Thread: octane rating
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Old 06-13-2012, 03:12 PM
j6harris j6harris is offline
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Engine: 2009-20?? 345ci (5.7L) Hemi V8 390hp 407lb/ft
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Originally Posted by snrusnak View Post
Wow man. Most of the changes that you noticed between those fuels is in your head. Using 93 octane instead of 89 octane on the hemi will not give you any more power or mpg(at any rpm). It will help promote carbon buildup, though. This is assuming it's running the stock tune.

It's been discussed a million times, and there are reasons behind it. The hemi will run on 87 no problem. It will produce slightly more power and mpg on 89. Slightly does mean slightly; switching from 87 to 89 won't give you 50hp so you can beat your buddy's chevy. The difference likely isn't even noticeable to the driver(maybe 5hp?). Anything more than 89 is just throwing money away and promoting carbon buildup, so you'd actually be doing better for the engine and your wallet to put 89 in instead of 93.

Now I will say that I have no idea what oxygenated or non oxygenated fuel I won't comment on that other than I guarantee you didn't doubled your mpg with it...
i never said more horsepower ... your knock sensor automatically changes your timing... octane rating is the rating in which the fuel is resistant to burn.. so if i'm using 93 my timing will be different than if i'm using 87 and thats where the change in acceleration and how the vehicle performs is coming from depending on how hard or not hard i'm driving it... basically at full trottle its firing like it would be at idle because the fuel is able to take the beating and not detonate.. it is noticable.. i physically did all of this myself.. i didnt just read it somewhere and blah blah blah to everyone in the forum.

oxygenated fuel is gasoline that has additives like ethanols.. 90% of fuel in america is oxygenated now

non oxygenated fuel is gas.. it is more efficent than oxygenated fuel but more corrosive. oxygenated fuel is more succeptable to water contamination so non oxygenated fuel is recommended for small engines, boats, and collector cars because of its resistance to moisture. its basically gas like gas was back in the 60s after they got rid of leaded gasoline.

Last edited by j6harris; 06-13-2012 at 03:18 PM.
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