NORCROSS, Ga. -- With the introduction of the all-new 900, Saab has completely reverted to its original design formula for transverse engine orientation, first introduced in the Saab 92 45 years ago. The 1994 900 follows the successful Saab 9000 design, which offers maximum packaging efficiency and space utilization, and superior crashworthiness.
Both the 1994 Saab 900 S and 900 SE are powered by advanced, multi-valve engines--a 2.3-Liter, naturally-aspirated, four-cylinder is standard on the 900 S, while the 900 SE features the first six cylinder engine in Saab history. At 2.3-Liter, this is the largest four-cylinder ever offered in a Saab 900--increased from 2.1-Liter. The six is configured as a narrow-angle, 54-degree "V."
Saab's First Six-Cylinder Ever-An Advanced V6
Saab significantly broadens the 900's market appeal with the introduction of its new V6 engine, and consequently attracts an audience it couldn't previously reach.
Standard in the 1994 900 SE, the new V6 is a 24-valve design with a narrow cylinder angle of 54 degrees between banks. It includes an asymmetric valvetrain that makes it one of the most compact multi-valve engines in the world, and features a short block made from 100-percent, recycled cast iron. The four-cam engine is configured with light alloy, twin-cam heads and asymmetric valve angles to reduce width. The camshafts are belt-driven, and act on bucket-type hydraulic cam followers for reduced noise, lower service requirements and improved valve control.
The connecting rods are forged in one piece, then fractured on the bottom end to form the bearing cap. This results in a stronger clamping arrangement, with increased surface area. An oil cooler is located between the cylinder banks, which not only cools the engine oil when hot, but heats the oil when starting from cold.
The powerfully efficient V6 was developed in only 38 months and offers optimum driving comfort and refinement, rather than maximum performance. During the development of the new engine, Saab engineers contributed their special expertise in four-valve technology, advanced testing procedures and industry-leading emission control. These were all-important areas in the joint development process with GM Europe's Technical Development Center in Germany. Saab engineers wrote their own engine management software to ensure good driveability and low emissions under all conditions, and the Saab 900 is the only U.S.-bound application for the new engine. Extensive testing on public roads in Sweden led to many durability improvements, and the Saab approach to attenuating engine noise at its source was also adopted to improve operating refinement.
The result is an engine that has been specifically developed for the new Saab 900. Like all other Saab engines, it provides a high level of low-end torque for maximum flexibility and passing ability. The V6 produces 170 Hp at 5,900 rpm, and 167 ft.-lbs. torque at 4,200 rpm. Engine management is by Bosch Motronic. The V6-powered Saab 900 is easily recognized by its twin-outlet exhaust, along with its distinctive exhaust note.
An electronic Traction Control System (TCS) is incorporated as standard equipment, and is linked to four wheel-speed sensors to detect wheelspin and modulate the engine power under slippery conditions. It includes an instrument panel override switch.
The Saab 900 V6 engine is manufactured by General Motors (Europe) AG at its all-new Ellesmere Port facility in Great Britain.
The Largest Four-Cylinder Ever Offered In A Saab 900
Saab's new naturally-aspirated four-cylinder 900 S engine is derived from the modular design which powers the 9000 series. At 2.3-Liter it retains the same bore and stroke dimensions (3.54 inch, respectively) as the Saab 9000, and provides 150 Hp at 5,700 rpm and 155 ft.-lbs. torque at 4,300 rpm. To package this powertrain in the narrower 900, which also has a smaller turning circle than the Saab 9000, the complete engine/transmission assembly was engineered to reduce overall length. This was accomplished by relocating the oil pump within a drive-belt pulley and by reducing the overall clutch assembly dimensions. That specific change required a substantial redesign of all components, down to the point of stamping identification codes on the flywheel housing bolt heads, instead of allowing them to protrude.
The 2.3-Liter Saab 900 S engine features a cast-iron cylinder block, with an aluminum cylinder head and five main bearings. The twin-cam, multi-valve head includes four valves per cylinder in two rows, inclined at an included angle of 44 degrees. Pentroof combustion chambers and centrally-mounted spark plugs are also specified. The camshafts are chain driven, and act directly on bucket-type hydraulic cam followers for reduced noise, lower service requirements and improved valve control. Saab was the first manufacturer to introduce practical multi-valve engines in series-production sedans, and has since gained considerable experience by further optimizing their everyday advantages for today's consumer. Engine management, as in the V6, is by Bosch
For the first time in a Saab 900, the 2.3-Liter four-cylinder incorporates twin counter-rotating balance shafts, which rotate at twice the crankshaft speed--providing higher levels of comfort compared to its predecessor. The balance shafts reduce the
residual vibration inherent in four-cylinder engines, and provide a similar level of balance to an in-line six. Eccentric weights on the shafts counteract the forces and moments that cannot be balanced by the primar,v moving parts, resulting in a low-vibration engine that is extremely refined and smooth-running.
New Compact Five-Speed Manual Transmission
A new five-speed manual gearbox, manufactured by Saab in Gothenburg, Sweden, is offered on all Saab 900 models as standard equipment. Based on the proven Saab 9000 unit, it has been redesigned for the new 900 transverse engine configuration, and is lighter and more compact. It features more powerful synchromesh cones for the lower gears which results in significantly reduced shift effort. Like the 1994 Saab 9000, the all-new 900 now features synchromesh on reverse for improved operating refinement.
To reduce the overall length of the transmission for the 900 application, Saab engineers used the latest manufacturing techniques to eliminate the previously-required clearance allowed for run-out between each gear. A new manufacturing technique machines each gear and synchro individually, and then laser-welds them together--saving almost one inch in total length. A more compact design of the aluminum transmission case and clutch housing, designed using finite element analysis to optimize stress more uniformly, additionally saved more than another inch. These developments reduced the transmission weight by eight pounds.
Optional Four-Speed Electronically-Controlled Automatic--Another First For The Saab 900
Another first for the all-new Saab 900 is the availability of an electro-hydraulic, four- speed automatic transmission option. It is produced by Aisin-Warner, and weighs no more than the previous Saab 900 hydraulic three-speed unit. It includes a lock-up clutch for the torque converter on third and fourth gears, along with three different driver- selectable shift schedules for sporty, normal or winter driving. The all-new design uses a conventional three-shaft arrangement within a single, light-alloy, compact housing.
Gear selection is controlled by a powerful on-board computer that combines its algorithms with those of the electronic engine management system. This ''cooperationl' results in improved shift quality, better fuel economy, less mechanical stress on the driveline, and automatic diagnostics and information storage. The system is also adaptive. It measures the time taken to perform a shift, then makes automatic internal pressure adjustments when required. As a result, maximum operating efficiency is maintained over long periods in service.
For optimum driving comfort, or when kick-down into a lower gear is required for maximum acceleration, the integrated engine/transmission communication system retards the ignition timing slightly for a few fractions of a second, to reduce engine torque.
The electrically-controlled shift schedules are activated through two push-buttons-- the more frequently used normal/sporty control is conveniently placed on top of the selector lever, while the winter mode control is alongside the selector. The normal driving schedule operates a special set of shift patterns on all four ratios to engage the highest gears as much as possible, while still maintaining good performance and driveability. Above predetermined speeds, the converter clutch engages in third and fourth.
Pushing the button in the top of the selector lever allows the computer to switch to the sport mode, which advances all the shift points to higher engine speeds, including converter clutch engagement, to supply maximum performance under all conditions at any road speed. This schedule is automatically cancelled when the engine is stopped, and the transmission reverts to the normal mode until the sport setting is reselected.
Whenever the driver pushes the accelerator beyond the normal full throttle position, an electric kick-down switch is actuated, automatically selecting the sport mode. This ensures that maximum engine performance is instantly available when needed.
Selecting the winter driving mode activates a special "slippery road" strategy that allows the transmission to start in third gear, to reduce wheelspin. It disengages automatically at speeds above 50 mph. Normal override control is provided in any mode, by using the selector to engage D-3-2-1, as required. The transmission also incorporates protection against misuse, such as downshifting at too-high speed or accidentally engaging reverse gear while the car is moving forward.
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