Emissions discussion inside.

So emissions equipment. Over the years it has gone from car killer to barely noticeable.

So when you do a swap and stuff are you trying to kill an endangered species every 20 miles or are you trying to grow hemp for clothing and stopped wearing deodorant?

What do you guys do in the tailpipe department or do you even bother?

Anything I build / screw with ends up with a functioning cat (or 2, depending on the setup) at a minimum. If nothing else, it saves me from having to deal with the thing stinking in traffic, etc.

On most swaps I remove things based on simplicity, or lack of challenge budget room for a cat, or complications with mixing and matching parts from different lines coming up with no matching egr tube. I would argue though that a new generation efi modern engine swap(properly tuned) is going to run cleaner without a converter than the old hunk of carbed iron with a pellet converter it's replacing

If i can i'll put a converter on. Wayyyy back when my tpi swapped camaro had a pair of them, unfortunately catco cats are barely better than a straight pipe.

In reply to FlightService:

I ripped it all out of the Vette, though that was largely due to the carb conversion...which was due to how flakey the 30+ year old TBI can potentially be.

It's not a car that will be driven much, and when it is it'll likely be driven aggressively for short distances, so I don't think the carbon footprint will really increase.

My 67 Camaro 6.0 swap has the canister and vent solenoid mounted and plumbed. I didn't add the cats, but i made exhaust with rear O2s and a place for the cats. The van ones were just too darn big, and I didn't feel like spending that money right now.

I usually minimize for simplicity. I used to either swap parts back on for the biannual SMOG or pay a little extra to overlook the visual inspection. I've always been able to pass the tailpipe sniffer test with or without all the hardware installed though. As far as I'm concerned that should be the only thing that matters.

Now I'm registered in a non-SMOG county, so I "accidentally" put a turbo on recently.

At the bare minimum, everything gets a larger high flow cat. That includes the RX-3 which isn't required to have one. The MS3 kept all the ancillary controls (EGR etc) and is tuned around a high flow. It also got a catch can which is technically illegal as it modifies the PCV system but, outside of one experience, no one cares.

Most everything not modified within an inch of its life retains the stock equipment including the carbon canister, the EGR, and the cat.

Only exclusion is something that is truly offroad only like a challenge car or a full blown track car.

I put a cat and O2 sensors on anything that'll have electronic engine control. The O2 sensor after the cat is a true mixture sensor, with less unused post-combustion oxygen.

Having just done a swap it's in full planet-killer mode right now but I figure I'll put on a high-flow cat when I get everything settled down in terms of tune etc.

Being on vacation, typing is a pain. So I will on Monday.

In reply to alfadriver:

Get ready for a rant guys!

The Samurai swap was complete with all the emissions crap. All the way back to the cat. I'm glad it is. I've gotten to where I hate smelling unburned or incompletely burnt fuel.

Of all my vehicles, the only two that don't have cats are the Abomination, aka Stinky, and SanFord. Both of which are carbed.

SanFord will at some point get a modern engine. When it does, if gas, it will have a cat.

The Abomination will always be a planet killer. It runs 10 minutes a month, so I'm not too worried about it.

The Rice Rod will have the original 2JZ cats because I still have them from the donor and that car will look terrifying enough without being enveloped in a cloud of stanky toxins.

Our rallyx car, which does not run often, has no cat as a result of some exhaust repairs (the 220k mile cat was pretty much gone anyway). Its something we intend to fix soon.

Everything else I've owned or modified I've always kept the emissions system intact.

Related note: just how far gone does a cat need to be with OBD2 to throw a code? My DD is getting awfully stinky and at 20yrs old/170k miles I feel like its reasonable to expect the cat to be dying. But no codes yet.

I would keep a cat and carbon canister. Cats because they're easy and catless cars stink, carbon canister because I don't like fuel fumes running around.

Depends on the car as well, of course. My MG is far cleaner now than it ever was new.

I find I get headaches around cars that have had the cat and/or carbon canister removed.

Keith Tanner wrote: I would keep a cat and carbon canister. Cats because they're easy and catless cars stink, carbon canister because I don't like fuel fumes running around. Depends on the car as well, of course. My MG is far cleaner now than it ever was new.

This....

In addition, it is nice to be able to retain MPGs... my car came with a 35mpg rating, and I've managed to get 32mpg from here in real world driving

Cat + Evap canister here, too. It's cheap and easy these days.

I replaced a cat on my Volvo where I could have gotten away with just a pipe - it's the secondary cat, after the rear O2.

I have a motorsports cat for my stock-engined RX-7, and the Quantum, if I ever get back to it, will have a 3" high flow cat.

No reason not to, this day and age. I've worked on and driven 1000hp cars with actual catalysts (not letter-of-the-rules "technically" cats) and full OBD-II compliance.

Evap stuff is a no brainer. It actually HELPS an enthusiast car, IMO. Some prior doofus removed the evap equipment from my '84 and when I park it in the summer, I can expect to lose about a gallon of gasoline per week just from evaporation. And the low-volatility fractions of the fuel left behind aren't exactly the easiest to ignite, so drivability suffers until I run the tank out and refuel.

ProDarwin wrote: Related note: just how far gone does a cat need to be with OBD2 to throw a code? My DD is getting awfully stinky and at 20yrs old/170k miles I feel like its reasonable to expect the cat to be dying. But no codes yet.

Depends on how tightly wound the PCM is.

I have dropped exhausts on certain Ford products to find that the cat shell had completely emptied itself. Went into mode 6 data and found that the computer was passing the catalyst tests with a wide margin.

This is why one should NEVER, EVER allow an emissions test center to run your car on the rollers if they can't do a scantool test. Locally, if you fail a roller test, you have to PASS a roller test. Running the roller because the DLC is dead now went from having to replace a 50 cent cigarette lighter fuse, to $1000-1500-???? to hang new cats on the thing.

I see this happen at least once a year and it's heartbreaking.

Keeping the engine as 'clean' as possible is good for our hobby. Nothing worse than being in front of soccer mom and having her notice, in a bad way, your car. They'll be happy to support legislation to eliminate us.

Given how cheap high flow cars have gotten it's hard to justify not putting them in. I don't think they even cost you many ponies these days.

If I convert my OBDI cars to run on E85 and keep the cats will the exhaust smell like popcorn?

When I swapped an inline 4 in my VW Vanagon, I left out the cat since there's not much room to work with back there. But my carbon footprint is offset because I don't eat meat.

vwfreek wrote: But my carbon footprint is offset because I don't eat meat.

In this respect, I think my non stock engined RX-7 either gets a pass since you have to BURN hydrocarbons in order to make CO2 and under most conditions the fuel will pass right on through unhindered by such crude processes as "combustion", or I need to become a 4th level vegan (don't eat anything that casts a shadow) to balance the scales.

I started it for the first time in a few months today after installing a new exhaust. Inside a garage. After about fifteen seconds, the air was bluish If you take an audio clip of a ported rotary, and slow it down enough to hear the individual exhaust pulses, you can easily hear that characteristic idle is the engine firing six times and then misfiring six times.

Still doesn't smell nearly as bad as any Diesel, at least. And that is before the fuel scents I like to use.