Taken directly from my 260z service manual:
Anti-Backfire valve - [During the] initial period of deceleration...
the mixture in the intake manifold is too rich to ignite and burn in
the combustion chamber and burns easily in the exhaust system with the
injected air in the exhaust manifold. The Anti-backfire valve provides
a supply of air to the intake manifold, thereby making the air-fuel
mixture leaner, preventing backfire. The correct function of this
valve reduces hydrocarbon emission during deceleration.
(my comment) This implies that the air injected into the exhaust
manifold helps burn combustibles. Other things (such as the AB valve)
help to avoid combustibles in the exhaust in the first place.
EGR - the EGR system has exhuast gases recirculate into the combustion
chamber and reduces combustion tempurature so as to reduce NOx produced
in the combustion process.
(my comment again) Oddly, the section for the smog pump (called AIR
INJECTION SYSTEM) doesn't describe what if any emissions it helps, or
exactly what it does, other than add fresh air to the exhaust. The AB
valve avoids a problem CAUSED by the presence of the smog pump - namely
backfiring ("popping") due to air injected in a too-rich mixture in the
exhaust manifold.
--- Edgar Gonzalez <datsunspl311@home.com> wrote:
> Hi list,
>
> I thought the cold air injection into the exhaust manifold was meant
> to
> lower the exhaust gases temperature to minimize the production of one
> of the
> pollutants. I don't recall which one but I don't think it was the
> carbon
> monoxide. I thought the other pollutant needed a higher temperature
> environment to "manifest" itself. I could be totally wrong...
>
> Edgar
> San Diego, CA
> 60 1200
> 69 1600
> http://www.spl212.com
>
> ----- Original Message -----
> From: "Adam Bradley" <ambradley@yahoo.com>
> To: "Chianese" <chianese@sprintmail.com>;
> <datsun-roadsters@autox.team.net>
> Sent: Saturday, September 08, 2001 6:43 PM
> Subject: Re: Anti-backfire valve
>
>
> > The durability and longevity of smog pumps notwithstanding, doesn't
> > combining fresh air with hot exhaust exiting the engine cause some
> of
> > the unburned gases to ignite in the exhuast, creating cleaner
> exhaust?
> >
> > At least, that's what my service manual says. I realize it may not
> be
> > a big difference and that your car may be able to beat the ppm
> > requirements without it (which are adjusted upwards for wear & tear
> > already), but I believe there's more involved than dilution.
> >
> >
> > --- Chianese <chianese@sprintmail.com> wrote:
> > > Those of us old enough to remember 1968 and the first air
> pollution
> > > rules
> > > will agree with Tom.
> > >
> > > In all its wisdom, the government mandated emission limits in
> parts
> > > per
> > > million. It didn't take the engineers at most car companies to
> > > figure out
> > > that you just add more millions by injecting air into the exhaust
> to
> > > dilute
> > > the CO and NOx coming out of the engine. Unless you have a
> catalytic
> > > converter or high temperature reactor after the exhaust manifold,
> > > injecting
> > > air does nothing to the QUANTITY of pollutants leaving the
> engine.
> > > It only
> > > changes the RATIO of pollutants to inert gas.
> > >
> > > Once the Feds realized their mistake, It only took a year or two
> > > before they
> > > switched to measuring pollutants in parts per MILE. Air pumps
> > > disappeared
> > > instantly and catalytic converters entered the picture.
> > >
> > > You can remove all that plumbing, valves and the pump without
> feeling
> > > like
> > > an ecological pariah; the car will put out the same quantity of
> CO
> > > and NOx
> > > regardless of the concentration in the exhaust pipe. In fact,
> since
> > > you
> > > don't have to expend power to run the air pump, you will actually
> > > pollute
> > > less by removing it.
> > >
> > > Rick Chianese
> > > Orlando, FL
> > > SRL311-14035
> > >
> > > _______________________________________________________
> > >
> > > Alas, I love clean air... but a well tuned up roadster, with the
> > > earlier SU needles, can run pretty clean without the air
> injection
> > > set up.
> > >
> > > Cheers,
> > >
> > > Tom
> > > ________________________________________________________
> > > Hi List,
> > >
> > > Does anyone have a spare anti back fire valve that they would be
> > > willing to
> > > part with?
> > >
> > > Thanks
> > > Deena & Joe
> > > 69 1600
> > > Westmont, IL
> >
> >
> > =====
> > Adam
> > '70 1600 SPL311-28181
> > http://www.picturetrail.com/abend
> > Get email alerts & NEW webcam video instant messaging with Yahoo!
> Messenger
> >
>
=====
Adam
'70 1600 SPL311-28181
http://www.picturetrail.com/abend
Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger
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