Shane F. Ingate wrote:
> They ran well without all the emissions gear in Blimey and Oz,
> did they not, or were they rough idling pigs?
Well, rough idling is in the eye of the beholder. But
BL was having problems making their cars seem upscale, when
they sounded like chainsaws compared to other cars of
the era. Not inspiringly refined-sounding.
I suppose to a non-enthusiast, back to back test drives
didn't come out in favour of our LBCs. If you have any
of the Brooklands Portfolio books, you won't likely
find any head on comparison that chose a british car
over any other after about 1970. Sad, but true.
And sure, I know we are all thinking "who cares about
non-enthusiasts" but without normal people buying our cars
new there wouldn't be so many out there for us to own today.
> My question about EGR goes unanswered. I know a little of the theory,
> in that the EGR valve allows a little of the exhaust gasses from
> cylinder #5 to cycle back into the intake manifold.
Basically, yep. The drawing area depends on your car, on
a Midget like mine it draws from a section of the manifold
that collects all cylinders.
Essentially, there are times when you don't need power. There
are during cruise and deceleration. The problem is that the
cylinders need to fill with SOMETHING. If you don't let the
cylinders fill easily, there will be a large parasitic
drag to the engine as it tries in vain to fill the cylinders
with air through the closed butterly.
As well, overrun is a tricky engine condition to perform
complete combustion. Engines will consume fuel-air that
they don't combust very well during these circumstances,
which both wastes fuel and produces emissions.
During these situations, manifold vacuum is high. An EGR
valve is triggered from this high manifold vacuum, which
opens a path for exhaust gas to be sucked into the cylinders.
Since exhaust gas contains more or less no oxygen and
no fuel, it is essentially inert. So the fuel/air ratio
in the cylinder can stay about right, but with much
less of either.
> The cool combustion chamber temperature of coures means less hp.
Well, the cool combustion chamber is only during
certain circumstances, none of which are times that
you require horsepower. During acceleration periods,
the EGR valve is just along for the ride.
When working, EGR is free. It can also help with a nice
smooth cruise, and also can help mileage when working.
> So for those folk who have a bad EGR valve, should they continue
> with their bad valve (and rough idle, pinging, overheating, loss of
> hp and high emissions) or should they take it off, and return the car
> to its "original" (read "as designed for the British and non-American
> markets) form? It may even run a little cleaner, too.
Well, I can answer what I did. My EGR valve is broken,
so I have it disabled. It's still installed, but the
vacuum line is pulled so it doesn't open. It didn't reliably
close before, which was nasty.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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