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I have run two tanks now and I think I can tell a difference. Maybe it's suggestive thinking but I think the car feels quicker.
 

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DO NOT run premium gas. It is a waste of money, and will cost you power. Believe me, its all in your head.

Ford and my dealership recommend 87 octane for the Bullitt.

The ONLY reason you need higher octane fuel is to prevent detonation in higher compression and turbo-charged engines. Higher octane fuel burns slower, therefore does not detonate as quickly under higher compression. In a normal compression engine the 87 octane will give a more powerful, quicker explosion than 93, etc.

Hope this helps,
 

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Back to 87 for me!

Thanks, it must be just loosening up.
 

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Well, I didn't know that!! I've been running 91 in it since I got it!!! What a relief that it might actually be better to run a lower octane gas. Especially with today's cost of giving a limb for a tank. =op
 

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The first tank I put it was 92 Octane, after that I went to 89, then to 87. I've been running 87 since. Last week I put in a tank of 92 since gas prices were down. It felt siginificantly LESS powerful. I'm going back to 87.
 

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bwcobra15 is right, premium is a waste of money. As he said, high compression is usually the only reason to run a higher octane (at least, on a factory stock motor) & our 4.6 only has around 9.5:1 compression (I can't remember the actual rating). As a comparison, I own a 1970 Monte Carlo with a 402 with 10.25:1 compression & I rarely run anything other than 87 octane. The only time I notice a power difference is on cool mornings or evenings with little humidity. So, if a high compression, 30 year old big block runs fine on 87, so will our new small blocks.
 

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I have always run 92 in the past but not for the octane rating but because of the cleaner fuel. NOW before you go nuts let me finish. A buddy of mine is a big shot at a convenice store, (Won't say which Brand) and they always have trouble with the managers stealing gasoline money and dumping ANYTHING liquid back into the tanks. Usually they do not mess with the higher octane because they figure the people purchasing that, might notice a difference and call them on the bad gas. Bad milk is a favorite and of course the plain ole water works also. For me I am going to wait till after like 3000 miles and then compare gas mileage between the different octanes and see if it goes down or up or no change at all.
 

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Good post guys.....thx for the info.

I have been running 94 Octane up here in Canada but I am starting to wonder now that you have posted all of this info. I will try a few tankfulls of the other and see what happens.

Hey if it works the same, then by all means.....that is the way to go! I just figured that the higher octane stuff burned a bit cleaner.

Paul G.
 

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I've always thought the higher the octane the better. However since owning the Bullitt and experimenting I have found it runs slugish on 93 and gets up and goes on 87. What a deal it's cheaper and runs better. I'm staying with the 87 octane.
 

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Yup....I was all set to put in another tank of 94 octane.

Hey....the money I save will now be put to a mod perhaps!

Thx Buds!

Paul G.
 

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Yep, with our compression ratio (9.5:1 is correct), regular fuel works fine. Higher octane fuel has greater resistance to pre-ignition, meaning harder to light off. This translates into pooer fuel milage and probably less power on our stock motor. Now, up the compression ratio or go forced induction, and higher octane is a must.

Brian
 

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If you are worried about clean burning gas or fouling plugs and injectors, just take the money you save on 87 octane and put in a can of injector cleaner every 5 tankfuls. Will keep everything clean and still cheaper than the higher octanes........
 

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Ok......hold on a second here Buds....

I realize when I had my Lightning, it was supercharged and thus I needed to use premium for it.

However, I remember with my 98 Z28 there were several fuel map tables in the cars ECM that would be used depending on the type of fuel that you were using.

Since the Mustang has a similar coil on plug system, then wouldn't the computer automatically adjust the timing and spark based on the fuel you were using? By this I mean, the computer would sense the octane of the fuel you were using and if it was premium, it would advance the timing and spark, thus giving you more power.

Any thoughts?
I am just trying to find out myself....

Paul G.
 
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