ecoboost towing mpg.......
10-03-2011, 01:57 PM
#12
2011 FX4 EcoBoost...
Just did a run from Denver to Utah hauling a utility trailer with two moto's and gear. Probably about 1,600 pounds total trailer weight? Maybe another 600 pounds in the bed, so not a super heavy load.
Lots of mountain passes, higher altitudes, and climbing. Definitely not an ideal environment for maximizing fuel economy. Also, I typically cruised at about 9 over the limit most of the time, which meant I was usually between 75 and 85 mph.
The great news is the EcoBoost had awesome power, towing the (admittedly fairly light) trailer up steep high altitude grades with almost no impact to performance... And while I had it on cruise much of the time, I wasn't driving to optimize economy and wouldn't hesitate to put my foot into it to get past traffic quickly when needed.
Averaged about 13 MPG. Not great, but considering the speed/altitude/grades, more than acceptable.
End of the road...
Just did a run from Denver to Utah hauling a utility trailer with two moto's and gear. Probably about 1,600 pounds total trailer weight? Maybe another 600 pounds in the bed, so not a super heavy load.
Lots of mountain passes, higher altitudes, and climbing. Definitely not an ideal environment for maximizing fuel economy. Also, I typically cruised at about 9 over the limit most of the time, which meant I was usually between 75 and 85 mph.
The great news is the EcoBoost had awesome power, towing the (admittedly fairly light) trailer up steep high altitude grades with almost no impact to performance... And while I had it on cruise much of the time, I wasn't driving to optimize economy and wouldn't hesitate to put my foot into it to get past traffic quickly when needed.
Averaged about 13 MPG. Not great, but considering the speed/altitude/grades, more than acceptable.
End of the road...
10-03-2011, 02:05 PM
#13
Senior Member
Since our trucks are using "P" tires, the sidewall ratings are only at maximum PSI. So if you're loading the truck, air the tires up to whatever the maximum air pressure is on the tire in order to get the tire's full weight carrying ability. There is a loading chart - somewhere - that all manufacturers use, specifying tire pressure at various weights, but none of the manufacturers make it public.
For a max-tow truck with a 4,050 pound rear axle you're not going to be too far away the GVWR rating with maxed out air in your tires in any case.
If you pull into a rest area, always touch each tire - if it feels hot enough to scorch your hand, you're probably low on air or overloaded - in either case, adding more air is usually a good temporary fix.
For LT tires and truck tires, almost all manufacturers make the data public showing what the minimum and maximum PSI is for each type of tire and weight rating.
For a max-tow truck with a 4,050 pound rear axle you're not going to be too far away the GVWR rating with maxed out air in your tires in any case.
If you pull into a rest area, always touch each tire - if it feels hot enough to scorch your hand, you're probably low on air or overloaded - in either case, adding more air is usually a good temporary fix.
For LT tires and truck tires, almost all manufacturers make the data public showing what the minimum and maximum PSI is for each type of tire and weight rating.
10-03-2011, 06:05 PM
#16
Official Member: Vast RWC
09-26-2012, 03:26 PM
#17
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2012 Ecoboost with 1600 miles towing in Fl. Pulled my 20 foot v-nose 6.5ft interior trailer and averaged 8.4 mpg at 70 mph on 87 octane. 2007 Ram 5.7 avg 9.1 pulling same trailer. Granted the Ecoboost pulled it better but got lower mileage. I will try the 93 octane next time as we only have 87, 89 and 93 in Fl.
09-26-2012, 07:08 PM
#18
Senior Member
This is an interesting topic.
As some may already know, engine efficiency is typically measured in Brake Specific Fuel Consumption (BSFC) measured in lb/hr/hp. It's the amount of fuel an engine requires to make a certain amount of hp. The higher the number, the lower the efficiency. For every engine, some engineer has a map of load vs rpm vs BSFC.
Different from diesels, gasoline engine BSFC goes to pot at lighter loads. This is due to low manifold pressure and, thus, high pumping losses on the intake stroke (piston pulling against a vacuum). At some medium load of say, 50 hp (constant cruise speed) a lower displacement engine will have a lower BSFC (higher efficiency) than a larger engine because the smaller engine is running higher manifold pressure and has lower pumping losses (throttle is more open on a smaller engine to achieve the same power). This is why the 3.5 and 3.7 get better fuel economy at cruise than the 5.0, and the 6.2 is much worse.
However, when you get into boost, the turbo engine exhaust pressure (turbine drive pressure) starts ramping up. This, of course, leads to higher pumping losses and higher BSFC (lower efficiency). At full throttle and high boost levels, a turbo engine's BSFC can be 10% higher than a naturally aspirated engine. Keep in mind that a naturally aspirated engine is running near atmospheric intake and exhaust manifold pressures, minimizing pumping losses.
So, depending on what load you're running, a smaller turbo engine can range from 10% better to 10% worse fuel economy than a larger naturally aspirated engine. I don't think people tow at full throttle, so the turbo engine should run less than 10% worse economy.
I guess when Ford said "The fuel economy of a V6 and the power of a V8", they meant "The part throttle fuel economy of a V6 and the full throttle power of a V8".
As some may already know, engine efficiency is typically measured in Brake Specific Fuel Consumption (BSFC) measured in lb/hr/hp. It's the amount of fuel an engine requires to make a certain amount of hp. The higher the number, the lower the efficiency. For every engine, some engineer has a map of load vs rpm vs BSFC.
Different from diesels, gasoline engine BSFC goes to pot at lighter loads. This is due to low manifold pressure and, thus, high pumping losses on the intake stroke (piston pulling against a vacuum). At some medium load of say, 50 hp (constant cruise speed) a lower displacement engine will have a lower BSFC (higher efficiency) than a larger engine because the smaller engine is running higher manifold pressure and has lower pumping losses (throttle is more open on a smaller engine to achieve the same power). This is why the 3.5 and 3.7 get better fuel economy at cruise than the 5.0, and the 6.2 is much worse.
However, when you get into boost, the turbo engine exhaust pressure (turbine drive pressure) starts ramping up. This, of course, leads to higher pumping losses and higher BSFC (lower efficiency). At full throttle and high boost levels, a turbo engine's BSFC can be 10% higher than a naturally aspirated engine. Keep in mind that a naturally aspirated engine is running near atmospheric intake and exhaust manifold pressures, minimizing pumping losses.
So, depending on what load you're running, a smaller turbo engine can range from 10% better to 10% worse fuel economy than a larger naturally aspirated engine. I don't think people tow at full throttle, so the turbo engine should run less than 10% worse economy.
I guess when Ford said "The fuel economy of a V6 and the power of a V8", they meant "The part throttle fuel economy of a V6 and the full throttle power of a V8".
Last edited by engineermike; 09-26-2012 at 09:56 PM.
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byeboty (09-26-2012)
09-26-2012, 08:35 PM
#19
thanks for posting this. for some reason, many people dont understand that power isnt free. Many of the eco boost customers are complaining that their milage isnt what is advertised. Part of this isnt their fault as there is no real way for them to know weather they are boosting or not because there is no boost gauge on their trucks. But the bottom line is if you want v8 power from a boosted v6 you will get worse fuel economy than a NA v8. it is a mathematical certainty. it all has to do with volumetric efficiency. it is simple, a twinturbo v6 will not be as fuel efficient as a v8 making the same power. this has been tested and proven by the company for decades.
09-26-2012, 08:48 PM
#20
Originally Posted by engineermike
This is an interesting topic.
As some may already know, engine efficiency is typically measured in Brake Specific Fuel Consumption (BSFC) measured in lb/hr/hp. It's the amount of fuel an engine requires to make a certain amount of hp. The higher the number, the lower the efficiency. For every engine, some engineer has a map of load vs rpm vs BSFC.
Different from diesels, gasoline engine BSFC goes to pot at lighter loads. This is due to low manifold pressure and, thus, high pumping losses on the intake stroke (piston pulling against a vacuum). At some medium load of say, 50 hp (constant cruise speed) a lower displacement engine will have a lower BSFC (higher efficiency) than a larger engine because the smaller engine is running higher manifold pressure and has lower pumping losses. This is why the 3.5 and 3.7 get better fuel economy at cruise than the 5.0, and the 6.2 is much worse.
However, when you get into boost, the turbo engine exhaust pressure (turbine drive pressure) starts ramping up. This, of course, leads to higher pumping losses and higher BSFC (lower efficiency). At full throttle and high boost levels, a turbo engine's BSFC can be 10% higher than a naturally aspirated engine. Keep in mind that a naturally aspirated engine is running near atmospheric intake and exhaust manifold pressure, minimizing pumping losses.
So, depending on what load you're running, a smaller turbo engine can range from 10% better to 10% worse fuel economy than a larger naturally aspirated engine. I don't think people tow at full throttle, so the turbo engine should run less than 10% worse economy.
I guess when Ford said "The fuel economy of a V6 and the power of a V8", they meant "The part throttle fuel economy of a V6 and the full throttle power of a V8".
As some may already know, engine efficiency is typically measured in Brake Specific Fuel Consumption (BSFC) measured in lb/hr/hp. It's the amount of fuel an engine requires to make a certain amount of hp. The higher the number, the lower the efficiency. For every engine, some engineer has a map of load vs rpm vs BSFC.
Different from diesels, gasoline engine BSFC goes to pot at lighter loads. This is due to low manifold pressure and, thus, high pumping losses on the intake stroke (piston pulling against a vacuum). At some medium load of say, 50 hp (constant cruise speed) a lower displacement engine will have a lower BSFC (higher efficiency) than a larger engine because the smaller engine is running higher manifold pressure and has lower pumping losses. This is why the 3.5 and 3.7 get better fuel economy at cruise than the 5.0, and the 6.2 is much worse.
However, when you get into boost, the turbo engine exhaust pressure (turbine drive pressure) starts ramping up. This, of course, leads to higher pumping losses and higher BSFC (lower efficiency). At full throttle and high boost levels, a turbo engine's BSFC can be 10% higher than a naturally aspirated engine. Keep in mind that a naturally aspirated engine is running near atmospheric intake and exhaust manifold pressure, minimizing pumping losses.
So, depending on what load you're running, a smaller turbo engine can range from 10% better to 10% worse fuel economy than a larger naturally aspirated engine. I don't think people tow at full throttle, so the turbo engine should run less than 10% worse economy.
I guess when Ford said "The fuel economy of a V6 and the power of a V8", they meant "The part throttle fuel economy of a V6 and the full throttle power of a V8".
Would love to see this stickied as an explanation for "why does my EB get worse mpg than my old XXXX when towing?"
I'll also add that it takes the same HP to move the same load. So it shouldn't be surprising to people that you get the same mpg towing a decent load.
I course, when not under boost it's a whole nother ball game.
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engineermike (09-26-2012)