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Re: New V6 Posted by Ian Glenday [Email]  (#95)  [Profile/Gallery]
(more from Ian Glenday) on Thu, 22 Sep 2005 15:24:44
In Reply to: New V6, Timmydou, Thu, 22 Sep 2005 13:13:29 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Sophisticated 2.8-liter V6 Turbo
The 2.8V6 Turbo has a 60º vee-angle between its cylinder banks for perfect balance and combines excellent multi-valve refinement with outstanding performance. The all aluminum construction provides a light and compact architecture, well suited to its transverse, front-wheel-drive installation in the Saab 9-3.
The cylinder heads, each with double chain-driven overhead camshafts operating four valves per cylinder, are of high specification aluminum and unique to this turbocharged application. The design ensures enhanced heat resistance under 85 bar cylinder pressures, as well as minimum maintenance costs.
Also unique are pistons with hard anodized ring grooves for durability and under-skirt oil jet cooling, together with steel con-rods that are strengthened by sinter-forging, a process that involves molding metal in a powered form. The exhaust valves are filled with sodium to further enhance cooling. The cylinders have cast iron liners and a bore/stoke of 89.00 / 74.8 mm.
For improved engine breathing, variable cam phasing on the inlet side is electronically controlled and hydraulically actuated, allowing continuously variable adjustment through 50º of crankshaft rotation. On the road, this translates to a more flexible power delivery and better fuel economy under different engine loads.
A die-cast aluminum oil sump is designed to increase structural stiffness and the strong, four-bearing crankshaft is made from micro-alloy forged steel, a specification more commonly seen in competition performance or diesel engines. Together with a dual-mass flywheel, these elements further reduce unwanted noise and vibration, ensuring smooth and refined performance.
The twin-scroll, water-cooled Mitsubishi TDO4-15TK turbocharger, operates at 0.6 bar maximum boost with intercooling and an integral by-pass valve. It is mounted centrally above the transmission and fed by both banks of cylinders. The use of two separate inlet tracts, one for each cylinder bank, separates the exhaust gas pulses, improving gas flow, reducing energy losses and raising turbocharger efficiency. The turbine wheel is made from a special high-grade steel alloy, commonly used in the turbocharged engines of world championship rally cars, which is resistant to erosion, cracking and creeping under high temperatures and centrifugal forces.
Also unique are double-skin exhaust manifolds, which are hydroformed with stainless steel liners to improve cold start emissions by minimizing heat absorption to the manifold. Air injection into each manifold for up to 30 seconds after a cold start also helps the central pre-catalyst, positioned upstream of the main catalytic converter, achieve 'light off', its effective working temperature, as early as possible.
The 32-bit engine management system, with software calibrated specifically for the Saab 9-3 application, utilizes a torque-based engine control strategy and direct coil-over-plug ignition with a robust engine-mounted control unit. Ignition timing, fuel injection, turbo boost pressure, air mass measurement and the throttle setting are all key engine functions controlled by the software.
The sophisticated control strategy is designed to deliver smooth performance in all driving conditions. The system works with the vehicle’s transmission to modulate torque, providing stirring performance and excellent engine response. The system can also limit torque in low-traction conditions, helping provide confident, sure-footed driving. Variable fuel pressure further contributes to smooth idle and driving characteristics.
For driving comfort, control of the electronic throttle through the movement of the accelerator pedal is programmed to be sensitive to different driving conditions, with greater pedal movement introduced at lower vehicle speeds, such as when maneuvering or parking. At low engine speeds, the engine control system also brings the turbo in quickly by momentarily opening the throttle slightly more than requested by the driver.
The 2.8V6 Turbo is available in two power configurations. The 250 bhp (184 kW)/350Nm engine is exclusive to the top-of-the-line Aero model and a 230 bhp (169kW)/320Nm version is offered in Arc and Vector variants. In both, maximum torque is generated from just 1,800 rpm all the way to 4,500 rpm, with 90 per cent of this value available from an exceptionally low 1,500 rpm.
Impressive on-the-road performance is typified by a superb low-speed engine response, attributable to the careful programming of the engine management software and the increased engine capacity. Under a full throttle load at take-off or low engine speeds, 90 per cent of maximum acceleration is delivered within one second.
The fast, but controlled, torque build-up immediately above the 720 rpm idle speed (zero to 100 kph in 6.9 secs and 80-120 kph in fifth gear in 8.5 secs for the 250 bhp/ 184 kW engine) is delivered with a turbine-like smoothness. On the top-of-the-line 9-3 SportCombi Aero, fitted exclusively with the 250 bhp (184 kW) engine, careful tuning of the twin sports exhausts downstream of the main catalyst adds a distinctive, exhilarating engine note.
Overall, the result is a high level of performance and six cylinder refinement that perfectly complements the SportCombi's superb chassis dynamics, giving a truly rewarding, fun-to-drive experience.
_______________________________________ Ian 1959 93b 1967 96V4 1968 99 1974 99L 1988 900S 1988 900 1994 900S 1996 900S 1999 9-5SE, 2.3lpt 1995 9000 CSE 2006 9-3SC, 2.0T
, Thu, 22 Sep 2005 15:24:44 <-- Viewing This Message, Thu, 22 Sep 2005 15:23:32
, Thu, 22 Sep 2005 19:02:47
, Fri, 23 Sep 2005 02:59:01, Fri, 23 Sep 2005 07:12:48, Fri, 23 Sep 2005 08:23:15, Thu, 22 Sep 2005 15:21:04, Thu, 22 Sep 2005 15:21:39
, Thu, 22 Sep 2005 15:19:04, Fri, 23 Sep 2005 11:53:01, Fri, 23 Sep 2005 08:53:11, Thu, 22 Sep 2005 14:36:33, Thu, 22 Sep 2005 15:00:53
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