Engine/Transmission (1998.5 - 2002) fuel economy/gear ratio

[johnharris]

Dose a gear ratio (4:10 vs 3:55) give different fuel economy (MPG). If so what would the difference be?:{

 

[Ramboy]

I'm sure the difference would vary from truck to truck but the 3. 55 will give better economy at a given highway speed.

 

[cmckinney]

Unless you consistently pull a load go with the 3. 54 rear end b/c you will get better fuel mileage. With the CTD you have plenty of torque to still pull comfortably. The 4. 10 are great to pull with but decrease your fuel mileage at Hwy speeds.



-CM

 

[Tomeygun]

i went with the 4. 10's because of my future plans to run a 38 inch tire, then the ratio will be just right,



and the cost now is much less then after the factory!!



with 3000 miles, i got 17. 5 mpg on last tank

 

[andrewkoperdak]

Johnharris,

I have a relatively light 3/4 ton at just 6000 pounds. I have the 3. 54 ratio with a five speed. I have Stage 3 injectors and I get ~20 mpg around town and 22 on the road empty. I rarely drive faster than 70 mph. I just got done with a vacation pulling my 5th wheel. At a GCVW of 11550 I got 16 mpg running up the west coast from San Diego to Seattle with average speed ~ 60mph. I run 2000 RPM at 70 and 1725 at 60 mph.

Hope that helps.

Andy

 

[klenger]

The difference is less than you might think. I get 18 -20 MPG with 4. 10's driving on the highway in the city. For towing my 10K 5er, the 4. 10's are great. For speeds 55 or less around town, I suspect that the 4. 10's don't effect the milage at all, and may even improve it.

 

[Tomeygun]

klenger:



how many miles do you have on your truck?



what was your MPG when it was new?

 

[BigDan]

I've been getting about 16. 5mpg on mine with 5K on the OD. I'm normally going 70-75mph at 2300RPM. I would probably get alot better at 60mph at 2000rpm.

 

[klenger]

I currently have 17K on the truck. I'm gussing that 4000 - 5000 of that is towing. I was getting about 16 - 17 MPG when it was new. It started to loosen up about 9,000 miles.



If I had to replace the truck, I would seriously consider the 4. 10's again. I understand in '03 that 3. 73 will be available.



If I had 3. 54's, I'm not sure how I would tow. 65 MPH in 6th lugs the engine too much, and RPMs would be about 2500 in 5th at 65 MPH. With the 4. 10's, I'm towing at 65 MPH at 2200 RPM. I have the stock 265 tires, and engine is and will stay stock for now.



I think that a lot of people don't realize how little time you might spend on the highway at high speeds. I have 17,000 miles on the truck and about 480 total hours on the engine. That works out to about 35 MPH average, much of that on the intestates in the city.

 

[LarryG]

Originally posted by klenger

The difference is less than you might think. I get 18 -20 MPG with 4. 10's driving on the highway in the city. For towing my 10K 5er, the 4. 10's are great. For speeds 55 or less around town, I suspect that the 4. 10's don't effect the milage at all, and may even improve it.

I just got back from a vacation in the Canadian Maritimes, put on about 1900 miles, didn't do over 55 most of the way, running a lightly loaded '02, 4:10, auto, stock and averaged 23. 46 mpg and diesel is the least expensive fuel up there(by about 6-8 cents CDN/litre). I'm happy!