I had to re-read Tim's note. I think you are correct. It does pump air into
the exhaust helping to combust unburnt hydrocarbons. Now, here's a new
question. Does this increase exhaust backpressure? If so, there may be some
efficiency lost from this.
> -----Original Message-----
> From: Eric Conrad [mailto:conrade2@msn.com]
> Sent: Saturday, November 23, 2002 10:09 AM
> To: Tim Hutchisen; Hugh Fader; 'Graham McMicken'; 'Triumphs'
> Subject: RE: Emission Control
>
>
> Tim, et al,
> With all due respect, I have to take issue with your comments
> regarding the
> air pump. Having restored a '76 TR6 to as close to original
> as possible, I
> can confidently say that the air pump did not introduce fresh
> air into the
> cylinder. Rather, it introduced fresh air into the exhaust
> manifold to
> allow full burning of any fuel vapor or hydrocarbons escaping
> the cylinder.
> This is why the exhaust manifold temperatures of an engine
> with an air pump
> is much higher than those cars without the air pump.
>
> I have disabled my air pump by removing the belt and adding a
> new (fresh)
> check valve to keep the exhaust fumes from heading back
> toward the emission
> control equipment. The TR6 runs better, and a little leaner
> (better gas
> mileage) with the air pump disabled. Also, to address a
> comment by Hugh
> Fader, the fan belt running the air pump is a very short
> belt. The beauty
> is that it only runs the air pump, so removing it doesn't
> affect any other
> engine components.
>
> I will entertain comments counter to my feelings.
>
> Eric
> '76 TR6 (CF52678U)
>
>
> [tim hutchisen wrote:]
> The air pump will _not_rob valuable horsepower a whole
> lot. It's job is
> to provide fresh air into the cylinder to help the burn of
> hydrocarbons and
> carbon monoxides. It helps in the efficiency of the flame
> front inside the
> cylinder. (Read: better fuel economy). It also reduces the temperature
> inside the cylinder. So...
> remove the air injection system if you want to:
> 1.) pollute the atmosphere more 2.) get worse fuel economy
> 3.) shorten the
> life of your engine and 4.) create _more_drivability
> problems due to rich
> A/F mixture.
>
> <<snip>>
>
> Removing emissions systems usually result in an increase
> of drivability
> problems and decreased fuel economy as a whole. It is a false
> perception
> that these systems rob horsepower. It was the lower
> compression ratios that
> robbed the horsepower through the 70's, not the emission
> systems. Lower
> compression ratios were the easiest way to meet the strict
> emission mandates
> set in the decade of disco. The engineering had not caught up with the
> mandates at the time in regards to cleaner running engines.
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