My Real World Hybrid MPG

[mamboman777]

FordBossMe (Ford Master Mechanic on YouTube) just posted a video on octane and compression ratios. In the comments, I asked him about this, and according to him, those compression numbers is measured when the valve is fully closed, so He's suggesting a high octane would be appropriate on the Mav Hybrid.

You can use whatever gas you want.

Everything that I can find mentions that compression ratio is calculated by measuring the volume when the piston is at its lowest point and again at the highest point including the area above the block. I find no mention of valves.

I also find that the Atkinson cycle engine used by Ford and Toyota keeps the intake valves open for %20-30 of the compression stroke. That means, if my math is correct, that the functional compression ratio of the engine is between 9.1:1 and 10.4:1.

That said, i completely agree with what he's saying regarding the Ecoboost engine. Makes perfect sense to me.

I disagree with what he's saying regarding the hybrid engine.

That said, if you want to use gas that costs $1 more because of this video on you tube, power to you. You're not spending my money.

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[flashfearless]

I’ve been watching his videos working on these Ford cars for a while. I tend to trust his judgement. I’ll probably try a tank of 91 on my road trip and see if I notice a difference

 

[Darnon]

Everything that I can find mentions that compression ratio is calculated by measuring the volume when the piston is at its lowest point and again at the highest point including the area above the block. I find no mention of valves.

Yeah, measuring a dynamic CR that way would be an absolute nightmare having to take into account variable valve timing or variable compression ratio strategies. Like no one specs CR based on forced induction pressure over ambient.

 

[mamboman777]

Yeah, measuring a dynamic CR that way would be an absolute nightmare having to take into account variable valve timing or variable compression ratio strategies. Like no one specs CR based on forced induction pressure over ambient.

Right, but the point is, it's not 13:1. Also, the reason for needing higher octane is because the compression in the cylinder sometimes causes the fuel to ignite earlier than the spark. However, what I'm saying is the compression in the cylinder doesn't get high enough to cause early ignition because the valves are open during part of the compression stroke.

 

[OakRun]

Audit of Ford Maverick instrument mileage display...
This vehicle is 2022 Maverick Lariat hybrid with lux package delivered in March. I have recorded all the fuel added to the vehicle. Each time I fill the tank I record the mileage displayed on the instrument panel and then zero it before driving on the next tank. Results: 6229.2 miles; actual MPG: 39.73; average of all the mileage displayed on the instrument: 41.66.

 

[GPSMan]

Right, but the point is, it's not 13:1. Also, the reason for needing higher octane is because the compression in the cylinder sometimes causes the fuel to ignite earlier than the spark. However, what I'm saying is the compression in the cylinder doesn't get high enough to cause early ignition because the valves are open during part of the compression stroke.

Correct.

The ACTUAL compression ratio of the Atkinson engine is LOW. This is the whole point. Less pumping losses, greater efficiency.

Lowest octane available (85 in Mountain states) should be used in the hybrids.

 

[Waterick]

I'm still not sure why Ford recommends 91 octane.....

 

[Waterick]

To be clear. I'm talking about the hybrid here.

 

[jsus]

I'm still not sure why Ford recommends 91 octane.....

To be clear. I'm talking about the hybrid here.

Standard text used in all manuals, regardless of the actual difference it makes with any given engine.

 

[GPSMan]

I'm still not sure why Ford recommends 91 octane.....

That applies only to the EcoBoost and then, it's only "needed" at wide open throttle. If you don't drag race, 87 octane is fine. ALL CARS SOLD must be able to run on 87 octane by law, but with less than maximum horsepower output in some cases. This is so any fuel may be used for hurricane evacuation, time of war, or other supply chain disruptions of the more "premium priced" fuels.

 

[Waterick]

Thanks for clearing that up, I was begining to wonder if I really wanted to put premium fuel in a hybrid.

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