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Many reasons why it is done this way
Posted by Ravi [Email] (more from Ravi) on Thu, 18 Dec 2003 10:32:09
In Reply to: Question on Improving Viggen Throttle Response, Bonez, Wed, 17 Dec 2003 07:26:18
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The slow return to idle is done for 4 reasons (at least).
(1) Emissions as others have explained. The old troublesome dashpot in the C900 did the same thing. Problem was it's hydraulics failed so the throttle snapped shut within a couple of years of ownership so everyone has forgotten what it was supposed to do.
(2) If the throttle snaps shut at high boost, the turbo can surge into a bad part of the compresor map. The Bosch BOV valve has a slow response and so the throttle valve has to match the BOV opening.
(3) Keeping the revs up between shifts. Auto mags used to complain that the boost dropped between shifts (not helped by the rubbery gearbox). So Saab forced the revs to stay high a split second longer to allow the boost to stay on boil. That was important with the turbos they used to use, less of an issue now, particularly on the 9-3SS Linears since that turbo spools up really fast.
(4) Saab had relatively slow shifting automatics for a long time and the slower return to idle helped the slushboxes produce smoother shifts.
-Ravi
posted by 198.20.4...
Posts in this Thread:
- Question on Improving Viggen Throttle Response, Bonez, Wed, 17 Dec 2003 07:26:18
- Many reasons why it is done this way, Ravi, Thu, 18 Dec 2003 10:32:09 <-- Viewing This Message
- Re: Question on Improving Viggen Throttle Response, RobInfo, Thu, 18 Dec 2003 10:21:20
- throttle delay in closing is more than anoying..., MTAERO
, Wed, 17 Dec 2003 22:32:46 - That is a feature in the T7, AdamB
, Wed, 17 Dec 2003 18:31:58 - Re: Question on Improving Viggen Throttle Response, Dean, Wed, 17 Dec 2003 08:56:30
- Re: Question on Improving Viggen Throttle Response, ckpaden, Wed, 17 Dec 2003 07:57:45
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