1985-1998 [Subscribe to Daily Digest] |
![]() | [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 Posted by Ari [Email] ![]() ![]() In Reply to: Re: 110 Octane, TML ![]() ![]() |
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...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
![]() |
![]() |
![]() |
![]() |
![]() |