Sweet spot for 4.10 gears
I've got the bullet proof vest on, shields up and ready. If this has been asked countless times before, I apologize in advance. What is the sweet spot for towing if truck has 4.10 gears and diesel? Te...
Forum Discussion
The 2017 Powerstroke makes peak torque of 925 lb ft at 1600 rpm. At 2800 rpm where the peak hp is obtained the torque has dropped to 825 lb ft. So for every 100 rpm the engine pulls down from 2800 the torque rises by about 8 lb ft.
Based on this I would expect the engine to be able to produce about 905 lb ft of torque at 1850 rpm. This means that at 1850 rpm the engine us capable of producing about 320 crankshaft HP.
Diesel fuel contains about 55 hphrs per gallon. So for an engine to operate at 40 % efficiency and produce 320 hp for one hour it would require 14.5 gallons of diesel.
In other words the Powerstroke is capable of burning 14.5 gallons of fuel per hour at 1850 rpm.
If you are travelling 60 mph and using 14.5 gallons of fuel per hour you are getting 4 miles per gallon fuel economy.
Obviously the Powerstroke does not have to be running anywhere near 1850 rpm to produce the power required to tow a typical rv down the highway at 60 mph.
Now consider the speed the truck can travel while pulling your trailer up the type of hill you expect to encounter in your travels:
Say your combined weight is 29000 lbs. The rear wheel hp required to overcome wind and rolling resistance on level ground at 45 mph is approximately 70 Hp.
The rear wheel power required to lift the 29000 lbs up a 7% incline at 45 mph is exactly 243 rear wheel hp.
If the drivetrains is 75% efficient the engine would need to produce (70+243)/.75 HP to pull a 29000 lb truck and trailer up a 7% grade.
(70+243)/.75 = 417 hp.
It is reasonable to expect the Powerstroke to be able to produce 417 crankshaft HP so long as it is running between 2600 and 2900 rpm.
With 3.55 gears the engine would be running 2594 rpm In 3rd gear at 45 mph.
With 4.10 gears at 45 mph the transmission would be in 4th and the engine would be running at 2266 rpm. The truck with 4.10 gears would not be able to pull the hill in 4th gear so it would have to slow down to 42 mph where the driver could force a downshift and then maintain 42 mph at 2800 rpm in 3rd gear.
If you will be pulling a trailer heavier than 22000 lbs or hills steeper than 7% than 4.10 gears could possibly become advantageous over 3.55 gears. For most RVs the 3.55 gears are a better choice.
Based on this I would expect the engine to be able to produce about 905 lb ft of torque at 1850 rpm. This means that at 1850 rpm the engine us capable of producing about 320 crankshaft HP.
Diesel fuel contains about 55 hphrs per gallon. So for an engine to operate at 40 % efficiency and produce 320 hp for one hour it would require 14.5 gallons of diesel.
In other words the Powerstroke is capable of burning 14.5 gallons of fuel per hour at 1850 rpm.
If you are travelling 60 mph and using 14.5 gallons of fuel per hour you are getting 4 miles per gallon fuel economy.
Obviously the Powerstroke does not have to be running anywhere near 1850 rpm to produce the power required to tow a typical rv down the highway at 60 mph.
Now consider the speed the truck can travel while pulling your trailer up the type of hill you expect to encounter in your travels:
Say your combined weight is 29000 lbs. The rear wheel hp required to overcome wind and rolling resistance on level ground at 45 mph is approximately 70 Hp.
The rear wheel power required to lift the 29000 lbs up a 7% incline at 45 mph is exactly 243 rear wheel hp.
If the drivetrains is 75% efficient the engine would need to produce (70+243)/.75 HP to pull a 29000 lb truck and trailer up a 7% grade.
(70+243)/.75 = 417 hp.
It is reasonable to expect the Powerstroke to be able to produce 417 crankshaft HP so long as it is running between 2600 and 2900 rpm.
With 3.55 gears the engine would be running 2594 rpm In 3rd gear at 45 mph.
With 4.10 gears at 45 mph the transmission would be in 4th and the engine would be running at 2266 rpm. The truck with 4.10 gears would not be able to pull the hill in 4th gear so it would have to slow down to 42 mph where the driver could force a downshift and then maintain 42 mph at 2800 rpm in 3rd gear.
If you will be pulling a trailer heavier than 22000 lbs or hills steeper than 7% than 4.10 gears could possibly become advantageous over 3.55 gears. For most RVs the 3.55 gears are a better choice.
