Date: Sat, 17 Apr 1999 16:25:34 +0200 From: RCS <e9225126nopsam1.tuwien.ac.at> Subject: Re: Higher octane improving performance?
Thatīs true! There is no big difference at our 9000 CSE 2.3i without turbo/APC between the 89 and the 98 octane. But thereīs a huge noticeable increase of torge and power on my 93 900 turbo convertible!!! But , well the ecconnomy... If the car runns better you kick it more... and the consumption will be the same or even higher - depending on your driving style.. - RCS - John Weiss: > If your Saab is late '82 or newer (US spec; I don't know about other > countries), it has some version of APC (Automatic Performance Control). The > knock sensor dynamically adjusts timing and the turbine wastegate. Higher > octane gasoline will allow higher boost on a turbocharged engine, giving > markedly better performance. > > There is probably much less noticeable performance difference on a non-turbo > engine; I always used regular grade gas in my '91 900S. > > There is probably less of an impact on gas mileage. We notice a definite > reduction of mileage (2 mpg or so) in my wife's '98 900 Turbo when using 87 > octane, but no noticeable difference between 89 and 92 octane. It probably > depends on how aggressively you drive -- if the APC sensor has to do its > work more often, it probably will affect mileage more. > -- > John R. Weiss > Seattle, WA > Remove *NOSPAM* from address for e-mail reply > > Andreas van der Wal <andreasnopsamnt:want.spam.cost.se> wrote in message > news:7f7hgf$jlk$1nopsamcola.tninet.se... > > > I have wondered in what way the octane corresponds to the performance of > > the engine. I know that higher octane prevents knocking and therefore > > can tolerate higher combustion which could lead to more hp. The question > > is rather if I one time fill up my car with 95 octane fuel (european > > values) and the next time with 98 octane fuel, how would that influence > > the run of the engine.