Observations on 2000 mile road trip in 2.0 EB

[351cid]

Just completed a 2000 mile road trip from VA to IL to MO to NC and back to VA. 2105 miles. My (wife's) car is a 2013 Fusion SE with 2.0L EB. The car is exactly as it came from Ford except 5W30 Mobile 1 and Toyo tires.

 

Average for the entire trip was 30.1 mpg. This included city driving while at the family reunion in Peoria, IL. Reported are from the car's trip computer which has been verified to be accurate with in .1 mpg (hand calculated). This was on 87 octane fuel as in the past I've tried 93 and saw no real gain in MPG. The vehicle has 3 "good sized" adults and luggage.

 

This is hardly scientific; but here is what I learned.

 

70 mph is the aerodynamic threshhold. Up to 70, the car would maintain 32-33 mpg easily. Interestingly, terrain was not that big of a factor. The fuel mileage in WV wasn't that much different than what I saw in IL.

 

Above 70, the mileage took a significant hit. Best I got with cruise set on 75 mph was 28.2; while worst was 26.9.

 

65 mph cruise, I was able to knock down 35 mpg. That actually came in TN to NC (pretty mountainous area).

 

I am not a "jack rabbit" starter. I don't hyper mile, but I am easy on the throttle.

 

Thought some folks that question Ford's EB technology might be interested in this. I'm sold on the fact that it works. Your mileage may vary.

 

 

[jinx8402]

70 mph is the aerodynamic threshhold. Up to 70, the car would maintain 32-33 mpg easily. Interestingly, terrain was not that big of a factor. The fuel mileage in WV wasn't that much different than what I saw in IL.

 

Above 70, the mileage took a significant hit. Best I got with cruise set on 75 mph was 28.2; while worst was 26.9.

 

65 mph cruise, I was able to knock down 35 mpg. That actually came in TN to NC (pretty mountainous area).

 

This has been my experience on long trips as well. I think the other thing that comes into play is moving the vehicle at those speeds requires more boost. Would be curious to see if the 1.5 or 1.6 would see that point a little lower (68-69 MPH) due to the smaller engine.

[92merc]

Your observations on the 2.0EB match fairly close to my Escape's results. I have more wind resistance, and AWD. But up to about 70mph, my mileage is close to 27. As soon as I kick it up to 75-80, it'll drop to 23. And windy days really affect my mileage being a taller vehicle. If you know anything about ND, it's that we're windy.

[akirby]

That confirms my observation that the mpg curve is not a curve but more of a cliff. Go over the threshold just a tiny bit and mpg suffers dramatically.

[RichardJensen]

I think part of that is gearing, though....

 

I see similar results w/my 2.5L Fusion. There's about a 10% drop off from 70 to 75 (~35 to ~32). Additional OD gears in the new transmissions should bump that up a bit, I would think.

[akirby]

But you're in 6th gear from 50 MPH or so.

[351cid]

If you know anything about ND, it's that we're windy.

I've spent the last 4 years running freight from VA to Calgary during November to March. I am quite aware of the wind. That wind costs me 1.5 mpg average in a big truck...when 7.0 MPG is "good" mileage.

[351cid]

That confirms my observation that the mpg curve is not a curve but more of a cliff. Go over the threshold just a tiny bit and mpg suffers dramatically.

Same results in my V-10 SuperDuty. I average 15 mpg doing 65 or less, but drops to 12mpg at 75. Guess who drives like a Peepaw when trips involve the SD?

[RichardJensen]

But you're in 6th gear from 50 MPH or so.

 

That doesn't mean that the engine is as efficient at, say, ~2400 RPM as it is at ~2100

[Biker16]

That confirms my observation that the mpg curve is not a curve but more of a cliff. Go over the threshold just a tiny bit and mpg suffers dramatically.

 

 

I think part of that is gearing, though....

 

I see similar results w/my 2.5L Fusion. There's about a 10% drop off from 70 to 75 (~35 to ~32). Additional OD gears in the new transmissions should bump that up a bit, I would think.

 

Power[edit]

The power required to overcome the aerodynamic drag is given by:

Note that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.

[351cid]

 

That doesn't mean that the engine is as efficient at, say, ~2400 RPM as it is at ~2100

Something that was learned with the SD....

 

It came with 3.73 gears. I pull a lot with the truck, so I swapped in 4.30 gears. I only lost .5 mpg on the highway even though it turns 500 more rpm. Around town I can't tell if it lost or gained. It did gain 1-2 mpg when towing. Throttle position is a big factor in fuel efficiency.

[Biker16]

 

That doesn't mean that the engine is as efficient at, say, ~2400 RPM as it is at ~2100

 

Ecoboost engines Are different, the fuel consumption curve isn't always tied to RPM.

the ECU is doing alot to keep the Engine from falling apart. then there is that nasty issue of fuel dumping under high loads. overdriving the engine increases the load on the engine, (i.e. more Leverage) this can cause the Engine to use more fuel to maintain combustion temperatures.

[RichardJensen]

75 = 1.0714 * 70

 

Ergo, the power required to overcome the increase in drag increases 1.2299x (delta v ^ 3) from 70 to 75MPH

 

FE does not decrease 23% from 70-75, it decreases--with my car--about 10%.

 

Engine efficiency is not fixed, therefore it must be accounted for in any equation deriving fuel efficiency from velocity.

[akirby]

That's the point - ecoboost engines have to do more with fuel management than NA engines. Running rich to cool the heads e.g. That's not a linear function, thus the "cliff".

[RichardJensen]

 

the fuel consumption curve isn't always tied to RPM.

 

The edge conditions you describe would not normally occur at 75MPH in steady-state cruising.

 

Further, the mileage drop off reported for their EB engines is roughly analogous the the mileage drop off I've observed in a non-EB engine, therefore at least *some* of the effects are probably due to the gear ratios of the 6 speed transmission that (AFAIK) all of us have in common.

[RichardJensen]

That's the point - ecoboost engines have to do more with fuel management than NA engines. Running rich to cool the heads e.g. That's not a linear function, thus the "cliff".

 

I do not believe that at ~2400 RPM (which is where my car runs at 75MPH in 6th), the EB engine is so stressed that it has to run rich to cool the heads.

Edited August 6, 2015 by RichardJensen

[Biker16]

75 = 1.0714 * 70

 

Ergo, the power required to overcome the increase in drag increases 1.2299x (delta v ^ 3) from 70 to 75MPH

 

FE does not decrease 23% from 70-75, it decreases--with my car--about 10%.

 

Engine efficiency is not fixed, therefore it must be accounted for in any equation deriving fuel efficiency from velocity.

 

True, it is possible that as drag increases other sources of Losses decrease. Or that the engine is only 20% thermally efficecnt and increases

 

 

The edge conditions you describe would not normally occur at 75MPH in steady-state cruising.

 

Further, the mileage drop off reported for their EB engines is roughly analogous the the mileage drop off I've observed in a non-EB engine, therefore at least *some* of the effects are probably due to the gear ratios of the 6 speed transmission that (AFAIK) all of us have in common.

 

they could occur if engine temperature or topography (inclines) are encountered. Either way lower RPM could decrease no increase efficiency.

 

 

I do not believe that at ~2400 RPM (which is where my car runs at 75MPH in 6th), the EB engine is so stressed that it has to run rich to cool the heads.

 

I think you misunderstand, if the "edge" conditions were so infrequent why have there been so many complaints about poor fuel economy with ecoboost engines? even in my focus with a GDI engine it can be very temperamental.

 

Also AKIRBY keeps misstating this fact,

 

To be clear it isn't the heads that need cooling it is the combustion chamber, which can become too hot very quickly under load, Especially with heavy EGR use. They can also cool down just as quickly.

[RichardJensen]

People getting into those edge conditions through aggressive throttle use, not steady-state cruising.

[Anthony]

I'm getting 30mpg lifetime on my 2.0 GDI. I consider that very good because it spends about 80% in stop and go traffic. I only wish I had aerodynamics at higher speeds to be concerned about!

[YT90SC]

On the topic of gear ratios: Fuel usage will go UP if the engine is lugging. Timing is pulled to prevent ping and keep power levels up. EGR is reduced. Fuel is added to keep in cylinder temps down. Now add to that mix an OD ratio too tall for a given higher speed and you have to lug and fight wind drag which just makes the problem worse.

[YT90SC]

Ecoboost fuel economy complaints come from feeding it the cheapest gas available compounded by lower NVH than the engines they replaced. If they shared NVH profiles then people would more readily be able to realize that their right foot is in the radiator.

[jpd80]

It actually has less to do with any of that and more to do with the geometric progression of boost in a turbo.

You go from light to moderate boost with very minute movements of the throttle, anyone not driving with

backing out of the throttle constantly is going to use more fuel.

 

Even using cruise control with an Ecoboost engine will ruin your day. Our experience in Australia with

the 2.0 Ecoboost versus the 4.0 I-6 Falcon is that both end up using about the same amount of fuel,

the 2.0 EB may be slightly more fuel efficient in city and highway driving but only if you drive gently.

 

The real find has been the 2.7 V6 diesel in Territory, now that engine does deliver 20% better economy

over the 4.0 I-6 engine. In an AWD Utility that approaches 4300 lbs, that's impressive.

Edited August 7, 2015 by jpd80

[351cid]

 

 

Even using cruise control with an Ecoboost engine will ruin your day.

All of my results were from using the cruise control. I think I have lead in my toes because when I use the throttle, I just steady increase speed.

[old_fairmont_wagon]

Altitude also plays a part in the energy use equation. While the Appalachian mountains are not the Rockies at the continental divide, they are still a non-trivial amount over sea level. When you're maintaining 70 there, your aerodynamic drag calculations are definitely affected by the reduced air density. However, because the air is thinner, more boost is used to maintain the desired cylinder pressures. While this maintains the power output of the engine at elevation, it does consume more fuel. The end result though is largely similar, the faster you go, the more fuel is used and at a non-linear rate.

[ANTAUS]

Hehe...HWY EPA over 20MPG...thats cute.. can't say I've seen that in my long trips....