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My Understanding of the LPT has been based on Posted by Ian Glenday [Email]  (#95)  [Profile/Gallery]
(more from Ian Glenday) on Wed, 29 Jun 2005 22:27:32
In Reply to: If turbo is spooled up all the time,, J, Wed, 29 Jun 2005 07:16:21 Members do not see ads below this line. - Help Keep This Site Online - Signup |
the Saab description of its system which follows my commments. The small turbo is used in the Saab LPT so it spools up quickly resulting in little turbo lag. I believe that the flat torque band from 1800 - 3200 rpm is directly related to the turbo being spooled up all the while the engine is generating power in the torque band. Because of the low boost pressure in LPTs, Saab did not include or see the need for turbo gauges in the first few years of production. To me the turbo is either on or off and an LED could be used to indicate this for an LPT. The affect of the turbo drops off rapidly at 3200 rpm (this is why Abbott modifed the turbo they sell - to provide more boost past 3200 rpm). Saab Master Techs have told me that a complete turbo failure in a 9-5 LPT will result in a very poor running engine. The engine is just not designed to operate without the assistance of the LPT. If my understanding is wrong, please tell me why. Thanks!
"Saab's 2.3L Ecopower Engine
The Saab 9-5's 2.3L Ecopower Light Pressure Turbo engine develops 170 hp at 5,500 rpm. The engine's Light Pressure Turbocharger uses relatively low boost pressures (maximum boost of about 5.8 psi or 0.4 bar) to deliver boost quickly, providing higher torque at low engine speeds. Extra power is put to use only when it is actually needed, providing a comfortable, satisfying driving experience, with responsive performance, low fuel consumption and low exhaust emissions. Strong low-end torque also contributes towards safer passing and more relaxed driving, without needing to frequently rev the engine to high rpm. Because the operating parameters are all controlled by the Saab Trionic engine management system, the performance of the 2.3 liter Ecopower engine has been programmed to develop optimum power with a very flat and broad torque curve. The power curve peaks at 5,500 rpm, while the torque curve is actually a torque plateau-a completely straight line from 1,800 to 3,500 rpm. In fact, over 70 percent of the peak torque value is developed from just above the idling speed to the electronically-governed redline at 6,000 rpm."
_______________________________________ 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
, Tue, 28 Jun 2005 22:23:15, Wed, 29 Jun 2005 22:27:32 <-- Viewing This Message
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