[Main 9000 Bulletin Board | BBFAQ | Prev by Date | Next by Date | Post Followup ] Member Login / Signup - Members see fewer ads. - Latest Member Gallery Photos Waste of money Like This Post: - Subscribe to Daily Digest for this Bulletin Board Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Fri, 8 Aug 2008 05:01:32 In Reply to: Re: 110 Octane, TML [Profile/Gallery] , Thu, 7 Aug 2008 21:33:26 Alert me when someone posts in this thread: Members see ZERO ads on the bulletin boards and get more feature. - Help Keep This Site Online - Signup

The octane rating is the measure of a fuel's resistance to predetonation - knock. It doesn't contain any more energy - in fact, the anti-knock additives usually reduce total energy slightly. It doesn't burn any hotter. It doesn't clean out the injectors - in fact, racing fuel often contains fewer cleaners than normal fuel.

Your engine needs a certain octane to make full power. Below that octane rating, the engine will start to knock, and the ECU will adapt by adjusting fuel flow, ignition timing, and if a turbo, boost. That reduces power. If you put in fuel more resistant to knock (higher octane) than you need, the ECU doesn't keep turning up the wick - it goes to the normal setting and stays there.

So if your car runs happily on 89 octane, the running 90, 95, or 100 will get no extra power.

So what's the advantage of high octane fuel? If the engine needs it. Crank up the compression ration, and you need higher octane. Crank up the boost, and you need higher octane. You'll see 100 octane used in older muscle cars where the compression ratio was high, or in modified engines where between shaving the head, piston, crank, and cam mods, the compression ratio is much higher than stock.

You want to give your baby a treat? Use the money for a bottle of Techron. Or replace that 3 year old thermostat, flush the cooling system, flush the brake lines. Really boring stuff.

posted by 76.243.12...

• 110 Octane, 96Aero, Thu, 7 Aug 2008 21:12:29
  • I did it for my car's 111,111 milestone day..., saab4life9k, Thu, 7 Aug 2008 21:41:53
  • Re: 110 Octane, TML , Thu, 7 Aug 2008 21:33:26
    • Waste of money, Ari , Fri, 8 Aug 2008 05:01:32 <-- Viewing This Message
      • Re: Waste of money, oldsaab, Fri, 8 Aug 2008 19:04:24
        • Higher octane fuel is formulated to have more energy..., Street , Sun, 10 Aug 2008 15:51:14
          • I think higher octane is formulated to burn slower., RayF, Wed, 20 Aug 2008 15:27:00
        • With higher prices, over here >, Bill Davies, Sat, 9 Aug 2008 05:22:17
      • Had an old Camaro that needed it, adamK, Fri, 8 Aug 2008 05:08:30
        • Re: Could it be tuning?, aaron, Fri, 8 Aug 2008 17:10:00
          • A little tweaking, adamK, Mon, 11 Aug 2008 07:06:30
          • A little tweaking, adamK, Mon, 11 Aug 2008 06:32:10
    • Only if you are modified, adamK, Fri, 8 Aug 2008 04:58:40
      • Re: Only if you are modified, jdlincoln , Mon, 11 Aug 2008 17:38:54

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• Prev by Date: Only if you are modified, adamK, Fri, 8 Aug 2008 04:58:40
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