Gas Mileage and Axle Ratios

[Jim R]

I am looking at buying either a 2008 king ranch f-250 super duty single rear wheel 4x4 with the turbo diesel automatic with the 3.73 rear or the f-450 dually turbo diesel 4x4 with 4.10 rear. What is the difference in engine rpm and gas mileage will be around town and on the highway unloaded?

Is there a website I can go to and plug in the engine and axle ratios at differing speeds that shows engine rpm and the approximated mpg consumption?

 

[DaveBen]

You should get about 10% better mileage with the 3.73 gears, but that is NOT an absolute. Other factors will influence your mileage like tires and air pressure. 4.10/3.73 = .909 or 90% with 4.10 vs 3.73.

Dave

 

[Nasty]

weight

would also be an issue I would think...gotta be considerable difference in those 2 rigs. Being picky but...gas mileage will be terrible on either unit; diesel will probably be better.

Be well!

BTW..my units use an almost identical amount of fuel on our runs (800+ miles) I had ordered the 3:73s figuring them to be easier on fuel. I also just installed a SCT which Tadd programmed for me...will post on that when I have more miles on it

 

[Strut61]

Sorry but first off you cannot buy an 08 F450 with 4:10's, they only come equipped with 4:30 or 4:88's.

Mine has 4:88's and here is the mileage I'm seeing so far:

Realize these numbers are a combination of rural and highway driving (NO towing). Also, this reflects majority of the driving between 55 and 70 mph (I did run on cruise at 75 for about 60 mi on one tank). No short trips, no stop and go driving.

1st; 309.6 miles 29 gallons = 10.67
2nd; 202.2 miles 18.4 gallons = 10.98
3rd; 155.1 miles 13.3 gallons = 11.66
4th; 235.4 miles 20.7 gallons = 11.37

Total; 902.3 miles / 81.4 gallons = 11.08 average mpg