Tested 87, 91 & 93 Octane.

[Idahomaverick60]

That's the Atkinson in the Hybrid.
The air/fuel pushed back gets used for the next cycle so it isn't wasted.

Since the intake valve stays open for part of the compression stroke, the effective compression measured will be less that the typical expectation on an engine with a ~ 13.5 to 1 ratio, but the compression check itself would be the same, although the expected pressure reading will be lower than it would be for a typical 13 to 1 engine.

That's also why it can use 87 without pre-ignition detonation as a "normal" (Otto cycle) with a 13 to 1 would show a strong dislike for that fuel.

As was just noted, while the "effective" compression stroke on the Atkinson is shorter because the intake is open, that means the combustion/power stroke is effectively longer.

The original Atkinson's used a more complicated mechanism to enable the shorter compression/longer power stroke, but the more recent versions get the same benefit with valve control, and by leaving the intake values open the same benefit with less complexity.

We always talk about compression ratio, and it matters, but expansion ratio is what is getting the work out of the combustion. On a traditional engine the compression ratio and expansion ratio happen to be equal. The primary reason to bleed off compression pressure is strictly to humor the EPA. Internal combustion engines areHEAT engines. The hotter they operate (within design parameters) the mor efficient they are.BUT the powers that be have determined NOx emissions are bad. They are made by hight temperature/pressure. So now we reduce effective compression and force exhaust gas in to the engine to make it burn colder.

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[MaverickDragon]

The primary reason for the design of the Atkinson cycle engine was efficiency, and that was the reason for it's development, long before there was an EPA.
The Atkinson cycle engine is more energy efficient, but it produces less power compared with an Otto cycle powerplant, which is why it is typically paired with an electric motor.

This link had a pretty good comparison description.

 

[Tbone91]

I have never run anything lower than 93 premium on my 2017 f150 3.5 Ecoboost since new.

Everyone of my friends drove it was impressed how responsive the truck is.

Truck is 100% stock no tune, no upgrades.

Gotta pay to play. No free lunch

I'm currently running Sunoco 94 octane and while I don't notice the difference from the Sunoco 93 octane it makes me feel like I have to drive it harder also just detailed it yesterday and put my Maverick Truck Club decal on

 

[Cancunbadlands]

91 octane
Every single filled out

 

[HeyBales]

The Motor Trend when the Maverick won 2026 Truck of the Year they have the 2025 Hybrid Maverick Engine Compression Ratio at 13.0:1

Yep - that's the published untrue spec based on math, not usage, they've always put out.
I guess make the engine sound better to those that don't know operation but know engine spec's and what sounds good?

Do people still look thru quick-compare charts with spec's for that to even be noticed now?

 

[MaverickDragon]

Yep - that's the published untrue spec based on math, not usage, they've always put out.
I guess make the engine sound better to those that don't know operation but know engine spec's and what sounds good?
Do people still look thru quick-compare charts with spec's for that to even be noticed now?

You're right, and the spec is actually true, because the standard ratio is calculated by cylinder volume with the piston at BDC vs. TDC...
In the case of the Mav hybrid, with variable valve timing, the actual ratio less the volume while the intake valves remain open isn't likely to be a single number, instead a range of values depending on what the ECU decides is an ideal fuel charge based on the engine load.
Stating that where a number is expected could be confusing.

Is it intended to make it "sound better"?
This might be a good question for the Ford marketing team.

While they may know, in the interim I think it likely they prefer to use the standard calculation rather than a several paragraph explanation of the potential value range.
Maybe they could use an asterisk instead. *

As far as spec comparison, some do. I do.

* Due to the design differences in the Atkinson cycle engine used in the Ford Maverick Hybrid, compared to more commonly used gasoline powered powerplants, the actual compression ratio of the hybrid's engine while in use will have a compression ratio which varies, but will be less than the stated compression ratio figure which is derived using the standard volumetric calculation.

Or maybe not.

P.S. Yes, I enjoyed writing that.

 

[notaz3]

If you used 91 instead of 87 over all those miles on your F150 - you would have spent an additional $3,500 or so. What would that have gotten you?

1) Your engine today would get about 10% more horsepower.

2) Would be getting slightly better mpg’s.

3) Your engine would be cleaner & healthier.

Is it worth it? If money is no object - 91 is a no brainer for 1) & 3). But money is an object and can be spent in many ways. I’m old & frugal with a son like you. Running 91 in my EB is one of my few guilty pleasures

Premium is $0.30 more a gallon over regular at Costco. $0.50-60 more at other stations.

1) Never have I noticed a drop in performance

2) My MPG has remained constant with weather and towing. Yes, I keep track of it

3) Cleanliness comes from the quality of fuel not the pressure at which a fuel spontaneously combusts.

It's not about being "worth it". I simply see no need to spend extra on something unnecessary. The great thing about choice is people are free to chose what they want. I chose to spend my money elsewhere.

 

[Glen Baker LLC]

I've read Costco is top-tier gas.

Costco gas is officially certified as TOP TIER™ Gasoline. Both their regular unleaded and premium grades exceed the EPA's detergent requirements by five times, which helps minimize engine deposits and maintain optimal vehicle performance.

Sadly Sam's club is not.

 

[Chops]

Premium is $0.30 more a gallon over regular at Costco. $0.50-60 more at other stations.

1) Never have I noticed a drop in performance

2) My MPG has remained constant with weather and towing. Yes, I keep track of it

3) Cleanliness comes from the quality of fuel not the pressure at which a fuel spontaneously combusts.

It's not about being "worth it". I simply see no need to spend extra on something unnecessary. The great thing about choice is people are free to chose what they want. I chose to spend my money elsewhere.

I would use 87 if I had a hybrid - 91 not worth the added expense. Defeats the purpose of having a hybrid I think. I would use Top Tier like you do though.

 

[samspritzer]

I've read Costco is top-tier gas.

Costco gas is officially certified as TOP TIER™ Gasoline. Both their regular unleaded and premium grades exceed the EPA's detergent requirements by five times, which helps minimize engine deposits and maintain optimal vehicle performance.

Sadly Sam's club is not.

I wonder about this top tier stuff as I rarely see the sticker on the pump even for those brands that are advertised as such. Plus, the additive is added at the terminal...or is it? Other than an scientific analysis, how else can we tell....

 

[Bob zimmerman]

I wonder about this top tier stuff as I rarely see the sticker on the pump even for those brands that are advertised as such. Plus, the additive is added at the terminal...or is it? Other than an scientific analysis, how else can we tell....

There has been a lot of discussion and validation that ‘Top Tier’ gas does in fact keep injectors clean vs. non Top Tier gas.

For our engines, it does make a difference and I do in fact try to only buy Top Tier gas when i can. Usually a gas station has some pride in their Top Tier gas and will market it as such at the pump.

Bob

 

[kevinmccune]

I could only find the published spec's when I looked couple years ago - which is based on calculation of bore and stroke.
Not the fact a valve is open partway on compression meaning no compression.
Which I found very strange.

atkinson cycle engines use an entirely( sorta) different power stroke long on the power stroke .short on compression if my memory is correct they utilize rather high compression( could be wrong-Toyta claims upwards of 40% efficiency.

 

[kevinmccune]

I wonder about this top tier stuff as I rarely see the sticker on the pump even for those brands that are advertised as such. Plus, the additive is added at the terminal...or is it? Other than an scientific analysis, how else can we tell....

its the same gas basically with a additive package dumped into the tanker upon filling.

 

[kevinmccune]

We always talk about compression ratio, and it matters, but expansion ratio is what is getting the work out of the combustion. On a traditional engine the compression ratio and expansion ratio happen to be equal. The primary reason to bleed off compression pressure is strictly to humor the EPA. Internal combustion engines areHEAT engines. The hotter they operate (within design parameters) the mor efficient they are.BUT the powers that be have determined NOx emissions are bad. They are made by hight temperature/pressure. So now we reduce effective compression and force exhaust gas in to the engine to make it burn colder.

that's why we have the ridiculous diesel urea injection.

 

[samspritzer]

its the same gas basically with a additive package dumped into the tanker upon filling.

My question is more about whether they actually add the additive to the tanker. While the local authorities test the pumps for accuracy, they don't for additives.

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