87+ Octane Gas vs. 91+ - HELP

[JediMcMuffin]

91 Is almost 7 bucks a gallon.... 87 is about .50-.70 cents cheaper per gallon here in SoCal, I ran 91 for the first 2k miles and recently switched to 87. After 600 miles, I have not noticed a difference in performance in my 2.7. I'm at 1700 feet and mild weather FWIW. I've ran 91 in all my cars since forever but now I'm just trying to save a couple nickels where I can.

CostCo for gas my fellow SoCal friend! I paid $6.01 for 91 octane in San Marcos yesterday.

I am running the FPP tune on the 2.7L, I've run nothing but 91 since putting it in a year or so ago and only this last month have I run 87. God do I miss that horsepower. At first the power loss is negligible and very slowly it pulls back and before you know you're flooring it thinking go damnit go!

Back to 91 for me, until I truly can't afford it.

Sponsored

 

[Last Ride Bronco]

Unless you’re worried about your 0-60 time, stay with 87 octane. Your wallet will thank you.

 

[JediMcMuffin]

Unless you’re worried about your 0-60 time, stay with 87 octane. Your wallet will thank you.

I agree with this, unless you have the FPP tune. Loosing 15-20 horsepower is a lot different than losing 50-60. Before the tune I ran 87 often. I've spent the last month with 87 and I hate it. Though the transmission shift point changes of the tune still make a wonderful difference.

 

[projectbadlands]

Most of you probably know this... but for those that do not....

Octane.... You should be able to run anything from 87 to 93.... Lower octane (87) will explode under pressure sooner than higher octane (89). The higher the octane the higher the pressure before the gasoline self ignites. You do not want the gasoline self igniting before the engine is ready. That is called pre-detonation or "knock". So higher octane gas can be placed under higher pressure for longer without pre-detonating.

Modern engines sense "knock" and can adjust timing (when the valves open/close/spark etc...) based on whether is senses "knock". This allows the engine to gain higher horsepower and torque from a higher octane gas, while still able to run on lower octane gas just at a reduced output.

DO NOT confuse this with top tier fuel.... Two very different things.

"Top Tier" fuel is a name auto manufactures and gasoline producers came up with in the 90's??? I think. "Top Tier" simply means the gasoline you are purchasing has a given minimum level of cleaners/detergents as additives to the gas. If you have ever torn apart an engine or seen an engine torn apart you will see carbon build up, often on valves. That build up becomes hot spots and interferes with air flow. The cleaners help minimize this build up. Direct injection bypasses the valves so they do not get those cleaners in the gasoline/air flowing over them. This was a real problem in the early 2.7 engines. That is why FORD then changed the 2.7 from direct injection to a combination of direct injection with some port injection. The Port injection is not quite as efficient as direct injection but it gets those cleaners across those valves...

This is why I will always run "Top Tier" gasoline no matter what Octane I use. And yes I like the higher out put so I will run a higher octane.... BUT I will typically try to run the same octane (when ever I can)... Every time I change octane the engine will have to adjust the timing and I might get some "knock" while it is doing that... The computers and the sensors are pretty quick these days though and I probably will never even notice any "knock".

Just my take on gasoline.
I am a simple guy and I think of things in simple terms, I am sure there are people on here that know more about it than I do.

I agree with most except the concept of pressure although its not far off. Octance is resistance to heat. Gasoline does not burn under pressure, it burns by heat generated by spark. Only Diesel fuel burns under pressure as pistons compress the fuel inside the combustion chamber. This is why diesels do not have spark plugs.

With that said, turbochargers do generate pressure which does increase heat but not enough to spark fuel.

The higher the octane, the more resistance to heat.

 

[projectbadlands]

CostCo for gas my fellow SoCal friend! I paid $6.01 for 91 octane in San Marcos yesterday.

I am running the FPP tune on the 2.7L, I've run nothing but 91 since putting it in a year or so ago and only this last month have I run 87. God do I miss that horsepower. At first the power loss is negligible and very slowly it pulls back and before you know you're flooring it thinking go damnit go!

Back to 91 for me, until I truly can't afford it.

I just saw 5.89 at Costco in Woodland Hills today. It was over $6 last week.

 

[Roach011]

FWIW - I run the 93 in Texas. I think the bronco runs smoother, and more efficiently with it. Anecdotal for sure: my bronco runs an average MPG of 18.5+ on 93 vs 17 on 87. I'll keep running the higher octane stuff.

 

[mikeeshim]

In the meantime, the price difference works about to be about $5.50 a fillup more with 93 than 87. I worked out that it's around $265 per year more to use 93 over going with 87 at today's price by me, with my commute and number of fillups (about once a week).

Here in southern Cali, the average difference is 87@ $6.509 and $7.099 for 91.
We don't even get 93.

 

[projectbadlands]

Here in southern Cali, the average difference is 87@ $6.509 and $7.099 for 91.
We don't even get 93.

just filled up my truck with 87 at $5.59 ----- 91 was $5.89 in Socal - Woodland Hills.

we do not get 93 because we are at sea level.

 

[CarmeloS]

Yep and it won't stop til everything is electric haaaa

Coal powered vehicles wont be the future, its most likely hydrogen or still be gas and possibly diesel

in the meantime, I want my 30+hp gain, more with the tune and mods

 

[mikeeshim]

not get 93 because we are at sea level.

Valley prices have always been lower than central LA, but that is a giant gap.
Guess I'll have to fill up everytime I drive through the 101 to Oxnard.

 

[MWILD]

I’ve recently switched to Sheetz 88. While not as fast as 93, it’s almost as smooth and feels much better than 87. Currently $3.29 a gallon.

 

[jzweedyk]

just filled up my truck with 87 at $5.59 ----- 91 was $5.89 in Socal - Woodland Hills.

we do not get 93 because we are at sea level.

Sea level you need higher octane. At altitude you don't, as much. That is why most of the west has only 91. On the coast of Oregon they have 93. In Cali, they charge you extra for less.

 

[Last Ride Bronco]

I just saw 5.89 at Costco in Woodland Hills today. It was over $6 last week.

Wow! Gas is $2.96 here! (87 octane)

 

[7sKnuckledragger]

I haven’t seen 3 bucks a gallon for almost 18 years here. But hey… we have…. Well yeah Cali is great

 

[PolarVortex]

Hi all, I went to the dealership today for my 1000 mile oil change (I know this isn't needed) and requested synthetic blend this time and will switch to fully synthetic on my 5000k oil change later this year. When I was in the service center I asked one of the techs about high octane gas and he recommended I "stay away from those 91+ octane fuels, because they do more damage then good to the 2.3L engines". Can anyone help clarify this for me? I have filled up using 93 octane from Shell (live in MA) since new. I don't want to do damage to anything but also want to do whats best for the engine to make my baby last as long as possible.

Your Bronco is freaking beautiful.

Sponsored