What Octane are you using for the 5.0?

[slythetove]

i wanted to switch to 87, but the kool aid drinkers in here scared me into just wasting my money on 93

There is no reason for anyone to be scared or confused by this topic - it's not magic, it's simple science.

The explanation has been listed multiple times in this thread.

Higher octane resists spontaneous combustion better than lower octane. That's it. It is not a power adder in and of itself, and it doesn't guarantee "cleaner" or "better" fuel.

If your car is tuned for 87 then adding 93 will do nothing - this is because the timing set for the compression level only requires 87 to be combusted without pre-igniting.

If your car is tuned for 93 then using 87 can lead to detonation - this is because the tune is aggressive enough (and/or there is enough compression) that the 87 will pre-ignite prior to the expected spark event timing. That costs you power and can lead to damage.

The Mustang GT appears to have the ability to automatically adjust the tune slightly (altering the timing curve quickly upon knock detection most likely) to allow for 87 to run safely, but also to let 93 make maximum power.

That's it. No mystery, no voodoo, just plain facts.

The difference in power may or may not be noticed by an individual depending on their ability to feel changes in the car. Most people wouldn't know the difference (but almost all will claim to feel it!).

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[Vile_the_Bastage]

93 octane. I was already used to paying for premium because I had to with my Subaru, so why go cheap now.

 

[SVTFreak]

The Mustang GT appears to have the ability to automatically adjust the tune slightly (altering the timing curve quickly upon knock detection most likely) to allow for 87 to run safely, but also to let 93 make maximum power.

There is no appear. That's how it works.

On the 3V 4.6, the knock sensors where only a safety device. When they sensed knock, they pulled lots of timing. Many tuners simply turned them off and, with a good tune, it had no effect on engine life. On the 5.0, they are active fine tuning devices. When the computer senses knock, it pulls only small amounts of timing until it no longer senses it. When running 87, knock is sensed earlier and timing pulled earlier than 93. The lower timing level results in a little less power. On the 5.0, if you turn them off or desensitize them, there's a good chance you'll blow it up. It will, within parameters, keep advancing timing, never hearing knock.

I hope that clears up how it works.

As far as who runs what? Some people rather save money than get a few horsepower and thats their prerogative. No need to call them silly or wrong because you don't understand their reasoning. And vice versa is true also.

The guy running 87 with the driver mod will outrun the guy running 93 and can't drive all day long.

 

[slythetove]

There is no appear. That's how it works.

Yes, I realize that - I should have left appears out of that sentence. I'm used to softening my writing for folks.

 

[Barrel]

Tuned on 93 - so generally BP 93 with some octane booster just-in-case.

 

[Hack]

When I first bought my 2011 I ran 93 for a while. Then winter came and I knew I would never miss the power (plus the car will probably never pull timing when it's below 30F outside), so I switched to 87. I never could tell a difference in power between the two fuels and I've never gone back.

I've never put anything but 87 in the 2015. Higher octane is a waste of money in my opinion.

 

[SVTFreak]

Yes, I realize that - I should have left appears out of that sentence. I'm used to softening my writing for folks.

Lol. Sorry. Didn't mean anything by it.

 

[CoyoteS550]

I live in the San Francisco Bay Area, land of crappy gas. Best I can get is 91, and that's what I use.

 

[JimmyTwoTimes]

I live in the San Francisco Bay Area, land of crappy gas. Best I can get is 91, and that's what I use.

Just throw a bottle of this in every time you fill the tank:

http://www.goldeagle.com/brands/104

 

[FiveLiterDreamer]

I used 93 for the first 3500 miles. Now I'm using 87 mainly because the road conditions in Michigan are so crappy I don't see a point in using 93 until summer. haven't noticed a gas mileage difference can't speak to performance since it's snowy and icy.

 

[CoyoteS550]

Just throw a bottle of this in every time you fill the tank:

http://www.goldeagle.com/brands/104

Thanks, was thinking about using an additive. How do you like it?

 

[JimmyTwoTimes]

Thanks, was thinking about using an additive. How do you like it?

It's always run clean and smooth for me every time I've used it.

 

[Tele5.0]

I remember hearing back in the day stuff like this causing the O2s to fail, "burn up" or go bad faster. Anyone know if that is still the case?:shrug:

 

[Tweezy7]

Running Shell and Sunoco 93
Trying to find higher apparently some Sunoco have 94 No Luck in VA so far with that or higher

 

[slythetove]

Lol. Sorry. Didn't mean anything by it.

No offense taken - you're right it's how it works no ifs ands or buts - and people really should know. I hate all the misinformation that goes around in these octane threads.

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