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Will I see a difference (performance, economy, etc) from using a higher octane fuel (94) in a carb'd and cat'd motor? This is in regards to my old stock Bonneville 3800.

She was rated at 110hp and 190tq from the factory.

---------- Post added at 10:45 AM ---------- Previous post was at 10:40 AM ----------

And is running it hard on occasion beneficial for cleaning out carbon build up?
 

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Theoretically you shouldn't, since the purpose of the higher octane fuel is to prevent knocking from higher compression engines. If your car is designed to run on regular, all the higher octane fuel will do is leave you with a little less money after filling up, I would think. But I'm no mechanic or engineer, so don't take my word as 100% fact.
 

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I would normally agree, but this car doesn't have the complex computers or tuning of a modern fuel injected car. My thinking is that the engine can immediately take advantage of the higher grade fuel and make more from it than regular 87. No retune or reflash necessary.

That's my best guess however. Good chance I may be barking up the wrong tree.
 

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Its a 100hp car. Run regular and don't waste your money unless you start hearing detonation
 

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Regular gas actually has more energy in it than higher octane and is cleaner since it has less additives. The car even that old bonneville has spark knock sensors and will set the spark timing just before detonation for best performance. If it runs bad it probably needs new spark plugs or a can of gas treatment.
 

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The octane rating is the fuel's resistance to spontaneous combustion under compression. The higher the octane rating, the more compression it takes to make the fuel spontaneously ignite. If your car is not high compression you are wasting money. Since higher octane takes more to burn low octane will work better in a Cobalts.
 
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