Ford Ecoboost Engine

[NateDN10]

Originally Posted By: maersk
A 200 HP naturally aspirated engine will be more fuel efficient than a 200 HP turbocharged engine, when run constantly at 180~200 HP. The turboed engine is more efficient when run at a small fraction of peak power.

Reasons include:

- better cylinder volume to surface ratio promoting less heat loss
- compression ratio, likely lower on the turboed engine
- no energy lost driving a turbocharger (that energy isn't free, it's paid in full in increased backpressure)
- possibly higher rpm range for the same power on the turbo engine (higher air and oil pumping losses, reciprocating mass inertial losses, etc.)

Interesting. I learned something.

So why can turboed gasoline engines be more efficient at lower power outputs? It seems like they have all the same factors working against them then.

 

[maersk]

I think basically because of wider throttle opening for low power operation, reducing pumping losses before they start to run boost, and maybe less reciprocating mass reducing inertial losses at low rpm.

Anyway, the very largest engines in the world (container ship engines and what not) run very low rpms, develop very little power per displacement but are very efficient while the smallest engines run very high rpms, develop a lot of power per displacement but also have very high specific fuel consumption.

Basically, smaller displacement turboed engines are optimised for low power operation compared to a larger displacement, N/A engine, which is more efficient run constantly nearer the full power end of the load spectrum.

 

[unDummy]

Too funny! Ford figured out that they needed an 'oversized' filter! My non-turbo 3.5L 268hp Toyota used 6.4 quarts for its required 5k changes. Does anyone think that the turbo'd Ecosludge engine is UNDER-SUMPED? Like the 1.8t Audi/Passat sludge monster, a bigger oil filter is the solution, but to what problem did Ford already find?

MPG? Power is power. At the same power levels, how much more efficiency can you get from an inefficient design?

Give you a hint, check the 'loaded' engine weights and compare. If you can knock off a few hundred pounds, a 300hp turbo'd lighter vehicle will get better MPG than a 300hp non-turbo'd heavier vehicle.

And, frictional losses when comparing an 8 cylinder engine to a 6-cylinder engine...less pistons, bearings, rods, rockers, cam lobes.... So, it is possible to improve MPG with a turbo. But, 1-mpg improvement isn't something to brag about.

The F150 isn't all that much of a lightweight. Automakers need to put their entire product ranges on slimfast.

 

[UNC017]

Originally Posted By: ammolab
Originally Posted By: NateDN10

Theoretically, a turbocharged engine can recover some of the energy in the exhaust stream to do useful work and thus increase efficiency. In reality, there may be other mitigating factors such as the need to run rich so as not to melt the turbo.


The energy recovered from the exhaust in a turbocharged engine does not drive the wheels...it just crams more fuel and air into the engine. Turbo engines get better mileage because they are smaller displacement Air/Fuel pumps when the vehicle is driven "off boost".


I disagree.

Let's just suffice it to say that although there's a whole spreadsheet's worth of energy gains and losses to be worked through, turbocharging has the NET effect of turning a small percentage of the exhaust heat into torque at the crankshaft. The effect in a diesel engine is HUGE, but its still a few percent in a gas engine.

As for the engine being "a smaller air/fuel pump" when they're off boost... that's true. But its offset by the fact that turbo engines have a very low (inefficient) static compression ratio since they are designed with boost in mind. So let's say you have a 2.2 liter engine in a turbo application, and the same basic 2.2 L engine is used in a non-turbo application. If you ran a test where you compared their efficiency throughout the "zero boost" range of operation, the non-turbo engine would probably win by a significant margin just because of its higher static CR.

 

[UNC017]

Originally Posted By: maersk
A 200 HP naturally aspirated engine will be more fuel efficient than a 200 HP turbocharged engine, when run constantly at 180~200 HP. The turboed engine is more efficient when run at a small fraction of peak power.

Reasons include:

- better cylinder volume to surface ratio promoting less heat loss
- compression ratio, likely lower on the turboed engine
- no energy lost driving a turbocharger (that energy isn't free, it's paid in full in increased backpressure)
- possibly higher rpm range for the same power on the turbo engine (higher air and oil pumping losses, reciprocating mass inertial losses, etc.)


Show me the math, or none of this is true.

 

[Lethal1ty17]

Originally Posted By: 440Magnum
Originally Posted By: maersk
A 200 HP naturally aspirated engine will be more fuel efficient than a 200 HP turbocharged engine, when run constantly at 180~200 HP. The turboed engine is more efficient when run at a small fraction of peak power.

Reasons include:

- better cylinder volume to surface ratio promoting less heat loss
- compression ratio, likely lower on the turboed engine
- no energy lost driving a turbocharger (that energy isn't free, it's paid in full in increased backpressure)
- possibly higher rpm range for the same power on the turbo engine (higher air and oil pumping losses, reciprocating mass inertial losses, etc.)


Show me the math, or none of this is true.



I want to hear this too.

-how much does heat loss really have to do with it realistically?
-the compression ration may be lower in a turbo engine but that is because the cylinder is getting crammed more fully with air with less effort.
-turbochargers use lost energy going out the tailpipe, that is why they increase efficiency, where as superchargers can use up to 25% or more of the power created just to drive the darn thing. power lost from back pressure is so little that it can for all intents and purposes be ignored.
-turbo engines have a higher power density so they can be smaller and still have equivalent power. smaller engine = less reciprocating mass = higher efficiency.

 

[SteveSRT8]

Originally Posted By: NateDN10
Originally Posted By: SteveSRT8
It still takes 300 foot pounds of gas to make 300 foot pounds of torque.

That is silly. First, "foot pounds of gas" doesn't make any sense. Second, efficiency can vary widely. As an extreme example, a rich-running engine will make less power and use more gas than a correctly tuned one.

Theoretically, a turbocharged engine can recover some of the energy in the exhaust stream to do useful work and thus increase efficiency. In reality, there may be other mitigating factors such as the need to run rich so as not to melt the turbo.


Ok you missed a few things here. Number one, power is power. Whether you call it foot pounds or HP, it requires a certain amount of fuel and air to be combusted per unit. Period.

As for running rich, that has little to do with protecting the turbo, it's about protecting pistons!

Might want to do some research. Otherwise you might look "silly".

 

[123Saab]

Originally Posted By: NateDN10

Theoretically, a turbocharged engine can recover some of the energy in the exhaust stream to do useful work and thus increase efficiency. In reality, there may be other mitigating factors such as the need to run rich so as not to melt the turbo.


umm.....melt the turbo?

I have owned several Turbocharged engines, And Never melted a turbo. They are usually either Oil or water cooled, And running the engine rich wont make any difference.

Sure Turbo's fail,But thats usually wear since they do run hot.
And on Oil cooled turbo's that can look like the Engine is running rich, As after a while they will tend to start smoking, and need a rebuild. Usually A long While.....

 

[NateDN10]

Originally Posted By: SteveSRT8
Ok you missed a few things here. Number one, power is power. Whether you call it foot pounds or HP, it requires a certain amount of fuel and air to be combusted per unit. Period.

As for running rich, that has little to do with protecting the turbo, it's about protecting pistons!

Might want to do some research. Otherwise you might look "silly".

I think you missed my point, which was that not all internal combustion engines have the same efficiency.

 

[maersk]

Originally Posted By: 440Magnum
Show me the math, or none of this is true.


Every single one of those points is sound.

Just one example: The volume to surface ratio of the combustion chamber has a direct bearing on the rate of heat loss to the piston, block and head. The more surface area you've got through which to lose a given amount of heat energy, the faster you'll lose it. And that energy is wasted, to be carried off and dissipated by the cooling system instead of doing useful work.

Now, by the law of squares and cubes,

http://en.wikipedia.org/wiki/Square-cube_law

If the combustion chamber is enlarged to twice its size in every direction then its surface area will square but its volume will cube, drastically increasing the volume to surface ratio and reducing the rate of heat loss to the engine.

Now, as to how much each one of those factors I mentioned matters to the whole and how they each scale up or down (reciprocating mass inertial losses, for example, square with the doubling of rpm), yes. You'll have to ask an engineer.

But the fact is:

A 10.85 cubic centimetre 2 stroke engine outputs 1.7 HP @ 16000 rpm (156.68 HP / litre of displacement) :

http://www.osengines.com/engines/la.html

And a 14 x 1,820,000 cc = 25,480,000 cc 2 stroke turbocharged (also supercharged?) engine outputs 108,920 hp @ 102 rpm (4.27 HP / litre of displacement) :

http://www.gizmag.com/go/3263

Now, the ship engine has a best BSFC of 0.278 lbs/hp/hr while the toyplane engine has a BSFC of about 3.529 lbs/hp/hr at full throttle (probably most efficient too?).

You tell me what is true and what not and why.

 

[greenjp]

Magnum, Lethality, you do not want to go down this road, trust me

There couldn't be a more apples to oranges comparison than that of a 2 stroke model plane engine to a marine slow speed diesel. Different applications, different fuels, different everything.

Discussing the SFC of automotive engines at near peak power is also somewhat pointless considering how little time they actually spend at that output level. I'd bet the design operating profiles include less than 5% operating time at peak hp.

jeff

 

[hemitruck]

congrats on your new truck. i can't discuss all the charts and math concerning mpg intelligently, but as the computer learns your driving style and the drivetrain breaks in your mpg will increase some. as the torque is designed to be available at low end, your around town mpg most likely will not improve much. long hwy trips at around 70 mph, not towing i think you'll see 20 or better mpg. what ford did with these engines, is incorporate diesel technology into a gasoline engine. i believe they beefed up the pistons and other parts to increase longevity. hope you will keep us informed as to how your truck holds up and things you find you like and don't like about it.

 

[OVERKILL]

Those are interesting examples, but they don't tell the entire picture.

Honda's S2000 engine for example (to use 4-stroke engines):
237HP out of a 2.0L (122ci) DOHC 4-cylinder. 1.94HP/ci, 118HP/L

A Jon Kaase BOSS-9 Ford:
2,200HP out of a 13.34L (814ci) pushrod HEMI. 2.70HP/ci, 164.92HP/L

Both of these are naturally aspirated, gasoline powered engines. Now the Kaase mill is obviously max effort, I assume the S2000 may have more in it. But to equal the Kaase mill in output, it would have to make an additional 92.84HP; a total of 329.84HP.

**************************

That being said, you just compared a nitro-powered RC engine to a giant Diesel. They don't use the same fuel. That throws a huge wrench into things right there.

A Nitro-powered top-Fuel dragster makes somewhere north of 8000HP from an 8.19L (500ci) engine. That is 976HP/L.

 

[A_Harman]

This is an interesting discussion, but pointless.

Nobody involved has the data at hand, or has the means to produce the data necessary to prove their points. All we can do is talk in generalities about the directional effect of different characteristics. An engine is a complex thermomechanical system that has many design variables that can be tailored to make it useful for a given application.

If I need an engine to power a model airplane, I won't go buy a 109,000hp ship engine.

If I need an engine to power a ship, I won't go buy 64,070 model airplane engines.

Some of the reasons why the ship engine is more efficient than the model airplane engine:
It's a diesel, with much higher compression ratio.
Since it's a diesel, it runs lean all the time, and the average in-cylinder temperatures are lower, meaning less heat loss to the cooling system.
It runs at 1667 ft/min piston speed vs. 2466 ft/min for the OS. Since engine friction losses increase with the square of the piston speed, the OS engine will have 2.19 times the friction loss just from this alone.
The Sulzer engine is a crosshead piston design, which decreases friction even more by eliminating piston thrust loads.
The OS engine is carbureted, and flushes a lot of fuel out the exhaust without ever burning it. The Sulzer does not inject fuel until after the ports are closed, so does not lose much out the exhaust.
Because the Sulzer runs at 102 rpm, and the OS at 16,000, it has 15,700% more time to burn its fuel before the exhaust ports open compared to the OS.
The Sulzer is turbocharged, which in a ship application means that it is always recovering energy from the exhaust and producing positive intake manifold pressure that is required for optimum performance. Ironically, this means that the Sulzer is a downsized engine, compared to NA diesels that would need to be much larger displacement to make the same power.
I'm sure there are many other reasons for the difference in engine performance, but my fingers are getting tired.

 

[maersk]

Originally Posted By: greenjp
Magnum, Lethality, you do not want to go down this road, trust me

There couldn't be a more apples to oranges comparison than that of a 2 stroke model plane engine to a marine slow speed diesel. Different applications, different fuels, different everything.

Discussing the SFC of automotive engines at near peak power is also somewhat pointless considering how little time they actually spend at that output level. I'd bet the design operating profiles include less than 5% operating time at peak hp.

jeff


You might have stopped to consider what I was actually trying to show with this comparison instead of all the things I wasn't as well as the post I was responding to.

One of the things I was trying to show was that engine fuel efficiency correlates, in a general sense, with engine displacement and possibly inversely with rpm range. At least RPM range certainly correlates inversely with engine displacement in a general way.

As for the full throttle SFC measurement, as I am sure you know, Gasoline engines are most efficient at full throttle and fuel consumption figures are quite sparse for such little, specialty engines anyways.

That's the best I could find on their own site and considering that the difference in specific fuel consumption between it and the ship diesel an order of magnitude wide, I doubt it's of any relevance whether fuel consumption was measured at idle, low load or full throttle.

 

[A_Harman]

When comparing bsfc of engines, you need to consider engines burning the same type of fuel. Overkill made a very good point when he pointed out that the model aircraft engine runs on nitromethane. Straight nitro only has about 1/4 the heat content of diesel fuel. Depending on the nitro content of the fuel used, this goes a long way toward accounting for the difference in bsfc between the ship engine and the model airplane engine.

It is very relevant if the fuel consumption is measured at idle, low load, or full throttle. It is a mathematical certainty that bsfc for any engine at idle is infinity. It is burning fuel yet not producing useful work at the flywheel. The numbers quoted were most likely at rated power.

 

[UNC017]

Originally Posted By: maersk
Originally Posted By: 440Magnum
Show me the math, or none of this is true.


Every single one of those points is sound.


Not entirely

Originally Posted By: maersk

Just one example: The volume to surface ratio of the combustion chamber has a direct bearing on the rate of heat loss to the piston, block and head. The more surface area you've got through which to lose a given amount of heat energy, the faster you'll lose it. And that energy is wasted, to be carried off and dissipated by the cooling system instead of doing useful work.

Now, by the law of squares and cubes,

http://en.wikipedia.org/wiki/Square-cube_law

If the combustion chamber is enlarged to twice its size in every direction then its surface area will square but its volume will cube, drastically increasing the volume to surface ratio and reducing the rate of heat loss to the engine.



All nice and intuitive... but in practice completely wrong. Funny how actual engineering is so often the opposite of intuition. If this argument was the WHOLE STORY, then big-block v8s with bores well over 4 inches would still be the norm in pickup trucks, not 5-liter class overhead cam and Hemi types with small bores and long strokes (a much poorer surface/volume ratio). Combustion dynamics are even more important than simple area calculations, and the bigger the cylinder, particularly in the bore dimension, the harder it becomes to control these dynamics, especially in a spark-ignition engine where the A/F mix is present and fills the chamber prior to ignition. Not so much so in a diesel where the cylinder is filled with compressed air and then fuel is burned at the tip of the injector like a blowtorch.

Originally Posted By: maersk

A 10.85 cubic centimetre 2 stroke engine outputs 1.7 HP @ 16000 rpm (156.68 HP / litre of displacement) :




You want to do the CORRECT comparison? Do what I said. Find a gasoline automobile engine available both in N/A form and turbo form, and then compare them under identical operating conditions. I'd suggest using the Chrysler 2.2, but its about 25 years out of date now. Maybe an Ecotec would be a better example. OR how about the Ecoboost we've been discussing?

The simple fact is that when the turbo is producing boost, it is recovering thermal energy from the exhaust and instead of wasting it, it is using it to compress the fuel/air charge instead of tapping the power needed to compress the charge directly from the crankshaft.

The differences are SMALL, and there are operating environments where N/A will be more efficient- NO ARGUMENT THERE. But in general, the turbo engine (if implemented correctly, and I think the Ecoboost most certainly is!) will have the efficiency edge. Heck, the O/P's numbers prove it- 17+ mpg in combined driving with an F-150 is darned impressive.

 

[Cujet]

Originally Posted By: addyguy

You do have a nice truck, but as a general observation, I think these 'Ecoboost' engines will be a disappointment for fuel mileage as time goes on - Ford has really hyped them to do something I'm not sure they can do.


I own an 09 4x4 5.4L F150 SuperCrew lariat. It gets 14MPG in 50-50 driving and about 16 if I am very, very careful.

I also have a 2011 2wd Ecoboost Supercrew XLT as a company owned work truck. It gets 19 in mixed driving and I now have 21MPG showing on the indicator (for the last week). And, I was hauling dirt!

The Ecoboost truck really responds to a conservative driving style. The 5.4, not so much. Put another way, there is no way to achieve good MPG's with the 5.4, it just can't be done. The Ecoboost, when driven slowly (speed limit, 60 or below) is remarkable.

The bottom line is a 4MPG increase. Plus it's WAY faster than my 5.4L truck.

 

[Cujet]

Oh, and 125cc Honda (CR125 based) shifter kart engines produce around 50HP at the wheels! That, my friends is 400HP per liter.

 

[SteveSRT8]

I would agree that 21 mpg is remarkable! Especially in a full size pickup.

We have some Silverados in our fleet, and one regularly gets 17 mpg in the city, the others more like 15.

And they don't have near the power of the ebooster!