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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.
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.
I'm actually curious if there's anything other than putting back the factory emissions..
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"?
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.
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.
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:
Not directly familiar with it, but given the heat energy of rotary exhaust I’d use one that is proven to last with a rotary. Maybe that one is.
A lot of trouble to pull the DP, splice and weld that in when you could just get a bolt-on replacement for your mid-pipe that’s proven to do what you want it to do.
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?
Last edited by peterpiper; 05-17-18 at 12:04 PM.
Reason: clarity
Do what you want, but you’ve also read here from multiple people that a good one doesn’t clog and tolerates having no air pump just fine. The Bonez has an air inlet that’s probably needed if you have emissions testing. Otherwise it can be simply deleted or plugged.
Good points Sgtblue! I've heard even 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. I read somewhere that "SMB" or something sells a resonated/cat combo unit, but I couldn't find anything.
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...
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.
05-16-18, 01:51 PM
Stinky FD exhaust with resonator pipe!!
