I was wondering what the guys with headers have been doing in regards to emmisions. I currently am installing a header, unsure of the brand, which is eliminating my 2 precats; if I run only my main cat will I still be able to pass emissions?

Also, anyone know where to get some header wrap in or around the GTA?

Alex

 

most likely you will NOT pass. even if your stock main cat is still working, it is only really effective at "filtering" the necessary emissions out if you have the first 2 cats (it is a process, not simply putting a bunch of things in a row that do the same thing).

*disclaimer i don't condone/am not responsible if you take these actions*
your best chance would be to get a decent aftermarket cat with an air inlet, and hook it directly to your airpump. do not run the car like this for too long because the cat will burn up quite quickly. you could also add a percentage of alchohol to your fuel. if you have something to adjust fuel, like the SAFC, lean it out but not too lean.

or, you could do like me and have your car registered in a county that doesn't do emissions testing.

 

Are you sure? Everything I've read to date says that the FC pre-cats exist to warm up the main cat as quickly as possible and make no substantial contribution to emissions control...

Not looking for an argument - just want to give the guy (and myself while I'm at it ) the right info.


And instead of alcohol, I would suggest methyl hydrate.

https://www.rx7club.com/showpost.php...5&postcount=31

 

yup, you are partially correct. as i understand it, 3-way catalytic systems all work the same way. you have the 2 pre-cats that actually burn up HC and CO, and this in turn increases efficiency of the main cat reaction (an endothermic reaction).
if you don't have the first 2 cats the main cat won't be as effective. that's just the way i understand it though, so i might not be entirely right.

 

Well I test drove an S4 one time with a header and Bonez cat, it had passed emissions like that. Keep all the rest of the emissions in tact and you'll have a decent chance if the engine is running right.

 

Thanks for the responses so far guys, keep it up!

Well, all 3 cats have less than 8000km on them so I hope my engine hasn't burned them up quite yet. The engine is running pretty good too, I'll probably just end up running emissions with all 3 cats if it's going to be a hassle, it only take an afternoon to switch out headers anyways. I just hope that I can pass emissions this time, managed to fail last time due to injector cleaner, a mistake on my part.

 

FWIW I have passed a couple estests on only a main cat (and air pump, acv, etc.) but no header, just the regular ol' maniold.

But either way, only 1 aftermarket white box (el cheapo) convertor

 

An 87 I built and sold passed with a header on it. It had the air pump and a 2.5" aftermarket cat with about 20k on it. Took quite a bit of messing around though. Obviously no guarantee that it will work. It is possible though, as long as the 5th&6th ports are working and all emissions equipment. It would most likely be easier just to run the stock setup for the emissions test though.