<VV> NOx emissions -- was Re: Air-cooled Diesels (CORVAIR) -

[Jim Burkhard]

One only needs to (maybe) worry about NOx on an emission test if ALL 
of these apply:
1) you live in an area that emission tests at all... where I live in 
(Western NY) does not... NO cars are tested here.
2) they bother testing old cars.  Lots of places let them slide if 
they are 25+ years old.
3) you are one of the small fraction of folks who unfortunately live 
in an area that runs emission tests on a chassis dyno.  Most places 
that emission test, still just use tailpipe concetration sniffers that 
are run with the car staionary at an idle or high idle.  Under such a 
setup, the engine isn't under load, so NOx is a minimum and they don't 
even bother looking for it. The concentration tests are HC and CO only 
and are quite easy to tune around if you really need to.

NOx only matters IF your car is tested on a chassis dyno.  If that is 
teh case, yes, enriching the A/F mixture will drop the NOx, but you 
will make HC worse in the process and CO will skyrocket.  So, the 
solution is not as simple as a second mixture map unfortunately.  The 
water injection would be a lot easier and more effective for that 
matter...

But is there anybody who lives where its actually required their 
Corvair be chassis dyno tested for emissions?

Jim Burkhard

FrankCB at aol.com wrote:
> Dale,
>     That reminds me that raising the combustion temp OR increasing the 
> A/F ratio in our Corvair engines both raise the NOx level in the exhaust 
> significantly.  The high temp can be solved with water injection while 
> the increased A/F ratio (even above stoichiometric 14.6:1) is not so 
> easy to solve.  Of course, we could have a SECOND and optional "map" 
> setup in our fuel injection program so that when we go for emission 
> inspection the car runs RICHER than stoich.  Reminds me of how I used to 
> manually "detune" the 140 just before I took it for the NJ emission test 
> and then "retune" it a half hour later in the company parking lot before 
> I drove it home.  But now it can all be done automatically by flicking a 
> switch.  Ain't progress wonderful?
>     Frank "libertarian" Burkhard