SAAB ENGINE DESIGNED ''CLEAN'' AND ECONOMICAL FROM START
Lambda Guard Allows both Good Mileage and Clean Emissions in Western Areas
ORANGE, CONNECTICUT -- The engine currently used in the Saab 99 cars was designed in the middle 1960's, when the demand for clean exhaust emissions was already becoming a very important factor in automotive engine design. The four cylinder overhead camshaft engine was designed with these requirements in mind right from the beginning. Since that time the regulations have become increasingly stricter, and the Saab engine, thanks to its original 'clean' design, has been able to meet a1l of the regulations with only minor modifications.
One important factor assisting in this accomplishment is fuel injection, which has been used by saab since 1971. In 1975 the original electronic fuel injection system was replaced with the simpler and easier-to-service Bosch Continuous Fuel Injection System (CI System), which together with a number of other modifications has enabled Saab to continue to meet the Federal exhaust emissions requirements without the use of a catalyst through 1978. The only major engine changes on ''Federal'' 1978 Saabs is the introduction of a new two-part exhaust gas recirculation system and a breakerless ignition system. The ''Federal'' version of the 1978 Saab engine develops 115 horsepower (SAE net) and 123 ft. lbs. torque. The compression ratio is 9.25:1.
1978 Saabs sold in 1he Western and Rocky Mountain states have been equipped with the revolutionary new exhaust emissions control system with three-way catalyst since 1977. This system, called Lambda Guard, has been widely hailed by both officials and press especially since it allows for excellent fuel economy and clean exhaust, without any traceability penalties.
The system is based on maintaining as close to a perfect, or stoichiometric, air-to-fuel ratio as possible. (The Greek letter Lambda is a technical symbol for the air-to-fuel ratio). Because of the perfect air/fuel mixture, 1he three-way catalyst is capable of both oxidizing the engine's output of CO (carbon monoxide) and HC (hydrocarbons) and reducing the NOx (Nitrous Oxide). Most catalytic converters are only able to accomplish the oxidation process, and thus cannot reduce the NOx contents.
The close air/fuel ratio control is maintained by a modulating valve incorporated into the engine's f uel injection system. This valve is controlled by an electronic control unit which receives input from an oxygen sensor in the exhaust manifold. The sensor ''reads'' the oxygen content in 1he exhaust and ''reports'' this to the electronic control unit, which in turn constantly adjusts the modulating valve to maintain as close to perfect air/fuel mixture as possible.
In addition to its clean exhaust and fuel economy characteristics, the oxygen sensing ability of the 1977 Saab with Lambda Guard is such that it is self-compensating for changes in altitude. Thus 1he 1978 Saab will run as well -- and nearly as clean -- at high altitudes as at sea level.
With the Lambda Guard and the three-way catalyst, the 1978 Saab 99 engine develops 110 horsepower (SAE net) and 119 ft. lbs. torque. The compression ratio is 8.7:1.
The fuel economy information, as compiled by the U.S. Environmental Protection Agency (EPA) reports the combined highway and city fuel consumption for the ''Federal'' 1978 Saab models at 23 mpg for manual transmission cars and 21 mpg for automatic transmission cars. The corresponding figures for Saabs with Lambda Guard is 25 mpg for manual transmissions and 23 mpg for automatics.
Lambda Guard equipped 1978 Slabs will be available in November through some 70 Saab dealers in the states of California, Oregon, Washington, Idaho, Utah, Colorado, Arizona, Alaska, Montana, Nevada and Wyoming.