Type of fuel used on BS ?

[dejones64]

89 for the first 3500 miles, average about 28mpg. Gonna bump up to 91 and see if it can do better. But, is the increase in fuel cost gonna make it worth a few mpg more? Don't know, not gonna do the math right now. ?

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[VirtualJMills]

89 for the first 3500 miles, average about 28mpg. Gonna bump up to 91 and see if it can do better. But, is the increase in fuel cost gonna make it worth a few mpg more? Don't know, not gonna do the math right now. ?

Energy yield per gram is going to be the same, so unless the engine is retarding timing, richening mixture, or doing other things currently (on a lower octane rated fuel), there will be no change in fuel efficiency.

The two maps are intended for squeezing more power out of the engine under duress, not more energy per gram of fuel.

 

[Mark S.]

A lot of forced induction vehicles (especially when we are talking about modded cars I know that’s not the case here) call for a higher octane to prevent pre detonation.

I think you have confused two different phenomenon. Detonation is the spontaneous, uncontrolled ignition of the fuel/air mixture AFTER the spark plug fires. Pre-ignition is exactly what it sounds like: the fuel/air mixture ignites BEFORE the spark plug fires.

In smoothly running engine, the spark ignites the fuel/air mixture at just the right time, usually 20-30 degrees of crankshaft rotation before the piston reaches the top of it's compression stroke, producing a flame front that presses down on the piston to produce work. Detonation--also called knock--can range from light to heavy. It occurs after the spark plug fires when the increasing heat and pressure from the primary flame front causes the mixture in other areas of the cylinder to spontaneously ignite. This produces one or more secondary flame front(s). The collision of the two (or more) flame fronts causes a pinging or knocking sound, hence the name for the phenomenon. Light detonation occurs all the time; it's actually required for the engine to operate at top performance. The powertrain control module (PCM), the computer which controls all major engine functions, employs a "knock" sensor that trips at the earliest indication of detonation. The PCM then retards the ignition timing so that the spark fires a bit later. This reduces pressure and heat in the cylinder, which eliminates the knock. The PCM keeps track of detonation events and continually rewrites the the ignition and fuel injection data it stores to control the engine. By keeping ignition timing at the earliest possible without causing detonation the engine is producing the maximum power without endangering the engine.

So how does octane figure in? A fuel's octane rating is an indication of its resistance to knock. Lower octane fuels ignite with lower pressure and heat, so the PCM must retard timing to prevent detonation. The side effect of retarding timing is a power reduction. Higher octane fuels require higher pressure/heat to ignite, so the PCM does not have to retard timing as much. That means more power. What's the power difference between regular and premium gas? It depends, on ambient temperature, altitude, residual engine heat, etc. All things being equal, a ballpark figure of 10-15% is about right. Ford advertises 245 HP for the 2.0L engine, but that's with premium. If you use regular the figure is more like 215-225 HP.

The upshot is if you don't need the extra power use regular gas. The engine is designed to use it and it will cause no problems whatsoever. When you need the extra power, say for towing, fill the tank with premium and the PCM will rewrite the data to take advantage of it and provide more power.

What about pre-ignition? Pre-ignition is bad, period. It occurs when residual heat from the previous combustion event causes the fuel/air mixture to ignite BEFORE the spark fires, while the piston is still traveling upward on its compressions stroke. That means the pressure from the burning mixture is pushing down on the piston against the momentum of the turning engine. This can--and usually does--result in a catastrophic failure of the engine. Heavy detonation can generate enough heat to lead to pre-ignition, which is why the PCM carefully controls ignition to avoid it.

This video provides a good visual to explain the difference between these two phenomenon. (Turn down the sound; the dramatic music is a bit annoying.)




The sharp-eyed among you may have noticed that even when the engine is operating normally ignition occurs while the piston is still traveling upward on its compression stroke. That's correct; normal ignition occurs slightly BEFORE the piston reaches the top of its travel. That's because the mixture burns, it doesn't explode as some think. As it burns the pressure builds then subsides. To get the most work from the engine the maximum pressure from the burn must occur after the piston has reached the top and started traveling downward, but not too long after. Think of it like riding a bicycle: You press downward on the pedal just after it comes over the top. If you press too early then one foot is working against the other. If you wait too long then you only get a portion of the pedal stroke to apply pressure.

It turns out the best time to ignite the mixture to get the most pressure on the piston at the right time is slightly before the piston reaches the top of its stroke. Simple, eh?

 

[fourthgear]

So the engines management system is self learning & can tell which octane rating you are filling the tank with from one tank to the other ?

 

[Mark S.]

So the engines management system is self learning & can tell which octane rating you are filling the tank with from one tank to the other ?

Yes, the PCM is a "learning" computer. It doesn't know what you are putting in the tank per se, but it will adjust to fuel octane on the fly--to a point. I say to a point because if you use fuel with an octane below the minimum recommended detonation can ramp up in severity too rapidly for the PCM to compensate.

Ford recommends a minimum octane of 87 for these vehicles, so nothing lower. That's important, because some fuel stations, especially in mountainous areas, sell "regular" gas with an octane of 85. DO NOT USE 85 OCTANE FUEL IN YOUR BRONCO! You can use 85 octane in a car without a turbocharger at altitude because the thin air limits the amount of power the engine can produce. That's not the case with a turbocharged car. The turbocharger forces air into the engine under pressure, so the engine can still produce maximum or near-maximum power at altitude.

Stick with 87 octane minimum and you'll be golden.

 

[Idontknow]

I think you have confused two different phenomenon. Detonation is the spontaneous, uncontrolled ignition of the fuel/air mixture AFTER the spark plug fires. Pre-ignition is exactly what it sounds like: the fuel/air mixture ignites BEFORE the spark plug fires.

In smoothly running engine, the spark ignites the fuel/air mixture at just the right time--usually 20-30 degrees before the piston reaches the top of it's motion--producing a flame front that presses down on the piston to produce work. Detonation--also called knock--can range from light to heavy. It occurs after the spark plug fires when the increasing heat and pressure from the primary flame front causes the mixture in other areas of the cylinder to spontaneously ignite. This produces a secondary flame front. The collision of the two (or more) flame fronts causes a pinging or knocking sound, hence the name for the phenomenon. Light detonation occurs all the time; it's actually required for the engine to operate at top performance. The powertrain control module (PCM), the computer which controls all major engine functions, employs a "knock" sensor that trips at the earliest indication of detonation. The PCM then retards the ignition timing so that the spark fires a bit later. This reduces pressure and heat in the cylinder, which eliminates the knock. The PCM keeps track of detonation events and continually rewrites the the ignition and fuel injection data it stores to control the engine on the fly. By keeping ignition timing at the earliest possible without causing detonation the engine is producing the maximum power without endangering the engine.

So how does octane figure in? A fuel's octane rating is an indication of its resistance to knock. Lower octane fuels ignite with lower pressure and heat, so the PCM must retard timing to prevent detonation. The side effect of retarding timing is a power reduction. Higher octane fuels require higher pressure/heat to ignite, so the PCM does not have to retard timing as much. That means more power. What's the power difference between regular and premium gas? It depends, on ambient temperature, altitude, residual engine heat, etc. All things being equal, a ballpark figure of 10-15% is about right. Ford advertises 245 HP for the 2.0L engine, but that's with premium. If you use regular the figure is more like 215-225 HP.

The upshot is if you don't need the extra power use regular gas. The engine is designed to use it and it will cause no problems whatsoever. When you need the extra power, say for towing, fill the tank with premium and the PCM will rewrite the data to take advantage of it and provide more power.

What about pre-ignition? Pre-ignition is bad, period. It occurs when residual heat from the previous combustion event causes the fuel/air mixture to ignite BEFORE the spark fires, while the piston is still traveling upward on its compressions stroke. That means the pressure from the burning mixture is pushing down on the piston against the momentum of the turning engine. This can--and usually does--result in a catastrophic failure of the engine. Heavy detonation can generate enough heat to lead to pre-ignition, which is why the PCM carefully controls ignition to avoid it.

This video provides a good visual to explain the difference between these two phenomenon. (Turn down the sound; the dramatic music is a bit annoying.)




The sharp-eyed among you may have noticed that even when the engine is operating normally ignition occurs while the piston is still traveling upward. That's correct. Normal ignition occurs slightly BEFORE the piston reaches the top of its travel during the compression stroke. That's because the mixture burns, it doesn't explode as some think. As it burns the pressure builds then subsides. To get the most work from the engine the maximum pressure from the burn must occur after the piston has reached the top and started traveling downward, but not too long after. Think of it like riding a bicycle: You press downward on the pedal just after it comes over the top. If you press too early then one foot is working against the other. If you wait too long then you only get a portion of the pedal stroke to apply pressure.

It turns out the best time to ignite the mixture to get the most pressure on the piston at the right time is slightly before the piston reaches the top of its stroke. Simple, eh?

Absolutely correct. I used the wrong term. Pre ignition is what I had meant. Thank you for the correction. And that’s an excellent description.

 

[Idontknow]

Yes, the PCM is a "learning" computer. It doesn't know what you are putting in the tank per se, but it will adjust--to a point--to fuel octane on the fly. The reason I say to a point is because if you use fuel with an octane below the minimum recommended detonation can ramp up in severity too rapidly for the PCM to compensate.

Ford recommends a minimum octane of 87 for these vehicles, so nothing lower. That's important, because some fuel stations, especially in mountainous areas, sell "regular" gas with an octane of 85. DO NOT USE 85 OCTANE FUEL IN YOUR BRONCO! You can use 85 octane in a car without a turbocharger at altitude because the thin air limits the amount of power the engine can produce. That's not the case with a turbocharged car. The turbocharger forces air into the engine under pressure, so the engine can still produce maximum or near-maximum power at altitude.

Stick with 87 octane minimum and you'll be golden.

You also don’t want to use 110 octane if you happen to come across a station with it. You need a high compression motor to take advantage of that. It won’t damage it to my knowledge (correct me if I’m wrong) but you won’t see any performance gains.

 

[Osco]

The only non-ethanol fuel we have around here is 91 octane, so that is what I run in all my vehicles. And the Bronco Sport Owner's Manual states 91 octane will also have better engine performance.

I’ve vetted this out before but I’ll do it again for you.
Pulling a trailer or fully loaded in the mountains, higher octane would be cool. It is just a higher anti knock mixture.
It’s also used to get stated Max HP and Torque numbers, looks good on paper.
To benefit in normal driving from premium you need to be in the top 90 to 95 % of your engines power band.
I don’t ever need to floor my engine and I’m in the lower power 1.5L three banger.
In heavy traffic and or hot weather higher octane will help with engine knock. But in our last super hot summer period I was in some traffic and my 1.5 never knocked, was fine on 87 octane..
Just after 5k miles I ran premium for a month. Had a .5 mpg average increase and felt absolutely no power increase because I don’t drive near max power.

That no where nearly justified the 25 to 35% fuel price increase with premium for a max throttle power increase of less than 5%, that again can only be felt with your foot on the floor and your engine up around 5,000 RPM, or more.
I will never drive my engine that hard.
I found similar results with ethanol free.
Our fuel system is designed to handle 10% ethanol with its slower duration but hotter flame propagation.
Our throttle, fuel, and air intake system is optimized from the factory for the best balance of economy and power.
Under normal conditions 87 is fine and the most cost efficient.

FWIW a K&N air filter is 800 times less restrictive when half dirty than a new stock air filter. BUT,,,,
Your air meter/air-gate and throttle control system will simply dial back the air flow to match stock ratios as seen to be best by the fuel control system.
They post the premium fuel used to get the higher power numbers just to remove legal problems….
Burn what ever fuel you like, it’s your money..
PEACE :.P

 

[MaxVelocity]

I’ve vetted this out before but I’ll do it again for you.
Pulling a trailer or fully loaded in the mountains, higher octane would be cool. It is just a higher anti knock mixture.
It’s also used to get stated Max HP and Torque numbers, looks good on paper.
To benefit in normal driving from premium you need to be in the top 90 to 95 % of your engines power band.
I don’t ever need to floor my engine and I’m in the lower power 1.5L three banger.
In heavy traffic and or hot weather higher octane will help with engine knock.
Just after 5k miles I ran premium for a month. Had a .5 mpg average increase and felt absolutely no power increase because I don’t drive near max power.

That no where nearly justified the 25 to 35% fuel price increase with premium for a max throttle power increase of less than 5%, that again can only be felt with your foot on the floor and your engine up around 5,000 RPM, or more.
I will never drive my engine that hard.
I found similar results with ethanol free.
Our fuel system is designed to handle 10% ethanol with its slower duration but hotter flame propagation.
Our throttle, fuel, and air intake system is optimized from the factory for the best balance of economy and power.
Under normal conditions 87 is fine and the most cost efficient.

FWIW a K&N air filter is 800 times less restrictive when half dirty than a new stock air filter. BUT,,,,
Your air meter/air-gate and throttle control system will simply dial back the air flow to match stock ratios as seen to be best by the fuel control system.
They post the premium fuel used to get the higher power numbers just to remove legal problems….
Burn what ever fuel you like, it’s your money..
PEACE :.P

I run premium because it's the only ethanol free alternative I have. I also have documented about a 10% decrease in fuel economy using ethanol laden fuel. So the extra cost is offset.

You don't need to vet anything for me. Between the owner's manual and what I've documented, the vetting has already been done. Thanks anyway!

 

[Mark S.]

It won’t damage it to my knowledge (correct me if I’m wrong) but you won’t see any performance gains.

It depends on what they use to get the higher octane rating. AvGas for piston aviation engines is 100 octane, but you wouldn't want to use it in your car because it uses tetraethyl lead to achieve that octane rating. The lead would cause all kinds of problems in your engine. Similarly, some racing fuels achieve their high octane ratings with ethanol. Regular pump gas in most places uses up to 10% ethanol, but some racing fuels can be much higher, which can also be bad for your engine. Your best bet is to stick with pump gas of 87 or higher octane.

And you're right, above 93 octane you will not see any performance gains; the PCM can only advance timing so far. If you advance timing too far it will move maximum pressure from the burning mixture too early in the cycle, which will actually reduce power output.

 

[Mark S.]

I run premium because it's the only ethanol free alternative I have. I also have documented about a 10% decrease in fuel economy using ethanol laden fuel. So the extra cost is offset.

That's interesting. Efficiency (for the purpose of fuel economy) is measured in miles per gallons. The only way to get more miles per gallon is to use less fuel (increase engine efficiency) or to use a fuel with more energy. Gasoline DOES contain more energy than ethanol, but how much?

One way to measure the amount of energy in fuel is using British Thermal Units (BTUs). Ethanol contains fewer BTUs by volume than gasoline, but what's the difference between straight gasoline and a gallon of gas with 10% ethanol blend? A gallon of gasoline contains approximately 114,000 BTUs, while the 10% ethanol blend contains just a bit under 112,000. That's less than 2% difference.

How are you measuring your fuel economy? The in-dash MPG displays on most newer cars are notoriously inaccurate. They're okay for monitoring trends (changes from one tank to the next), but if you want to know what your precise fuel economy is you have to measure by hand. The best way is to track fuel vs miles over a few tanks to account for differences in how full you get the tank during filling.

 

[Mark S.]

That no where nearly justified the 25 to 35% fuel price increase with premium for a max throttle power increase of less than 5%, that again can only be felt with your foot on the floor and your engine up around 5,000 RPM, or more.
I will never drive my engine that hard.

Under normal driving conditions I agree wholeheartedly with this. If I were towing up a steep mountain, however, I would use premium. Not for the additional power, but for the additional margin of safety higher octane affords in protecting the engine from detonation. Heat is the number one enemy of small-displacement, turbocharged engines, and towing up a steep grade will produce prodigious amounts of it. Higher octane fuel will help avoid some of the most deleterious effects of that heat.

 

[MaxVelocity]

That's interesting. Efficiency (for the purpose of fuel economy) is measured in miles per gallons. The only way to get more miles per gallon is to use less fuel (increase engine efficiency) or to use a fuel with more energy. Gasoline DOES contain more energy than ethanol, but how much?

One way to measure the amount of energy in fuel is using British Thermal Units (BTUs). Ethanol contains fewer BTUs by volume than gasoline, but what's the difference between straight gasoline and a gallon of gas with 10% ethanol blend? A gallon of gasoline contains approximately 114,000 BTUs, while the 10% ethanol blend contains just a bit under 112,000. That's less than 2% difference.

How are you measuring your fuel economy? The in-dash MPG displays on most newer cars are notoriously inaccurate. They're okay for monitoring trends (changes from one tank to the next), but if you want to know what your precise fuel economy is you have to measure by hand. The best way is to track fuel vs miles over a few tanks to account for differences in how full you get the tank during filling.

I track every fill by hand. This has been my experience with my '06 V-10 and '12 Focus 2.0L. It will be interesting to see the results with the '22 Sport.

 

[VirtualJMills]

How are you measuring your fuel economy? The in-dash MPG displays on most newer cars are notoriously inaccurate. They're okay for monitoring trends (changes from one tank to the next), but if you want to know what your precise fuel economy is you have to measure by hand. The best way is to track fuel vs miles over a few tanks to account for differences in how full you get the tank during filling.

Reports so far suggest the in-dash trip A / trip B analytics are pretty accurate within the range of significant figures displayed.

Also, you could monitor actual g/s delivery through the injectors, but then you need to account for the temperature of the fuel, etc… by hand.

 

[Osco]

You said Heat is the number one enemy of small-displacement, turbocharged engines, and towing up a steep grade will produce prodigious amounts of it. Higher octane fuel will help avoid some of the most deleterious effects of that heat.

How does it do this ? Do tell ?
10% ethanol is known to burn hotter but a little slower ?
If your speaking of carbon build up I thought that was no longer an issue In small turbo power plants?
Preventing early detonation ?
Izzat what you mean ?

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