Posted on 01. Mar, 1997 by in 2010-2019


20 Years After, Saab Remains a Leader in Turbo Technology

NORCROSS, Ga. — Twenty years ago, Saab unveiled a revolutionary application for the rather exotic turbocharger: use it on a small-displacement engine in an everyday family car for extra power and low-end torque on demand. Previously reserved for racecars and high- dollar or limited-production sports cars, turbo technology debuted at Saab in a limited run of 100 1977 Saab 99 Turbos provided to automotive journalists in Europe and the United States. Enthusiastic reviews were followed by the regular production models of the 1978 Saab 99 Turbo and the new Saab 900 Turbo a year later.

Saab’s turbo was unique for featuring an adjustable-boost turbo on a small- displacement four-cylinder engine. Rather than use a turbo for maximum output at high speeds, as was common in other turbocharged cars, the Saab turbo enhanced the engine’s low-speed response for quicker acceleration and improved passing power. Other significant turbocharger benefits are lower fuel consumption and reduced exhaust emissions compared to naturally aspirated engines with the same power output. While some naturally aspirated engines use elaborate and expensive induction systems that rely on vacuum to suck air into the cylinders, Saab has found that a greater volume of air can be pushed into an engine over a wider rpm range by the relatively simple exhaust-driven turbocharger. The Swedish automaker continues to be a leader in the production of advanced turbo engines, available on both the Saab 900 and 9000 lines.

Turbocharainq Drives 1997 Ecopower Concept
Saab’s 1997 turbo engines and their exclusive technology are collectively known as Ecopower. Not just a catch-phrase for a few engine features, Ecopower is the Saab development concept for current and future Saab engines — a way of thinking in terms of sensible, yet exhilarating performance, environmental responsibility and a high standard of comfort and driveability. The key elements of 1997 Ecopower technology are turbocharging with intercooler, Trionic engine management, dual overhead camshafts, four valves per cylinder, Direct Ignition {DI), a pre-heated oxygen sensor and catalytic converter positioned close to the engine for quick warm-up.

Ecopower applies to Saab’s full-boost turbos and Light Pressure Turbo (LPT) four- cylinder engines. The four Ecopower engines are the potent 185-hp 2.0L in the Saab 900 line, the award-winning 170-hp 2.3L LPT in the Saab 9000 CS, the 200-hp 2.3L in the Saab 9000 CSE and the impressive 225-hp 2.3L in the Saab 9000 Aero.

The most obvious advantage of a Saab turbocharged engine is increased power. Normally, 30 percent of fuel consumed in an engine goes out in the exhaust as unused energy. A turbo utilizes the exhaust gas energy and returns it into the engine for additional power. For every one horsepower taken from the exhaust by the turbo, four extra horsepower are produced at the engine crankshaft. Compared to a naturally aspirated engine of the same horsepower, a turbo engine is smaller, lighter in weight, uses 12 to 20 percent less fuel, produces more low-end torque and significantly lower exhaust emissions. The natural sound dampening qualities of the turbo itself allow Saab to use the same size muffler as on a non-turbo car, despite the higher power output. Simplicity and cost effectiveness are additional turbo advantages. For a naturally aspirated engine to match an Ecopower engine’s high torque output and low emissions, it would require a combination of these add-on technological features at additional cost: variable intake manifold, tuned exhaust manifold, variable earn phasing, air injection at cold start and EGR (exhaust gas recirculation).

Saab Trionic Features Powerful Microprocessor
The award-winning Saab Trionic engine management system used for Saab Ecopower engines was designed and tested by Saab’s own engineers. Saab is one of the few car manufacturers in the world to develop its own electronic engine management system. The brain of Saab Trionic is a 32-bit microprocessor, capable of carrying out two million calculations per second. Programmed with ideal combustion conditions, the microprocessor simultaneously monitors and adjusts the ignition timing, fuel injection rate and boost pressure. Control is adaptive, which means that the system adjusts all calibration points while taking into account variations in engine parameters, such as temperature, load and even engine wear.

Trionic analyzes the combustion process by using the spark plugs to measure ionization in the cylinders. A weak electrical current is applied across the gap of each spark plug after every combustion stroke. The voltage flowing back to the control unit measures the combustion efficiency in each individual cylinder. The system continually adjusts the fuel quantity, the ignition timing or the boost pressure to ensure each cylinder’s fuel-air ratio is as optimal as possible. The result is a reduction in fuel consumption and exhaust

Individual ignition timing tailored to each cylinder is possit thanks to Saab’s Direct Ignition (DI) system, featuring one ignition coil per spark plug. Introduced on Saab cars in 1985, DI provides up to 40,000 volts at the moment of ignition. The Trionic systems on full-boost turbo engines have an integrated Automatic Performance Control (APC) function, which helps
regulate turbo boost pressure correctly, regardless of fuel quality or octane. APC allows all of Saab’s Ecopower engines to run on regular unleaded fuel. Premium fuel is recommended only for the Aero’s 225-hp engine.

Light Pressure Turbo Is Intetliaent Alternative

Saab’s latest turbo innovation is the Light Pressure Turbo (LPT), introduced on the 1995 Saab 9000 CS. LPT widens the application of turbocharging by shifting the focus of turbos from pure performance to performance assist. Designed specifically to provide strong low-speed torque and a smooth power application, the LPT engine effectively emulates the driving characteristics of a larger-displacement naturally aspirated engine while maintaining low emissions and high fuel economy. Boost pressure is limited to 0.4 bar rather than the sporty full-boost power of 1.0 bar in other Saab turbo engines. Because the boost pressure is fixed at 0.4 bar, APC is not required to control boost pressure. A boost gauge is also unnecessary,
and no turbo badging is applied to the Saab 9000 CS.

Addressing the “Turbo Myths”
As turbo engines developed over the years, the term “turbo lag” became synonymous with turbocharging. Indeed, early turbo engines required several seconds to build full charge pressure. In contrast, today’s Saab turbos utilize a small, low-mass turbine that spools up almost instantly. Boost pressure builds quickly, providing maximum torque on demand — at engine speeds as low as 1,800 rpm on the 2.3L engine in the Saab 9000 CSE and Aero, and 2,100 rpm on the Saab 900’s 2.0L engine. The LPT engine is even more remarkable in its ability to mask the fact that there is a turbo under the hood. Totally integrated into the engine’s power curve, the LPT reduces any perception of “turbo lag” or “turbo kick” to nil. Instead, the driver simply enjoys strong, predictable power at all speeds.

Reliability issues have also haunted turbochargers, but the advent of electronic boost control and water-cooled center housings in the mid 1980s addressed these concerns nearly a decade ago. Today’s Saab turbo is a fully integrated part of the engine, designed and proven to be maintenance free and dependable for the life of the car. Saab’s own warranty analysis shows that a turbocharger is as reliable as other major engine components for as long as the car is on the road (at least 15 years, in Saab’s case). Twenty years after the start of a new epoch in powerplant design, Saab remains as committed as ever to turbocharging for current and future Ecopower engines.

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