[Dale_R]

Quotes excerpted from totallandscapecare.com article, The Future of Propane in Lawn Care -

"Pickup gas engine technology is advancing rapidly with both turbocharging and direct-fuel injection being applied to increase both power and fuel economy. A prime example of this new direction is Ford’s EcoBoost line of engines; small displacement, high-output configurations that deliver excellent fuel economy when lightly loaded."



"But the engines suffer on the fuel-economy front when subjected to medium- to high loads, such as towing trailer, as is the case with the 3.5L F-150 EcoBoost."


"According to Michael G. Ross,
 Program Manager 
for the Southwest Research Institute, dynamometer testing (with PERC funding) on a Ford 3.5L EcoBoost engine showed the potential for significant improvements in engine efficiency at medium to high loads when the engine is boosted. “Under boosted conditions, the engine is very knock-limited on gasoline, especially regular gasoline,” Ross explains. “To control knock when running on gasoline, the spark timing is retarded up to 20 degrees, which causes the exhaust temperature to increase significantly.”
Ross says under those high-load conditions, the engine dumps up to 30 percent in excess fuel to reduce the exhaust temperature in order to protect the turbocharger and catalytic converters. All that fuel is wasted. This is why the fuel economy for the EcoBoost suffers so much when towing."




Never having owned a turbocharged vehicle, I am wondering how to manage gas mileage effectively. Obviously, high octane fuel will help when heavily loaded, as will maintaining low manifold pressures as much a possible.


Can anyone add specific steps to take for fuel economy? At what manifold pressure do the turbochargers kick in? Anyone know?

 

[VanMan]

This one is going to be fun

I plan on buying a 3.5L eco in a mid- roof LWB cargo. I am one of the biggest ecoboost guys here.

Manifold pressure reads atmosheric preussure when the engine is off (29.92 @ sea level/standard day) so if you have a manifold pressure gage reading in inchs/mercury look at it before you start and anything above that is boost.
The eco does not come with a boost gage, but plenty of aftermarket ones.
I plan on using a aircraft manifold pressure instrument (I have them) but a hotrod boost gage is cheaper.
I plan on using premium fuel to take advance of the ECU to give me the best spark advance.
If you have not driven one (I have) the power is VERY addictive in a Transit
The boost comes in fast, about 2,500 rpm so it will take some work to get the fuel mileage advantage out of it.
I could go on, I am NOT buying this for fuel mileage, but can get it out of driving it VERY carefully. 20+ hwy

 

[Dale_R]

Thanx, VanMan. The low roof, beige van with EcoBoost startled me a bunch when I took off on the first little short straight out of the parking area at Dearborn! Wow!!

 

[VanMan]

Just not to scare anyone, the 20+ claim will require cruise control set @ 70
I will map @ 70, 75, 79. above 80 the cops get involved,
I plan on larger dia. tires and haul light loads.
see what I get get and so be it

This is a 400hp de-tuned engine, I want some of it back (310 in transit, 385 in SHO awd cop cars)

 

[Chance]

SHO and cop cars generally don't tow. At least not a 7000-pound trailer like a work van may be ask to do. 400 HP may be nice to run a quarter mile for a few seconds but I think pulling a large trailer for hours at a time is much harder on engine. That's probably why Ford derated van power output.


Regarding OP question about when turbos "kick in", I prefer to think of turbos as more of a continuously variable operation rather than a discrete on-off operation.

 

[VanMan]

SHO and cop cars generally don't tow. At least not a 7000-pound trailer like a work van may be ask to do. 400 HP may be nice to run a quarter mile for a few seconds but I think pulling a large trailer for hours at a time is much harder on engine. That's probably why Ford derated van power output.


Regarding OP question about when turbos "kick in", I prefer to think of turbos as more of a continuously variable operation rather than a discrete on-off
operation.

I agree 100% with your comments, I won't tow, but want the hitch and tow/haul mode.
Turbo operation will be varible on load, was giving a example off the dyno torque charts.
Funny that alot of F150 guys said that the perforamce advantage of premium gas was the reduction of weight of your wallet if you drive normal unloaded.
Anybody who wants to control how this thing (eco) drinks, install and drive with a boost gage.

 

[Flex2Transit]

Don't look at tuning only for more HP, as in go faster... because racecar.

Tunes can be mapped that enhance desired traits. An increase in fuel economy will be a target of tunes.

At the Flex.net forum, there are EB Flex's running impressive quarter miles and some sipping fuel. Torrie is the tuner big on that board. I'm trying to invite some resources from other forums who could benefit this forum.

 

[VanMan]

Don't look at tuning only for more HP, as in go faster... because racecar.

Tunes can be mapped that enhance desired traits. An increase in fuel economy will be a target of tunes.

At the Flex.net forum, there are EB Flex's running impressive quarter miles and some sipping fuel. Torrie is the tuner big on that board. I'm trying to invite some resources from other forums who could benefit this forum.

Well said
Alot of tuning that could help its drinking problem

My Hotrod view is limited to just a few people needs

 

[sparks]

Did a test drive on a 3.7 yesterday and the power won't cut it in the hills of Pennsyltucky. If an empty van is lackluster, shudder to think what a loaded one would be like.

Planning to visit another dealer and drive the ecoblast.

My question is this: was the EB downrated in the van for mileage or drivetrain limited considerations?

If the beast is modified back to F150 specs, will it break stuff or twist the frame or something?

Other than that, it drove well, and may be able to squoosh my 6'2" height for better mpg and less crosswind sensitivity (med vs high roof)

Half tempted to cut a hole in the roof so I can stretch

 

[Brad]

My reasoned guess is that Ford tried to hit the sweet spot with respect to *overall* customer satisfaction. Yes, the engine could no doubt be tuned for greater horsepower. But there are likely many more (potential) owners, especially in the commercial van segment, interested in reasonably zippy performance with decent mpg, than those needing to get 2nd and 3rd gear scratch with the consequence of poorer mpg.

I think they made the right trades maximizing overall customer satisfaction.

 

[Mc2guy]

Also, the methodology for HP rating in commercial vehicles is different than passenger vehicles. The 310 HP rating in the transit is not the same as 310 in a passenger car, it's more. To compare directly would require a Dyno but it's closer to 330 than 310.

 

[Chance]

My 2 cents.....

From my perspective the thing to always keep in mind is that it takes fuel to make power, and likewise it takes a lot of fuel to make a lot of power. There is no free lunch. Maybe less expensive but not free.

Most modern gasoline engines have a Brake Specific Fuel Consumption of about .40 to .45 pounds of fuel per horsepower per hour when operating in their efficiency sweet spot. Even so, when an engine is making 200 HP it will likely be burning about 90 ponds of gasoline per hour, which is around 15 gallons of gasoline per hour.

So if you are towing and going up a hill that makes your engine produce 200 HP to hold 60 MPH, then 60 MPH/15 GPH equals 4 MPG. an that's assuming you can keep the engine near its efficiency sweet spot.

Fortunately the EcoBoost technology yields a broad efficiency map covering a wider range of Brake Mean Effective Pressure (it's a way to measure torque) so it's easier to remain in efficient engine RPM vs. torque zone, but regardless it takes lots of fuel to make even 200 HP. Push it to 300 HP and you'll be burning well over 20 gallons an hour.

The only trick I can see to using less gas is to use less power. But most of us know that intuitively. On the other hand if you hot rod you'll pay at the pump. Ultimately it's more about what the driver does than what the engine can do towards saving fuel.

 

[sparks]

Would be neat if someone could gin up a chart of hp required vs speed (which should equate roughly to mpg vs speed, allowing for system losses / offset for idle)

Anyone have mpg data at various fixed speeds? Should only take 3 data points to define the curve.

 

[Chance]

Would be neat if someone could gin up a chart of hp required vs speed (which should equate roughly to mpg vs speed, allowing for system losses / offset for idle)

Anyone have mpg data at various fixed speeds? Should only take 3 data points to define the curve.

I have done just that but for my van which is a Ford E-350 with V10 engine. I'm not home right now and don't have access to data, but to the best of my recollection it uses right around 50 HP at steady 70 MPH. At that "steady" speed I get 15 MPG. Because the engine is so lightly loaded it's below its efficiency sweet spot.

For my van the curve changes roughly 1 MPG for every 5 MPH in that speed range. So in theory approximately 16 MPG at 65 MPH, 15 MPG at 70 MPH, and 14 MPG at 75 MPH. It's not a straight line so it can't be extrapolated much beyond that in direct proportion to speed.

My van's engine is so oversized that when driving slowly the MPGs don't increase as much as it could if it had a smaller engine. That's why 3.7L is so much better than 6.8L for anyone planning to take their time and drive slowly.

 

[sparks]

Would not expect it to be a straight line. Should be an exponential.

IIRC, Excel can do some curve fitting and give goodness of fit data.

 

[Chance]

Would not expect it to be a straight line. Should be an exponential.

IIRC, Excel can do some curve fitting and give goodness of fit data.

Aerodynamic drag does go up exponentially with speed, but fuel economy of most vehicles as a function of speed generally follows a curve shaped similar to this one that I copied off Internet. The values can be very different but the general shape normally follows the same pattern. It starts low (obviously 0 MPG at 0 MPH) and improves up to an optimum speed at which point it levels off and then it starts to decrease as speed continues to go up.

If engines remained equally efficient at all vehicle speeds, fuel economy would be very high at low speeds -- like at 10 or 20 MPH. But gasoline engines become so inefficient at low loads that MPGs don't improve as much as they could otherwise. And that's where the EcoBoost should shine compared to naturally-aspirated engines of similar power.

Using my van as an example, I get close to 13 MPG at 80 MPH, and because road load (referring to force and not power) is reduced in half at 50 to 55 MPH, my steady-state fuel economy could double to around 26 MPG, but additional engine inefficiency limits economy to no more than 17 or 18 MPG. It would take a small I-4 engine to obtain that 26 MPG at 50 to 55 MPH. A small EcoBoost V6 would not be as efficient as a 2-liter I-4 at a steady 50 to 55 MPH, but it will be a lot better than a 6.8L V10.

 

[Chance]

Curve mentioned for above post:

 

[sparks]

Makes sense. Thank you for posting the curve. Will be interesting to see how the smaller ecoboost (from the 2015 f150) would do in a camper transit.

 

[Chance]

Makes sense. Thank you for posting the curve. Will be interesting to see how the smaller ecoboost (from the 2015 f150) would do in a camper transit.

If we see the 2.7L EcoBoost in a large camper van I would expect very little difference in fuel economy at typical highway speeds of 70 to 75 MPH compared to the 3.5L EcoBoost or the standard V6. That's because the van's power requirement is high enough that the other engines can be geared to operate in efficient zone at that van speed.

Downsizing from 3.5 to 2.7 EcoBoost will make a bigger difference in an F150 because it uses less power when not towing, which is the way most F150s are driven most often. Downsizing from 3.5 to 2.7 EcoBoost will make an even bigger difference when compared on cars or crossovers that use even less power.

Because Ford can't change the physics of what it has to work with, I would expect them to use the 2.7 EB in other vehicles first before the Transit. In a large camper van it should only make a significant difference at low speeds. Basically the smaller EcoBoost should extend the curve above to the left but make little difference to the right. It will make it broader which is a good thing but won't save that much fuel in real world because most of us don't cruise at 40 MPH for long distances.

EB engine Brake Specific Fuel Consumption curves published by Ford regarding technology gives us a good idea on what we can expect. Curves are hard to follow though, and why I hesitate posting them. They may confuse the topic more than help.

 

[sparks]

Never too old to learn something new.

These helped me understand the curves a bit.

http://www.umtri.umich.edu/content/Dan.Kapp.Ford.pdf

How to Go Fast Faster: The Math Behind Turbocharging. Part 3b: Brake Specific Fuel Consumption (BSFC) | Take me beyond the Horizon

Have not yet found actual curves for the 3.5l Ecoboost - any links out there?