are heated by the engine and UNBURNED (passing by a cat that isnt doing its job) hits the atmosphere the sudden influx of fresh O2 to the HOT unburned fuel causes it to ignite and shoot the desired flames out the back.

In my 87 NA I was never able to shoot flames with my bonez high flow cat and single N1 set up. Also acording to Rotary Performance (www.rx7.com) a standard cat will not stand up to the higher exhaust tempatures of a rotary engine and the core of the "generic" cat will melt under the higher than designed heat.

Hope this eliminates a few misconceptions.

David88vert..... you really need to get your cat checked out. I would bet the guys at the inspection liked you and your car and made sure you passed.

Kwickrx7 ...... you need the air pump or the cat will burn up in much less time than 3-4 years, bonez numbered or not

David88vert

Sorry, you are wrong about not being able to shoot flames. My car has shot flames from day one with this ported motor. I run larger injectors and lower compression. The combo makes for large flames.

The car has been emission tested twice over the laaast two years at two different places. there is no way that they passed me due to liking me. It's highly illeghal here and they enforce it.

For your information, the unburnt fuel actually ignites when it hits the hot exhaust before the cat and the engine exhaust pressure pushes the flames out to the atmosphere. And it definately shortens the life of the cat. I don't expect it to last 10+ years like the stock ones. I never claimed that it would. But it has lasted 2 years already and passes better than my bone stock 88 convertible. It also only cost $200 - a lot less than the "rotary friendly" cats. I have run the Random Tech's ( I know one of their techs and get them at cost.), and they did not hold up near as well. The Random Tech cat melted in about a year. We also killed a Bonez that Ari's crew installed in less than 6 months. And this was on a TII that no one else had ever touched, and RX7.com had tuned it.

I have had pretty extensive experience with different cats, and have found this one to be th ebest bang for the buck. I am sure that it will still die an early death, but since it was cheaper, I feel that it is the best choice for me.

machinehead

I don't know about the T2 but the 3rrd gen airpump shuts off at like 2200rpm, so I don't know why everybody always says that the cats will die early. How often does your car run under 2500rpms? My car lives above 4500. The only time my car ever is below that is when its idling. It is one of those things that has just become accepted as fact and common knowledge but really makes no sense.

PaulC

I got that information from Ari and Rocky when I had my 87 NA being checked out at rotary performance.

So someplace there has been a misunderstanding, amybe some on both our parts.

machinehead

Maybe the ealier models did not have this function with the air pump shutting off? Do they have a clutch like on a a/c compressor? I know the 3rd gens have a clutch and they shut off after like 2200rpm. I ran a cat without a air pump for 2 years. When I had a backpressure problem I gutted it figuring it was bad only to find that it was still in perfect shape.
I gutted it anyway while I had it off. Still had the same problem. Afterwards I found the problem was not the cat but the muffler... this is one thing I know for sure, do not use a flowmaster on a turbo rotary.
Everybody says running without the air pump will destroy the cat. I don't know, my experience says different... now, if I were selling cats I may say otherwise. I am not really saying that I know more than someone else, because I don't think that, this is just what I have seen and what makes sense to me.

PaulC

I know that Ari and Rocky at rotary performance told me not to run my 87NA with out an airpump. Turbos might be differnt.

And the only thing that flows about a flowmaster is the name. Spintechs (even if they are square) actually create a vortex to draw the air away form the engine. Pretty wild if you ask me.

kwikrx7

I've been running my "Meineke" cat for 1 year now at 13-15 psi with many mods with no problems (not using the airpump)

mjw

iTrader: (1)

Barry:

Did going to the Meineke cat create a noticeable power difference for you?

Matt

Bonjo

Will the generic CAT reduce the noise? I'm bulding a Long Tube header and will be using a 24" muffler. I am worried about noise. My only concern is the CAT and Muffler piping is about 1/2 as thick as the header pipe. I was planning a slip on fitting so I can replace as they burn up.

The car is a Lotus Seven Styled rocket that will only be used on the road to and from an Autocross or for a Sunday Drive.

Scott 89t2

I used a "car sound" one too. they are magnaflow. much quieter with a cat then none.

as for the airpump. he told you to leave it on your N/A to work the 5th/6th ports. nothing to do with the cat burning up.

think about it. the cats melt from heat. heat is caused by burning. the reason the air is injected from the airpump is so it can mix with the unburt fuel to burn. no air pump, no burn. no burn, no heat. the cat will last longer with NO airpump. which I why I took mine off.

senn7

i put a bonez high flow cat and apex n1 dual on my 93 a few weeks ago. I am still curious to see if i am shooting flames or not. Havent had anyone follow me to tell.

adam
93 base, silverstone
new engine, new twin turbos, new transmission, rp 3" ss downpipe, bonez 3" high flow cat, apex n1 dual, m2 toe links, m2 trailing arms, bridgestone S03 pole positions, cusco front and rear strut tower bars, cross drilled rotors, NGK plugs and wires