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Old 11-13-2020, 03:13 PM   #101
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Originally Posted by DavidEM View Post
That is not true. Why do you think Ford's 2.7 liter EcoBoost engine gets such good fuel economy- because they are small displacement and work relatively hard.

Gasoline engines which are throttled are always more efficient if smaller for a given horse power output. Throttling a big gasoline engine is inherently inefficient.

But you do have to consider engine life for a small engine. I doubt that the EcoBoost would last for 200,000 miles while putting out 100 hp continuously. Diesels can do it but they have heavy blocks and a fuel that lubricates to help with wear.

The foregoing makes me wonder why Ford came out with their new 7.3 liter V8 for E350, E450 and F53 chassis. It would seem that a 4-5 liter engine would be more efficient, even at 100 hp, perhaps with a mild turbocharger. Maybe engine life is more important. Nothing beats cubes for engine life.

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With due respect, you missed the meaning of the message on multiple levels.

Motorhomes burn most of their fuel while cruising at highway speeds, not stuck in traffic like many Ford F-150 pickups that are used as daily drivers. My reply was to contradict Bobís comment about having a tiny engine powering a generator or alternator that would then power electric motors. For a motorhome driven mostly on highways, Bobís idea would be VERY inefficient. Thatís why itís not done. If it saved fuel, weíd be doing it already. Itís technically possible, but makes no real sense.

Your comment about the 2.7L EcoBoost is misleading at a technical level in many ways when applied to a motorhome that requires 100 HP or more to maintain speed on highway.

A 2.7L EcoBoost does save a little fuel compared to a 5.0L V8 on the highway when compared on an empty F-150 pickup, but they require a fraction of the power that a 20,000-pound motorhome requires. Many motorhomes need roughly 3 times as much power as a pickup, which is why they only get 8 MPG versus 24 MPG for a pickup at same highway speed.

Engine size makes a difference, but itís the motorhome size and weight that makes it necessary to have a much larger engine to optimize fuel economy. If you make engine too small, it will actually end up getting lower MPG. Thatís why Ford determined that a 7.3L V8 was best for large trucks and motorhomes.

As I stated in other threads, a +/- 5L EcoBoost could have developed the same or more power and torque as a naturally aspirated 7.3L V8, but it would cost more and not get enough added fuel economy to justify the added costs.

Itís a complicated subject, and difficult to discuss in a meaningful way without hijacking this thread.
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Old 11-13-2020, 03:25 PM   #102
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MotorTrend reports the new Transit independent rear suspension is rated at 6,000 pounds, the highest used on a van. That should be enough for the F-150 pickup as well.

I hope this rear suspension finds its way into gas-powered vans which should improve ride quality, particularly for passenger and RV applications.

https://www.motortrend.com/news/2022...t-look-review/
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Old 11-13-2020, 03:36 PM   #103
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With due respect, you missed the meaning of the message on multiple levels.

Motorhomes burn most of their fuel while cruising at highway speeds, not stuck in traffic like many Ford F-150 pickups that are used as daily drivers. My reply was to contradict Bobís comment about having a tiny engine powering a generator or alternator that would then power electric motors. For a motorhome driven mostly on highways, Bobís idea would be VERY inefficient. Thatís why itís not done. If it saved fuel, weíd be doing it already. Itís technically possible, but makes no real sense.

Your comment about the 2.7L EcoBoost is misleading at a technical level in many ways when applied to a motorhome that requires 100 HP or more to maintain speed on highway.

A 2.7L EcoBoost does save a little fuel compared to a 5.0L V8 on the highway when compared on an empty F-150 pickup, but they require a fraction of the power that a 20,000-pound motorhome requires. Many motorhomes need roughly 3 times as much power as a pickup, which is why they only get 8 MPG versus 24 MPG for a pickup at same highway speed.

Engine size makes a difference, but itís the motorhome size and weight that makes it necessary to have a much larger engine to optimize fuel economy. If you make engine too small, it will actually end up getting lower MPG. Thatís why Ford determined that a 7.3L V8 was best for large trucks and motorhomes.

As I stated in other threads, a +/- 5L EcoBoost could have developed the same or more power and torque as a naturally aspirated 7.3L V8, but it would cost more and not get enough added fuel economy to justify the added costs.

Itís a complicated subject, and difficult to discuss in a meaningful way without hijacking this thread.
It is done every day across America: Diesel-electric locomotives are a Diesel engine connected to a generator which connects to electric motors at the drive wheels.
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Old 11-13-2020, 04:02 PM   #104
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It is done every day across America: Diesel-electric locomotives are a Diesel engine connected to a generator which connects to electric motors at the drive wheels.
It's just a matter of scaling it up or down: for the application...
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Old 11-13-2020, 04:09 PM   #105
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It's just a matter of scaling it up or down: for the application...
Sure but I'm also sure that there are reasons that it isn't done on cars/trucks/RVs/etc. but it is done in trains (been done this way in trains for years but no one has done it in anything with tires..why?)
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Old 11-13-2020, 04:13 PM   #106
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It is done every day across America: Diesel-electric locomotives are a Diesel engine connected to a generator which connects to electric motors at the drive wheels.

And you think locomotives have ďtinyĒ engines, or that they were designed that way to improve fuel economy?

Itís too difficult to discuss engineering when the context keeps getting revised to suit an agenda. At least while trying to be helpful in a civil tone.
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Old 11-13-2020, 04:29 PM   #107
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It's just a matter of scaling it up or down: for the application...

Ok, letís expand on this.

Your Smart car weighs about 1/10th as much as a large Class A, yet you donít get 10 times the fuel economy on the highway. Iíd say motorhomes are pretty good by comparison already.

Given the weight difference, would you be willing to scale the engine in your Smart car down to +/- 700 cc and without turbos? With maybe 35 HP?

Iíd bet no, because we canít scale down human expectations. Each application has to be evaluated on its own. By the way, 35 HP works at an old VW Beetle level of performance, but is no longer acceptable.
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Old 11-13-2020, 04:40 PM   #108
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Sure but I'm also sure that there are reasons that it isn't done on cars/trucks/RVs/etc. but it is done in trains (been done this way in trains for years but no one has done it in anything with tires..why?)
The electric drive had or has many advantages for locomotives that donít apply to road vehicles. The main reason was it served as a transmission that could get incredible weight moving at very slow acceleration rates. Mechanical transmissions with gears to do the same would have been impractical by comparison.

It also allows easier way to drive many wheels on a locomotive for added traction. And it made it easy to use multiple locomotives on a single train. Again, of no benefit in a car or motorhome.

Over 50 years ago I doubt fuel economy was that big a concern, particularly since rail was inherently more fuel efficient already.
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Old 11-13-2020, 05:05 PM   #109
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A bit more history on diesel-electric locomotives: The implementation of the idea came from Europe, where they strung electric cables over the rail lines. They didn't need the diesel engines. (And yes, they used electric motors so that they could get very large, very heavy, loads moving with very low acceleration without the need for a transmission.) The purpose was to transition from steam locomotives to electric. The US has much larger open lands that train tracks traverse, much of it without easy access to electric at the time this transition from steam to electric happened, so stringing power lines over the tracks was impractical. We instead built the electric locomotives with diesel generators to get the same benefit without having to run the cables.

None of this had anything to do with efficiency of power generation, except in terms of generating motive force from electric vs. steam.
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Old 11-13-2020, 05:58 PM   #110
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Ok, letís expand on this.

Your Smart car weighs about 1/10th as much as a large Class A, yet you donít get 10 times the fuel economy on the highway. Iíd say motorhomes are pretty good by comparison already.

Given the weight difference, would you be willing to scale the engine in your Smart car down to +/- 700 cc and without turbos? With maybe 35 HP?

Iíd bet no, because we canít scale down human expectations. Each application has to be evaluated on its own. By the way, 35 HP works at an old VW Beetle level of performance, but is no longer acceptable.
I'm much closer than you think...
I'm averaging almost 53 mpg; with a high of almost 72!
Scale it down to 35 horsepower?

https://www.thorforums.com/forums/at...1&d=1605290433
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Old 11-14-2020, 04:01 PM   #111
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Getting back to the electric van, what do you guys think is going on at the rear where the suspension and drive motor should be on the pictures Ford made available? Just curious on other opinions.

To me it looks like Ford may have digitally blacked out the area where the new independent rear suspension and electric drive should be. I suppose it could be some type of air dam to lower drag and or to protect motor from water and dirt, but it seems located too far back for that to be the case. It also looks too low and straight across.

If you think itís digitally blacked out, what could Ford be hiding?
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Old 11-14-2020, 04:27 PM   #112
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Getting back to the electric van, what do you guys think is going on at the rear where the suspension and drive motor should be on the pictures Ford made available? Just curious on other opinions.

To me it looks like Ford may have digitally blacked out the area where the new independent rear suspension and electric drive should be. I suppose it could be some type of air dam to lower drag and or to protect motor from water and dirt, but it seems located too far back for that to be the case. It also looks too low and straight across.

If you think itís digitally blacked out, what could Ford be hiding?
.
I wonder if all those images were created before the reveal so they put the black out there to hide the evidence for an independent rear. If you look at the eTransit website you don't see any of the same thing. Look at this pic:


None of them show blackout.
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Old 11-14-2020, 04:50 PM   #113
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I'm sure that they hid everything that they could.
After all: speculation is what drives these forums!
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Old 11-14-2020, 07:49 PM   #114
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I wonder if all those images were created before the reveal so they put the black out there to hide the evidence for an independent rear. If you look at the eTransit website you don't see any of the same thing. Look at this pic:


None of them show blackout.

Yes, thanks, makes sense. Some of the newer posted high-definition photos make it clear that ground clearance under rear end is pretty good, although there is a footnote stating pictures are computer generated or modified.

One detail of interest to me is that based on pictures, and some specs, it appears F-150 and Transit electric prototypes use different independent rear suspension designs. The F-150 IRS looks similar to the multi-link used on Expedition, while Transit specs call for a ďheavy-dutyĒ semi-trailing-arm independent rear suspension with coil springs.

Semi-trailing arm is simple, strong, and lower cost, and may also allow packaging under the relatively low floor of a Transit van. A challenge would be vertical height for the coil spring, but in one of the pictures it looks like Ford may have dropped the coil spring well below the wheelís centerline.

Just a guess on my part, but that large protrusion right next to rear tire of the Transit may be the coil spring (unless itís a shadow). Note that F-150 prototype appears very different.
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Old 11-14-2020, 08:01 PM   #115
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It makes sense that the F-150 and Expedition would share parts and designs.
Do the parts on the Transit look like what's on the Explorer?
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Old 11-14-2020, 10:19 PM   #116
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No. There are no pictures yet of the Transitís ďsemi trailing armĒ rear suspension, but they must be different.

The Ford web page lists the new RWD Explorer as having a ďMulti-link independent rear suspensionĒ (same type as Expedition), not semi trailing arm design like the electric Transit.

Semi trailing arm may not be as sophisticated as a multi-link, but itís got to be better for ride quality than a solid axle with leaf springs.

Below are pictures of electric F-150 prototype and also older Expedition rear suspension. The similarities can be seen. Keep in mind itís a prototype subject to possible change.

For what itís worth, the Expedition has a Rear Gross Axle Weight Rating of 4,380 pounds, quite a bit lower than existing SRW Transit T-350. That may explain the new 6,000-pound STA suspension for the eTransit. After all, it has to carry the load.
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Old 11-14-2020, 11:26 PM   #117
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Thanks for the info.
But it seems odd...
I would have almost bet money that Ford would have done some "parts bin engineering,"; in order to save some coin...
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Old 11-16-2020, 05:27 PM   #118
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Thanks for the info.
But it seems odd...
I would have almost bet money that Ford would have done some "parts bin engineering,"; in order to save some coin...
That would require Ford having usable parts in their bins, but the electric Transit is the very first vehicle of its kind at Ford as far as I know, so it seems very unlikely engineers had much existing components to work with.

In order to haul about 4,000 pounds of cargo in eTransit, Ford needed an independent rear suspension with around 6,000-pound capacity. Thatís equivalent to my E-350ís live rear axle which is rated at 6,084 pounds (limited by tires in my case).

Notice the eTransit is only available with Single Rear Wheels (at least for now) unlike gas Transits. While SRW limits cargo capacity, I expect it was more difficult to design an independent rear suspension that would work with duallies.

Anyway, Iím just glad to see additional research and development towards heavier-duty independent rear suspensions using single wheels. Both are huge steps towards future RVs that drive and handle a little more like SUVs and less like commercial trucks.
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Old 11-16-2020, 06:16 PM   #119
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Perhaps all of that extra bottom-end torque required something stronger...
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Old 11-16-2020, 06:26 PM   #120
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There is some speculation on the Mach-E forums that the Transit IFS is some way derived from the RWD drive module of the Mach-E.

Not sure I see that, however. Yeah the torque handling would be there but not the configuration nor the weight carrying capacity (Mach-E's cargo carrying capacity is like 700lbs or so).
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