Stinky FD exhaust with resonator pipe!!
 

I've recently rebuilt the 13B in my 1992 RHD FD. Its a stock motor aside from:

• Street ported housings and super seals
• Replaced the original cat for a resonated straight pipe (removed and blocked off emissions stuff)
• Stainless exhaust

Without the cat when I run it in my garage the exhaust looks good (no smoke etc) but is very stinky, the sort of stink that sticks to your clothing. It does seem to be running a little rich so I hope the Power FC I ordered can cut that down a little and smooth it all out.

Anyone have tips on reducing that stink, I thought about replacing the straight pipe for a high-flow cat but I really don't want to hook up all the emissions stuff (air hose) again since I've already blocked it all off.

Any input is greatly appreciated!

I hate to say it, but I have yet to see a non-smelly rotary. My eyes tear up when I'm near the car, my friends never want to drive behind me, and I hate taking my car to work since I wear shirt and tie and I don't want to pay for dry cleaning all of the time.

https://cimg9.ibsrv.net/gimg/www.rx7...1a12757824.jpg

I'm actually curious if there's anything other than putting back the factory emissions..

I think you can just put a cat in without hooking up the emissions stuff.

My friend has passed etest with everything blocked off, no airpump and just by tuning it with the PowerFC.

I do believe a high flow cat will reduce most if not all of the stink. However, WO the airpump, I suspect it will burn out the cat faster, but not 100% sure on that claim.

^ when you guys say stink,, do you just mean the smell of unburnt fuel and a touch of 2-stroke? If so, that's part of the charm! What kind of annoys me is the bit of smoke on start up and over-run while driving.. would a high-flow cat fix that at all? No pollution gear or air pumps on mine.

You might call it "charm." My wife would politely disagree with that assertion. She can tell everytime I arrive home if I've been with "the mistress" (my FD), based on how my clothing smells. It requires a shower before bedtime :)

I'm guessing you would still get some startup smoke WANKfactor, but what exactly do you mean by "over-run"?

By over run i basically mean lifting off the throttle.

Your charcoal canister line in the rear may have come off. If filters out gaseous fumes from the tank.

A high-flow cat will all but eliminate the stink and you'll probably be surprised on how little it reduces power. You might also like the sound better. I've been running a BONEZ cat without emissions for over 10 years and it's still going strong. It won't miss the air pump and you don't have to worry about boost creep on the twins either.

Embrace the petrol fumes, let them become one with your pores.

I've run a quality high-flow cat for years, it cuts the stink WAY down and you do not need to run the air pump/emissions with it. A good high-flow cat will be VERY little restriction.

If your car is running richer than normal it will make more stink. If you have a stock ECU and no air pump, it will run much richer and of course be stinkier. The air pump messes up the O2 sensor readings, the factory ECU compensates for this, but if you remove the air pump the ECU doesn't know and it compensates the wrong way. Makes the car idle crappy and it's jerky on/off throttle. Easily fixed with a PowerFC.

If you get REALLY poor fuel economy that's a sure sign of being too rich. Bad plugs, bad o2 sensor are common culprits.

Dale

^^ listen to him. Solid advice as always Mr. Clark

Yep, switching in a high flow cat really improved smells/emissions with really no downside for me, definitely a worthwhile switch to make.

Thanks for the feedback all, I did a little more research after reading your suggestions. I think I'm gonna go with a Metallic Substrate HighFlow Catalytic Converter and have it welded into my downpipe, apparently they work great and don't ever clog etc.
Magnaflow 59956 | 200cpsi | 2.5"in/out | Metallic Substrate HighFlow Universal Catalytic Converter
I mocked up a quick image of what I'm thinking:
https://cimg4.ibsrv.net/gimg/www.rx7...559c3b2a0b.png

Good, bad, ugly?

No need to mess with the downpipe/precat. Just replace the main cat or your midpipe with a Bonez or equivalent. :icon_tup:

EDIT: Yeah. What sarge said.

Good points Sgtblue/Natey! I've heard tho the stock mount high flow cats can clog or overheat without the air pump hooked up, I wonder if anybody sells a bolt on cat that's intended not to have an air pipe installed, do you guys know of anyone selling a cat like that?

Just get a RP/Bonez cat and run the air pump. I don't understand why don't you want to run the pump? You have stock twins based on the downpipe, so turbo clearance isn't an issue.

When I tune/log I disconnect the air pump plug and the exhaust gets waaayyy stinkier. Also, when I run my air pump I get better exhaust pops on decel and off throttle. I guess that's from the added oxygen allowing unburned fuel to combust. Win/win IMO...

High flow Bonez main cat and air pump FTW.

Sgtblue you've convinced me, stock mount high flow cat it is. I'll just block off the air pipe inlet.
alexdemin, I'm planning to install a single turbo in the near future so I'm slowly checking off things like blocking off the emissions etc..

It's pretty easy/cheap to buy and rig up an RX8 electric airpump, and wire it to the original plug to trigger it (you may want to actually draw power from a more direct source), and you have a lot of flexibility with where you place it.

Or remove it if you don't have emissions testing, are moving to a standalone ECU and want to simplify. The only thing you should consider since you're also going single is a Pineapple idler pulley.

I've read on here that people have had luck running the SMB metallic substrate cats with no air pump without it clogging, etc. I was thinking of running one to just cut down on the smell (I have no air pump so didn't know how long the HFC that came with my car would last). SMB's are crazy expensive but there are some other places that sell similar ones, I believe.

My SMB Metal cat melted, probably caused by bad HKS TP misfiring though

https://www.rx7club.com/3rd-generati...p-pics-668417/

^ doesn't matter. SMB is defunct now. Which is a damn shame. Best rotary mufflers on the market (if you were local)