400hp on Platinum only with 91 octane gas?

[Scottorama]

I just didn't realize that advertised HP numbers are all based on 91 octane gas, even though user manuals and "minimum" specs require 87. Lame marketing IMO.



That’s not really how I see it. You shouldn’t have to buy top of the line gasoline to get the advertised HP numbers, when the user manual says 87 (when it’s actually 91). Little truth in advertising would go a long way, such as “400hp (with 91 octane gas)”.

This isn’t some premium European sports sedan. It’s an American truck.

This is like shooting fish in a barrel......you really need to learn how to read a users manual. See the paragraph where it says to use premium with 91 octane or higher. Or better yet read the part about using 87 octane and it causing loss of power and causing engine knock.....

From the Yukon Denali owners manual:

 

[edizzle]

I just didn't realize that advertised HP numbers are all based on 91 octane gas, even though user manuals and "minimum" specs require 87. Lame marketing IMO.



That’s not really how I see it. You shouldn’t have to buy top of the line gasoline to get the advertised HP numbers, when the user manual says 87 (when it’s actually 91). Little truth in advertising would go a long way, such as “400hp (with 91 octane gas)”.

This isn’t some premium European sports sedan. It’s an American truck.

I would agree with your sentiment

 

[Artie]

This was specifically covered on both Ford and Lincoln websites, I clearly remember reading this when building both Expy and Navi in the weeks before I ordered. This isn’t anything new for any auto manufacturer.

 

[Scottorama]

.

 

[Edistobob]

This is like shooting fish in a barrel......you really need to learn how to read a users manual. See the paragraph where it says to use premium with 91 octane or higher. Or better yet read the part about using 87 octane and it causing loss of power and causing engine knock.....

From the Yukon Denali owners manual:

View attachment 24570

And the following is from the 2018 Expedition manual, pages 177 and 178 (2nd printing). It is easy to see why there is confusion:

FUEL QUALITY Choosing the Right Fuel E161513 Your vehicle is designed to operate on regular unleaded gasoline with a minimum pump (R+M)/2 octane rating of 87. Some fuel stations, particularly those in high altitude areas, offer fuels posted as regular unleaded gasoline with an octane rating below 87. For best overall vehicle and engine performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel is most noticeable in hot weather as well as other conditions, for example when towing a trailer. See Towing (page 264). Do not be concerned if the engine sometimes knocks lightly. However, if the engine knocks heavily while using fuel with the recommended octane rating, contact an authorized dealer to prevent any engine damage. We recommend Top Tier detergent gasolines, where available to help minimize engine deposits and maintain optimal vehicle and engine performance. For additional information, refer to www.toptiergas.com. Note: Use of any fuel for which the vehicle was not designed can impair the emission control system, cause loss of vehicle performance, and cause damage to the engine which may not be covered by the vehicle Warranty. Do not use: • Diesel fuel. • Fuels containing kerosene or paraffin. • Fuel containing more than 15% ethanol or E85 fuel. • Fuels containing methanol. • Fuels containing metallic-based additives, including manganese-based compounds. • Fuels containing the octane booster additive, methylcyclopentadienyl manganese tricarbonyl (MMT). • Leaded fuel, using leaded fuel is prohibited by law. The use of fuels with metallic compounds such as methylcyclopentadienyl manganese tricarbonyl (commonly known as MMT), which is a manganese-based fuel additive, will impair engine performance and affect the emission control system

 

[Mike Wolfe]

Why is everyone upset with the fact that these engines produce more hp on premium fuel
Gm & Ford vehicles with the flex fuel option will see a 15-20% increase in HP & Torque if using 108 octane E85 fuel
Wish Ford made a flex fuel version of the eco boost series
Could get some serious HP & Torque from a turbo engine with 108 octane fuel
To bad we are plagued with 87 octane "CRAP" as our base fuel anyway
I am a retired automotive fuel systems engineer
I have always used the highest octane fuel I could obtain in my vehicles & will continue to do so
Of course I always recalibrate my vehicles to optimize engine performance the day after I get them anyway
Typically use Livernois software
Often the improvement in performance results in better fuel mileage
While I have not tried to compare 87 verses 91 in my ecoboost it is likely an improvement in fuel mileage would be realized
Of course if you like to hit the throttle to feel the extra power produced, you may not see any improvement
Have a nice day all

 

[07xln]

The nice thing with GM’s V8 in the Yukon Denali is it hauls with 420hp on 87 octane.

No it doesn’t

One minor thing you’re forgetting. The Denali doesn’t have 2 turbos strapped to the front of it. Boost is a completely different animal and will always benefit from better quality fuel

 

[NyackRob79]

Why is everyone upset with the fact that these engines produce more hp on premium fuel
Gm & Ford vehicles with the flex fuel option will see a 15-20% increase in HP & Torque if using 108 octane E85 fuel
Wish Ford made a flex fuel version of the eco boost series
Could get some serious HP & Torque from a turbo engine with 108 octane fuel
To bad we are plagued with 87 octane "CRAP" as our base fuel anyway
I am a retired automotive fuel systems engineer
I have always used the highest octane fuel I could obtain in my vehicles & will continue to do so
Of course I always recalibrate my vehicles to optimize engine performance the day after I get them anyway
Typically use Livernois software
Often the improvement in performance results in better fuel mileage
While I have not tried to compare 87 verses 91 in my ecoboost it is likely an improvement in fuel mileage would be realized
Of course if you like to hit the throttle to feel the extra power produced, you may not see any improvement
Have a nice day all

I would bet the reason why Platinum puts out 400hp vs other trims’ 375hp is due to an increase in turbo boost. That’s the simplest kind of engine tuning on forced induction engines there is. Higher boost = higher chance of pre-detonation. And since octane is a detonation retardant, this allows you to squeeze more air and gas into the cylinder without it going off prematurely. It’s the reason why all import tuners are turbo. They’re the easiest cars to mod. I would also bet it’s how the Navigator gets 450hp out of the same engine. More turbo boost.

I won’t bother with a dyno (who would?), but maybe next time I fill up on 87 I’ll do a quarter mile run on the highway onramp while unloaded, and then do the same on 91 octane. The 25hp should yied a noticeable difference in time.

 

[proeasy]

The US Automakers have been pushing the Fuel Companies and the Government for a trend towards 95 min octane, that would perhaps give a 3% overall fuel economy improvement. Not a fuel expert but I am sure the gas companies love the margin increase when we select premium

https://www.forbes.com/sites/samabu...emium-gas-to-be-the-new-regular/#167da1306e9d

 

[jeff kushner]

Premium fuels burn slower, providing more complete combustion and the control of it to some extent, by itself, it does nothing more other than possibly containing a better additive pkg...Octane is "resistance to detonation", HOWEVER it allows the software designers to make changes to the advance of the ignition and changes to the valve timing along with control of the intakes, boost's and fuel timing to allow optimum power in the 3.5.


At high cylinder pressures(remember, your compression gauge is only measuring static compression, not what's going on when it's running) often show over 1,100psi at peak pressure during combustion, the slightest imperfection can become a catalyst for unplanned ignition or detonation. Using a fuel that provides more resistance to that absolutely engine-destroying condition, just makes sense to me. Someone earlier nailed the price-point at 15 bucks a tank. I have built too many engines and seen the popcorned and pock-marked surfaces of heads and pistons hundreds of times over and the sheer violence of a pre-ignition event is quite similar to you slamming the top of your piston with a sledgehammer while it's still on the way up!

jeff