octane

[93rev2sev]

Octane for Steve.

Lower octane gasoline has a tendancy to detonate(knock) in 9.5 to 1 compression ratio engines. Worn 9.5 compression ratio engines have lower compression than 9.5 to 1(cause they are worn - duh) making detonation less likely. The SHO has a knock sensor that will retard the timing if it senses detonation-stopping detonation and lowering your horsepower rating. 93 octane pays for itself in fuel mileage. I've done the math.
Also:
As the price of Gas goes up...the difference between 87 octane and 93 octane remains the same 20 to 30 cents/gallon. This make 93 octane an even better value.

Put what you want in YOUR car...mine gets premium.

 

[sdpatt]

I tried to save a few bucks on my daily 98-mile commute by running on 89 octane gas. After about 10 tanks ot the 89, the sound of the signature pinging at almost every throttle tip-in made me cringe. Then I began to notice the engine surging at 1500-2000 rpms as I was constantly changing speed and gears during the evening rush hour traffic slog.

With the 89 octane fuel in combination with the 30+ days of 100+ degree temperatures here in Dallsa/Fort Worth, I had noticed a fluttering power loss as I tipped in the throttle to accelerate at highway speeds. It almost felt like a misfire, but I suspect that it was only the EEC dialing back the ignition advance in response to the pinging.

An inspection of the plugs found gaps in the .065" range on the Motorcraft AGSP32PPs that were installed at 268,000 miles. Regapping the now platinum-less plugs resolved the surging. Returning to the 93 octane premium corrected the pinging. The throttle tip-in at highway speeds was back to the normal surge of smooth power that lets the SHO find its place in the open lanes.

89 octane? Not for my SHO.

 

[1slickRED89]

Lower octane gasoline has a tendancy to detonate(knock) in 9.5 to 1 compression ratio engines. Worn 9.5 compression ratio engines have lower compression than 9.5 to 1(cause they are worn - duh) making detonation less likely.

worn rings and other wear items allow more oil vapor into the PVC gasses (increase oil usage, it goes somewhere), oil vapor in the PVC reduces the octane of gasoline drastically.

 

[Ultymte]

To recap:

:type: :cuss: :snap:

:shakehead

 

[doclees]

Has anyone have cel come on due to octane issues?

 

[bobreimer]

There's a lot of debate about octane, but mine runds noticeably better and makes more power on 93 octane.

 

[dantheman68]

I said "IF I WERE YOU I WOULD RUN 93. Maybe 89, but never 87." That means I never run 87 octane. Because that's what I choose to run, and no it's not a waste of money. I have read most of the threads on the subject too so I am aware of that also. I suggest you educate yourself on the fact that the words "if I were you" are totally different then "you absolutely must"... Wow! you know what octane ratings mean? You must be the smartest guy ever!!!

But if you were him, you wouldnt have YOUR car, you'd have his car... and you would be asking if it was okay to mix octanes, which IS OK.... he never said anything about putting 87 in his car... you dont have to get defensive, nobody is attacking you. IMO you freaked out for something that didnt even belong in this thread anyway...