Date: 23 Jun 2004 12:13:51 GMT From: Dave Hinz <DaveHinznospamcop.net> Subject: Re: BMW or Saab Convertible
On Wed, 23 Jun 2004 06:36:24 -0400, Fred W. <Fred.Willsnospampam> wrote: > > While the lierature says "unleaded premium", remember that these cars are > made to run all around the world. US Mid grade (89 AKI) is fine for most > BMWs. The ECU's will retard the timing just like on the SAABs. The only > difference is the SAAB will also limit boost if it detects pinging, so your > loss of power when using lower octane fuel is greater in the SAAB. The ECU that Saab has used for quite a while now, will back off spark timing, or boost, or both, depending on a number of factors. It's all mapped to find the optimal output given the current predetonation situation. It'd be interesting to see torque curves for several engines, with different grades of gas, to see just how good they do. The only torque curves I've ever seen (for anything) don't show a comparison of that sort, but I'd love to see it. Anyone with a Dyno want to do a bit of experimenting?