Octane on 17' GT

[Wanka]

I have been reading posts on this forum and somewhat confused on what octane is needed for the 5.0. In my manual it says 87 octane and it seems a lot of people are using higher octane without a tune.
I always understood that using higher octane than what the engine was designed for was a waste of money with no advantage.

I would appreciate it if somebody could clear this up for me. Here in Canada to go to 91 octane is almost 20 cents per litre more than 87, which can add up. However if there is a performance advantage it may be worth it.

Thanks...

 

[UAmach1]

The way modern ECU's work(after 2005 or so) is that they can use 87oct just fine. Benefit is it saves the driver money. When it detects a higher octane it will advance timing and produce more power. Benefit is more performance.

 

[jacknifetoaswan]

I'm fairly certain that my 2016 GT calls for 93 octane, but almost all modern engines, especially those with high compression, have knock sensors. If you put gas in with a lower octane, the knock sensor will identify it, then pull timing to resist detonation. You'll end up with less power than the advertised 435, but your engine will be safe.

JR

 

[ghostnote]

On a stock tune, I see very little difference between 87 and 93. On a blind test, I'm sure I wouldn't be able to tell the difference.

By the way, the owner's manual specifically says there's a 1% power difference between those two fuels. on 435, that's less than 5hp. And when you factor in the 15-20% difference in price, well, premium really makes little sense. In my case, driving my GT about 6k miles per year, the difference is about $150.

On a tuned car, I'd imagine the difference is obvious.

 

[jasonstang]

There is a dyno chart showed that even peak power is only 1% difference on stock tune, the mid range difference is about 20-30hp because how the stock tune is utilizing the extra octane around mid rpm range not at the peak.
Of course there is a difference between 87 and 91. Unless you are running a fixed timing and cam engine that is tuned for 87 only, there will always be some increase in performance and efficiency using higher octane. Whether it's worth the extra money or not is mainly personal choice.

 

[sonicc]

If I'm driving my car to work 5 days a week, I just fill up with 87. If I'm going for a cruise/track event/etc. I use 93.

 

[jasonstang]

If I'm driving my car to work 5 days a week, I just fill up with 87. If I'm going for a cruise/track event/etc. I use 93.

idk how you drive but I use all the rpms on daily basis.

 

[sonicc]

idk how you drive but I use all the rpms on daily basis.

i don't live my life 1/4 mile at a time

 

[jasonstang]

i don't live my life 1/4 mile at a time

Then what's the point of buying a Mustang?

 

[Chameleon]

87 is fine. 93 if you go with a tune.

 

[sonicc]

Then what's the point of buying a Mustang?

great looks
great handling
435hp
nice interior
was cheaper than porsche 911/bmw m3

 

[beefcake]

87 is fine, but like they said, 93 will maximize the power.

if you da tuner, at least 91 is what i would run

 

[texasboy21]

My car feels like a dog below 5K RPMs on 87, and the gas mileage suffered as well.

It equates to a few dollars a fill up difference, so why NOT use 93?

 

[AlmostFamous]

There is a dyno chart showed that even peak power is only 1% difference on stock tune, the mid range difference is about 20-30hp because how the stock tune is utilizing the extra octane around mid rpm range not at the peak.
Of course there is a difference between 87 and 91. Unless you are running a fixed timing and cam engine that is tuned for 87 only, there will always be some increase in performance and efficiency using higher octane. Whether it's worth the extra money or not is mainly personal choice.

This. There's a noticeable difference in mid-range power between 87 and 93 octane. There's another chart comparing 91 and 93 octane, and there was no power difference throughout the powerband. If you want maximum power on the stock tube, you'll need 91 octane or higher.

 

[GTRacerX.]

Fast & Furious

i don't live my life 1/4 mile at a time

I do Whenever I find a nice long road with no traffic or side streets -
Am giving my Stang some exercise. ;)


FYI: I use 93 in my Mustang since day one.