Sponsored

Are we really using 87 fuel?

Aki

Member
Joined
May 11, 2026
Threads
0
Messages
14
Reaction score
12
Location
West Palm Beach, Fl
Vehicle(s)
2026 Dark Horse 6sp
My previous mustang, the 2019 GT, would protest low quality gasoline by way of misfire and hesitation. It taught me to only go for the expensive stuff, so I continue using V-Power only in the DH as well. With the amount I drive, no reason not to.
 

Racer57

Member
Joined
May 14, 2026
Threads
2
Messages
15
Reaction score
43
Location
Illinois
Vehicle(s)
2025 Shelby Cobra
For those that “mached” :) my comment where I said that octane did not create horsepower. Do you know something that Car and Driver doesn’t ? :)

“Raising the octane rating (also known as the anti-knock index) doesn't change the energy content of a gallon of gasoline. A higher octane rating indicates greater resistance to knock, the early combustion of the fuel-air mixture that causes cylinder pressure to spike. When higher-octane fuel is flowing through its injectors, the engine controller can take advantage of the elevated knock threshold and dial in more aggressive timing and higher boost pressures to improve performance” .
 

Junkyard Dog

Well-Known Member
Joined
Jun 3, 2025
Threads
54
Messages
2,560
Reaction score
2,059
Location
Georgia
Vehicle(s)
2024 Dark Horse
The advanced timing and higher boost pressures mean more horsepower.

You are being pedantic. I think you are on the same page with us if you stop to think about it. If you look back, you will also see that nobody, not one post, made the claim that higher octane gasoline makes more horsepower outside of the context of situations that need more octane, such as getting the maximum horsepower out of my 500 horsepower Dark Horse.

So there is not really an argument going on here with two sides.
 


robvas

Well-Known Member
Joined
Mar 7, 2024
Threads
26
Messages
2,749
Reaction score
2,727
Location
MI
Vehicle(s)
2011 Mustang
For those that “mached” :) my comment where I said that octane did not create horsepower. Do you know something that Car and Driver doesn’t ? :)

“Raising the octane rating (also known as the anti-knock index) doesn't change the energy content of a gallon of gasoline. A higher octane rating indicates greater resistance to knock, the early combustion of the fuel-air mixture that causes cylinder pressure to spike. When higher-octane fuel is flowing through its injectors, the engine controller can take advantage of the elevated knock threshold and dial in more aggressive timing and higher boost pressures to improve performance” .
Re-read the last sentence of that quote. And look at this graph to see what timing can do to engine hp

S650 Mustang Are we really using 87 fuel? 59bc3e1a7f7eff25adb2773e2e0b480fe39b48d9.png
 
Last edited:

Junkyard Dog

Well-Known Member
Joined
Jun 3, 2025
Threads
54
Messages
2,560
Reaction score
2,059
Location
Georgia
Vehicle(s)
2024 Dark Horse
Re-read the last sentence of that quote. And look at this graph to see what timing can do to engine hp

59bc3e1a7f7eff25adb2773e2e0b480fe39b48d9.png.webp

Exactly.

And I bet Racer57 agrees.

On the other hand, if I put 93 octane in my 8:1 compression 350 small block from 1974, I am not going to get any more horsepower, so Racer57 is also correct that octane, all by itself, does not add horsepower.

I am just saying no need to fight about it, because we all actually agree.

In the context of the most recent Coyote engine, and the Ecoboost, and all of the other Mustang engines of the current generation, higher octane does add horsepower, because the engines can take advantage of it.

I still have a hard time believing that my 12:1 500 horsepower engine could live a good long life being driven hard in the hot summer in Georgia utilizing 87 octane for a 100,000 mile life. That strikes me as incredible. I also know that Ford engineers have put a lot of study into this that I have not, and a few years ago I would have laughed at the suggestion that one could boost a 12:1 engine and run 93 octane without destroying it in short order, so, well, what do I know?

Maybe I am stuck in the past, but I am going to keep running 93, and I will never let 87 octane pass through the filler neck.
 

Manual Ronnie

Well-Known Member
Joined
Jul 14, 2025
Threads
2
Messages
69
Reaction score
69
Location
Atlanta, GA
Vehicle(s)
‘25 5.0, ‘19 Canyon 4X4, ‘11 Harley Dyna
Using 87 is absurd in something with 12:1 compression ratio. Technically the system can retard timing to allow 87 but should be an absolute special exception
 
  • Like
Reactions: Aki

LouG

Well-Known Member
Joined
Mar 11, 2025
Threads
33
Messages
2,581
Reaction score
2,974
Location
New Zealand
Vehicle(s)
2025 Mustang GT
I'm still a bit surprised at street engines running 12:1 or more. But I do come from the days of 9:1 being high comp.
 

Junkyard Dog

Well-Known Member
Joined
Jun 3, 2025
Threads
54
Messages
2,560
Reaction score
2,059
Location
Georgia
Vehicle(s)
2024 Dark Horse
I'm still a bit surprised at street engines running 12:1 or more. But I do come from the days of 9:1 being high comp.
I pounded the rod bearings out of a 10.5 to 1 engine. But it had cast iron heads and tuning was a carb and a distributor . . . and I sure thought that car was fast until I damaged the bearings, and it was, compared to cars back then.

Cars are much better and more powerful today.

I mean, really, 500 horsepower from a little 307 cubic inch engine? Unimaginable back in the 60s, 70s, 80s, 90s . . . 2000s . . . lol
 

Racer57

Member
Joined
May 14, 2026
Threads
2
Messages
15
Reaction score
43
Location
Illinois
Vehicle(s)
2025 Shelby Cobra
I own a 1970 Plymouth Cuda with 383cu with a 750 dual feed double pumper that I built. Never been on a dyno, but it’s strong. I often refer to the Cuda as having “real” horsepower and my previous Vette and Mach 1 and now Shelby as having “computer” horsepower. :). BTW, you can easily actually see the engine !

S650 Mustang Are we really using 87 fuel? IMG_4267
 

Junkyard Dog

Well-Known Member
Joined
Jun 3, 2025
Threads
54
Messages
2,560
Reaction score
2,059
Location
Georgia
Vehicle(s)
2024 Dark Horse
I own a 1970 Plymouth Cuda with 383cu with a 750 dual feed double pumper that I built. Never been on a dyno, but it’s strong. I often refer to the Cuda as having “real” horsepower and my previous Vette and Mach 1 and now Shelby as having “computer” horsepower. :). BTW, you can easily actually see the engine !

IMG_4267.webp

Nice.

1971 is my favorite year, due to the front grill, but I certainly wouldn't kick a 70 out of my garage!

Can we see a pic of the car (not just the engine)? 🙂
 

Sofa King

Well-Known Member
Joined
Jul 14, 2023
Threads
12
Messages
1,622
Reaction score
1,703
Location
In a VAN down by the river
Website
youtu.be
Vehicle(s)
2024 Ecoboost, Vapor Blue, HPP
Using 87 is absurd in something with 12:1 compression ratio. Technically the system can retard timing to allow 87 but should be an absolute special exception
I'm still a bit surprised at street engines running 12:1 or more. But I do come from the days of 9:1 being high comp.
In the old days 10.5:1 compression ratio was about the max I would run on the street.

I'm with you, but Ford does not present it that way in the manual.
No one would buy them if they required premium only...
Sponsored

 
 








Top