Maybe this works better. This is a cut and paste, previous was an
attachment. Sorry if it was unintelligible. I also had a letter printed in
Old Cars Weakley last week.
Bob ADler
June 18, 1999 HMN 26
Terry Ehrich
Hemmings Letters
PO box 256
Bennington, VT 05201
Dear Terry:
NOTES FROM THE CORROSION LAB;
DIESEL EMISSIONS INSPECTION
I recently sent public comments to the New York Department of Environmental
Conservation (DEC) on their proposed "Heavy Duty Inspection and Maintenance
Program". This is a proposed smoke opacity test for diesel trucks above 8500
lbs. GVWR. The test is performed by placing a smoke meter in the exhaust
plume of a truck and accelerating the engine to 80% of its governed speed.
The smoke meter has a light source and photocell, and the amount of light
attenuation due to exhaust smoke is recorded. Cut points are:
1973 and older 70% maximum opacity
1974-1990 55%
1991 and newer 40%
The procedure is explained in Society of Automotive Engineers standard J1667
I read and studied The NY proposal, as well as the text of SAE J1667, and
spoke to a smoke meter manufacturer. Cut points seem reasonable to elucidate
gross polluters.
I proposed removing antique trucks from the test. My reasoning was,
vehicles 25 years old or older may suffer serious engine failure during the
test. Older governors may not control an unloaded engine adequately under
no-load conditions as required under SAE J1667. Many governors work by
limiting fuel pump capacity. This system can work admirably under load but
unreliably under no load, or using only engine inertia as a load.
Accelerating to 80% of the manufacturer's recommended maximum engine speed,
as specified in the test, can cause problems with older vehicles for two
reasons: First, the numbers may not be readily available, and second as any
machine ages, the maximum allowable speed should be decreased. It is
sophomoric to believe under red line is safe, and over red line unsafe.
Owners of older vehicles are interested in maximizing engine longevity. As
speed increases to the descending slope of the torque curve, probability of
engine failure starts to rise. For an older engine, 80% of red line could
already be in an accelerated wear zone, especially under no load. Therefore,
I proposed a rolling emissions inspection cut off of 25 years.
I also explained, it is my belief that exempting 25 year old vehicles from
this inspection will not materially affect air quality as antiques are rarely
driven. Actual vehicle miles traveled (VMT) for these vehicles should be
investigated by DEC to confirm this. I also noted precedent was set when DEC
exempted 25 year old vehicles from the NY gasoline powered emissions
inspection. I reported my comments on that rule in March 95 Hemmings Letters.
I further commented the inspector training program must be sufficiently
rigorous so graduates can accurately correct raw data for the myriad of
variables listed SAE J 1667. A test meter manufacturer said a technician
could be trained in the use of his smoke meter in fifteen minutes regardless
of his educational background. All variables listed in SAE J1667 were
automatically corrected for by the meter's computer. I said technicians
should have an engineering background so they understand what they are doing,
and what the smoke meter is doing. Understanding the 48 pages of formulas
and corrections for ambient conditions in SAE J 1667 takes more than fifteen
minutes to digest.
It is my hope that other Hemmings readers can use this as a model when their
states propose similar rules, as this is being driven by the US Clean Air Act.
Sincerely,
Bob Adler
Adler's Antique Autos, Inc
801 NY route 43
Stephentown, NY 12168
518-733-5749
email Advdesign1@aol.com
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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