I had posted about my fuel economy numbers in another thread quite a while ago. Here's an excerpt from that post telling about what kind of fuel economy it is possible to get with the right mods:
I have a half ton 98 Dodge Ram 4x4 with the 5.2 liter magnum V8. The tires I'm currently running are wild country mud terrain MTX, size 265-75-R16. These are load range E. My truck has the 3.92 gear ratio 9.25" Dana rear end. It gets 26-27 mpg highway at 64-66 mph. It averages 18-19 mpg during most city driving. I have modified the engine and exhaust system for maximum fuel efficiency and increased power.
The modifications I have made are as follows:
) Removed thermostat completely, added supplemental E fan to help keep engine operating temps in the 125 - 139 degree range.
) Bosch platinum 4 plugs several heat ranges hotter than stock to work with colder running engine.
) Aftermarket MSD ignition box
) 8 mm spark plug wires for increased spark energy
) Ram air cold air induction with K&N filter
) JBA shorty headers into true dual exhaust, 2" pipe,(one pipe hooks to each header and continues to rear bumper) with no converters and no mufflers.
) Aftermarket oil cooler with fan
) Amsoil synthetic oil & lubricants
) Custom tune to work with the changes I have made, including 4 degrees of timing advance, custom spark and A/F mixture curves depending on throttle position.
The thing to take from this is that not everyone will be able to get numbers like these. They are dependent on the modifications I have made to the engine, air intake system, and exhaust system, with a custom tune to work with these mods. The best mileage is achieved driving at at the ideal speeds, in a truck in excellent mechanical condition with low mileage (62,400 I believe) and using synthetic lubricants. In that narrow band where it seems power and fuel economy intersect in just the precise amount, I do enjoy really decent mileage with my truck. However, change something in the equation, say driving at 80 mph on a long trip rather than 65, and I average closer to 17-18 mpg. In city driving, if I'm caught in heavy traffic, and don't get up over 40 mph, with frequent stops and a lot of idling, my city figures are much closer to stock at around 15 mpg. If you have a truck in good condition, and been recently rebuilt or dosent have a lot of miles, I'd say go for it and try some of these mods if you want to save $$ on gas in the long run. I did most of the work myself, and it didn't cost that much, and if I drive her nice on long trips, I can get 100+ miles more out of a full tank compared to the stock figures.
Dave
