Nube question about catless header and emission
 

So it is my understanding that there are two catalytic converters in stock configuration, first one in the header and the other in the front pipe. But there are multiple manufacturers like HKS or Powercraft that sells catless header + catted frontpipe set, which are still able to pass emissions in Japan despite having only one cat.

How is this possible if the car still only has one catalytic converter in the entire exhaust system? Is the stock second cat that ineffective?

Not sure but I think the emissions requirements between the US and Japan are completely different.

My main question is, what's the difference in performance/emission between having two stock cats, having only one aftermarket cat, or having two aftermarket cats (by getting a catted header and a catted front pipe).

hmmmm @cheezy79, you may wish to check in with the folks on your local part of the forum.

http://www.ft86club.com/forums/forum...aysprune=&f=16

When I've taken newer cars into the WA emissions testing station, all I see them do is plug into the OBDII port. I don't know whether or not they can tell if the cats had been messed with or not by just doing that.

The older cars, they stick a sniffer up the tail pipe.

Maybe other locals can give better feedback ...... :)


humfrz

I have JDL catted header and front pipe. These are 200 cell cats. My car failed emissions testing here in Australia. I am in the process of getting some headers and front pipe from JDL with 400 cell cats. I will post when I get them fitted.

You just killed me... :sigh: I have JDL's catted header and was going for the front pipe soon, thinking the 200cel would be enough.

Do you know the specifics of the test numbers required for Australia? I need to pass european standards...

It really depends on how your locality tests emissions. A lot of the time, passing emissions is more about the tune than the hardware. In places that only check OBD codes/readiness, you can get away with only one or no cats if you run a tune that suppresses the fault code that the ECM reports when it's missing a cat.

If the emissions test includes a sniffer, most likely replacing or removing any cats won't pass.

The IM240 emissions test is a 240 second simulation that runs the car through a set/defined range of engine load scenarios on a dyno. This involves driving at different speeds, loads and gears. An exhaust gas analyser is used to tracked emissions in grams per km.

The gasses tracked are HC, CO, NOx, combined mass THC+NOx and particulates.

The emission limits are here:
https://infrastructure.gov.au/roads/...o_2_Euro_6.pdf

If you are missing a cat the system will generate a CEL. and in NH you won't pass emissions (ODB). You need to tune the CEL out with software is my understanding!


:cheers:

For just about everywhere in the US that does emissions testing (ignore California I'm not sure of their process) the system only cares about what the ecu thinks of the cat. If you tune out the Cat requirements you should still pass OBD emissions regardless of the actual effectiveness of the cat.

Hello, Any update on this?

I have a catted header and OEM frontpipe and concerned about emissions test.

I also have this crazy idea of getting an Ace header which is catless, then buying an extra OEM frontpipe and have someone weld the two cats together in one frontpipe. The idea is to run it on the street then when trackday comes, switch to a HFC frontpipe.

akyp: i had similar idea at some point too :)
Just that you still may see CELs unless those are disabled in tune, even if you relocate O2 sensors, as gas flow and temperatures might be different to what ECU expects, still having both stock cats just header's one relocated downstream won't let you pass emission tests for where relocating is outlawed too (like CA), +in most cases single stock cat in OEM frontpipe is enough. Cat in header mostly is to heat up sooner due higher exhaust gases temps closer to cylinders and thus for better emissions in cold starts. From what i've heard, in most cases/in many countries people passed with single stock cat in OE frontpipe. There were fails with replacing that second cat too to highflow/less cell cats though.

Passing emissions at street level for the local MOT, and passing emissions at manufacturer's level to sell a vehicle are two very different things.

There is no way to pass proper emission test with something else than stock cats.

You need the first cat as close as possible to engine out for emissions at cold start. Without it, you'll fail homologation cycle within the very few seconds. Californian law is extremely hard on that point.

I have been working on European emissions for the last 9 years. They are easyer than US, but you still can't pass without a cat very close to engine out.

You need proper cats too. Not the total BS metalic aftermarket stuff.
Aftermarket cats will only work to limit emissions for the driver on track behind you. They will easily turn off when driving slow in the city. (Especially when far from engine out)

Metalic cats are stronger than oem cats. This way they may survive increased horsepower on tuned cars.

I have ordered and paid for the parts. I am still
waiting for them to arrive. I am away from home atm and not in a position to check up on progress. I will post update in a few days time.