Some Effects of Engine-Fuel Variables On Exhaust-Gas Hydrocarbon Content 550280
PROPER maintenance and engine design can do much to reduce exhaust-gas hydrocarbons, the authors say. This conclusion is based on mass spectrometer analyses of engine exhaust from 163 passenger cars, most of them customer-owned, and 8 public-transit coaches, operated at idle, part throttle, and simulated deceleration.
Mixture ratio proved the most important engine-fuel variable affecting hydrocarbon losses at idle; thus the V-8 engine, idling best on a leaner mixture, has lowest hydrocarbon losses.
Manifold vacuum had the most effect during simulated deceleration. Since this depends on engine speed, automatic transmissions and the new lower rear-axle ratios are helpful.
None of the engine-fuel variables tested had any effect at part throttle. Type of fuel and engine type (gasoline, diesel, or LPC) showed no significant influence on hydrocarbon content throughout the tests.