well, I just installed a bonez cat from rx7.com. Let me just say wow, my old cat must be really clogged, because there was a big performance difference. the car revs ALOT faster. I was a bit irratiated because the new cat does not come with studs, so I had to run over to the hardware store (without a car) to get some nuts and bolts. I also picked up some new gaskets, but overall, I'm very happy, let's see if I pass smog...

Alvin

 

The previous owner of my 85 GSL had a Bonez cat and RB muffler. Somewhere I still have the slips where he passed GA emissions with nooooo problems.. (also worth mentioning the carb was tuned very well also).

 

I passed with my turbo setup also.

 

I always pass with my Bonez cat.And they definately dont pose a restriction if you get the right size one.My 3" passes 14psi of turbo boost no problem and I still pass tough CA smog standards,even with a streetport 13BT.
It should be said however,that any cat no matter how good,cant process properly if the ACV and airpump arent hooked and working properly.

 

Well, I have all the emission stuff hooked up ( i think). But I'm hopeful! though the cat smells really bad with whatever paint it is burning off, that should go away in a couple of days right? it also pops a lil bit on down shifting, so my mixture might be wrong. I'm going to have mariah take a look at it next week to make sure everything is good. I'm just amazed that no one has talked about the power increase with the bonez.

Alvin

 

do you leave that cat on all the time or you take it off between smogs?

 

All the time.No need to pull it,it doesnt hurt perfromance.Most modern cats dont restrict if they're sized correctly.Nearly every car sold has a cat and there are plenty of 300-400-500 horsepower factory vehicles out there that pass CA emissions just fine running them.

Most of the time,your not feeling a HP increase from changing a cat.What your feeling is the HP RETURNING to factory levels because you replaced a restrictive or melted down cat.The original pellet cats used in the 70's-80's were horribly restrictive even when new.They made them extra large(and heavy) to compensate and keep the engine resonably unrestricted.But once they broke down internally,you might as well stick a banana in the tailpipe.

And, poping/backfiring is quite common on rotaries.Its because of the air injection and excessive amounts of unburned fuel that our engines pass into the exhaust system.Later EFI cas dont do it as much since they cut fuel on decel,but carb'd 12A's still send a lot of fuel into the exhaust.A hot,functioning cat will burn it up and send out a few pops here and there when you shift or decel.Just be sure all the hoses and vacuum tubes to the ACV and airpump are hooked up and the rats nest is all there.You should pass no problem.

 

Glad to hear it worked out for you. I'm putting mine on next week hoping that it will pass CA smog.

I look forward to the performance gain you're talking about too. I was a bit unsure, but I figured what the heck... more power, probably pass smog, much cheaper than stock replacement... where's the downside?

 

There is none.So long as you get a rotary specific cat like a Bonez,(or a large enough standard cat,that can tolerate our high HC levels) pitching the original pellet cat is the best thing you can do for a 1st gen that has to pass smog standards.

Just dont get a cheapo universal muffler shop cat.Those little things wont last on a hot running rotary.

 

does bonez make a 3" cat? I already bought a racing beat presilenser I was going to run all the time and swap in a cat come smog check time. I guess it's still cool because I can run without the air pump until I need it.

 

Thats what I run.Its for the FD,but Rotary Performance sells it without the FD specific piping.Just ask for a 3" Bonez blank.
Its cheaper than the full FD cat,but still about the same price as a generic muffler shop cat.Install can be 20-40 bucks depending on where you go.

 

Make sure you get some new exhaust gaskets and 4 sets of hardware to go with it. You are also going to need a way to cut a small metal pipe (i used a dremel). The cat doesnt' come with hardware, and it is also gonna stink for a couple of days as the paint burn off. So far, I'm very happy with it. Next thing is a rb muffler and see if I can find a header to fit in the stock location. I'm fairly confident i can pass somg at this point.

 

Wouldn't a header = instant death for emissions?

 

Yes, but I can swap it out for smog time. but, if i ever get pulled over, most cops will be able to tell if the cat is there, but they can't usually tell whether the manifold is correct.

Alvin

 

header itself dosent affect emissions.... unless you disconect the air hoses that run the emission equipment.

 

^well, that's what I was getting at. Most headers and related exhaust equipment are designed to bypass the smog equipment.

I would be afraid that the bonez might be too restrictive for a header pass, or worse yet the bonez be damaged by NOT running smog equipment. Someone else may offer more insight on this aspect.

That would suck if you go to reattach the stock manifold/air-pump only to have the cat fail.

 

? I'm kinda confused, the stock manifold doesn't have any emissions hook up? I know there is one heater hose that connects to the shield, but there shouldn't be anything else. What am I missing?

 

Yes,you can pass smog with a header.It doesnt affect emmisions at all since there are no hookups at its location.The 1-2 precats and their air hose on later models are moot when running a modern 3 way cat.A header,modern cat and functioning air injection/ACV will pass CA smog sniffer tests easily,Sport Compact did it years ago and put out only 4-5PPM of HC out of 120PPM allowable........

HOWEVER....There are no headers out there for our cars that are CARB certified to not affect emissions.Simply because its a long, costly proceedure to get certified.It may not affect smog,but if the header doesnt have that little tag,you WILL fail the visual inspection long before you get to the actual sniff test.

And dont run any cat without the air injection intact and working properly.You will destroy the cat without a steady,metered supply of air.Too much air all the time will overheat the cat and could burn your car down.Not enough or no air at all will cause the cat to clog up,restrict power and eventually go nuclear and melt down.

 

^ Thanks-for some reason I thought the ACV was removed with the exhaust manifold to run a header.
I live in a non-emmission state, so it all gets yanked without even noticing.