87 vs 93 Octane

[Yves]

My truck has more than enough power with 87 and I don't tow much with. Why pay more.

Sponsored

 

[fordtruckman2003]

I saw this thread was still going and was just going to come here to post that same gif.

 

[Gros Ventre]

Direct from the owner's manual:

"For best overall vehicle and engine performance, premium fuel with an octane rating of 91 or higher is recommended. "

91 or higher for best overall performance.

Yet the specification remains: 87....

 

[Gros Ventre]

All gasoline, regardless of octane rating, has about 124,000 BTUs/gallon. So the power out of the engine is dependent on the engine design and the octane rating it wants to determine crankshaft developed power. Until we know the design point of the engine everything else is anecdotal... even dynamometer is anecdotal since without setting up the same conditions Ford used, tires, wheel size, engine, transfer case, transmission & axle lube ratings you can't match their setup.

If the spec wasn't good enough, it wouldn't be the spec. ...And the spec remains 87. Using higher octane gives you more margin if you're pushing the engine close to limits.

 

[KingDavid]

Yet the specification remains: 87....

Seems like that's the floor for it to be operational; not the standard for best performance.

 

[Gros Ventre]

Seems like that's the floor for it to be operational; not the standard for best performance.

Operational is operational, until someone can show me the design point of the engine, whether more power is produced with higher octane or not remains to be seen. Like I said above everything else is anecdotal...

 

[Snakebitten]

3.5 Ecoboost on 93 is faster 0-60mph than on 87.

No matter what Otto says.

 

[SilverPigeon]

I make these points for everyone to be aware of. I'm not replying or quoting anyone.
1. I repeat: the OP posted this in the 5.0 V8 forum, so I will confine myself to that engine.
2. There is a fair quantity of hard, EMPIRICAL evidence out there of improved power and torque dynamometer results. These results are NOT anecdotal (if one does not know the difference between empirical and anecdotal evidence, I suggest consulting a dictionary). These results are comparative, using the same test bed and test subjects and are therefore quite valid. Examples of this evidence have been stated previously by @JExpedition07 .
3. There is hard, empirical evidence of improved track times with this engine using higher octane than 87, usually as 93 vs. E85 comparisons.
4. There is authoritative written evidence from the Ford personnel responsible for increased power and torque for fuel up to E85 (a fuel the engine was DESIGNED to run, being flex-fuel capable). This evidence was quoted for us all by @JExpedition07 .
5. In the light of my previous three points, the only conclusion that can be reached is that the engine was designed for the use of E85 and, for any lesser octane fuel, the engine management system will take measures necessary to avoid detonation, down to the safe limit of 87.

Again, I write to inform you all. If one does not believe the hard evidence and hard facts, I could not care less. The burden of proof is NOT upon those who have presented empirical, repeatable evidence, and quoted authority, but on those who believe things are not this way. THAT is how science works.

Turning to @MillstoneF150 's original question:
You may indeed have received sub-par 93, but there is a more likely scenario: I have previously shown a pi-di map for the 5.0 engine. One can see that because of port injection, there is ALWAYS the risk of detonation which if experienced, the engine management will minimise by various means, resulting in reduced power and torque. As can be seen from the map, the situations that contribute to the leanest amount of fuel in the combustion chamber during the compression stroke (and therefore the most risk of detonation) are all related to mid to high load throughout the rev range.

Did you experience such driving characteristics? I would make the 87 vs. 93 comparison when either:
- towing a big load and going WOT or
- going WOT up a steep hill from a standstill.

Can you run 87? Yes, of course because the manual (and engine designers) say so. Should you? If you can afford 93, run it for the extra insurance against engine destruction that it affords.

 

[fordtruckman2003]

3.5 Ecoboost on 93 is faster 0-60mph than on 87.

No matter what Otto says.

Of course this is a 5.0 thread, but at introduction the 2011 3.5 was the fastest stock pickup truck in the USA when running on 93. As proven by many tests by automotive enthusiasts at the time.

 

[Graygoose2021]

Yet the specification remains: 87....

I don't think that's the debate. But if you were fine with less HP that the truck has the ability to do, why not just get the non-turbo 6 cylinder? I mean, you don't use all the HP, why not save money and not buy a V8 or a Powerboost?

 

[Gros Ventre]

I don't think that's the debate. But if you were fine with less HP that the truck has the ability to do, why not just get the non-turbo 6 cylinder? I mean, you don't use all the HP, why not save money and not buy a V8 or a Powerboost?

It has the power I want when I want it... This thing is a rocketship... The key point is whether the additional octane can add power or not. The thermodynamics is clear: octane higher than designed for is wasting money.

 

[Graygoose2021]

True, IF your running 100 octane, your wasting money. Paying for 91 isn't much more than a soda at fill-up. And that's not "over octaing" it. Why not have cleaner power (aka no detonation) when driving, especially during summer months when detonation is more prevalent.
I know 87 will get you around town and down to the bingo parlor...but if you need all the power the truck is capiable of, why not.

 

[Gros Ventre]

True, IF your running 100 octane, your wasting money. Paying for 91 isn't much more than a soda at fill-up. And that's not "over octaing" it. Why not have cleaner power (aka no detonation) when driving, especially during summer months when detonation is more prevalent.
I know 87 will get you around town and down to the bingo parlor...but if you need all the power the truck is capiable of, why not.

Well, so far 87 has given me all the power I need. For example when I punch it on an Interstate or when I tow going over South Pass in Wyoming. The issue is simply "what octane is needed with a 20 psi boost and a 10.5:1 compression ratio." Answer that and you'll know. No on seems to have any idea. Remember every gallon of gas has the same energy content regardless of octane. So the diffference is in the cycle releasing it.

 

[Graygoose2021]

well if its enough power for you, then thats all that matters

 

[JExpedition07]

3.5 Ecoboost on 93 is faster 0-60mph than on 87.

No matter what Otto says.

I’m convinced this is the reason MotorTrend had such slow 0-60 times for their 2021 5.0 test. Everyone else (AutoWeek and Car and Driver got 5.7-5.9 seconds 0-60 for the SCrew 5.0, MT got 6.2 seconds (even slower than the last generation engine with less torque). Made no sense, they either tested at elevation or ran crap gas for the pulls.

Sponsored