Something different Building for MPG.

AdamЯ;254797 said
Dave, Your motor is very close to min. Only difference is mine has worked 302 heads with 1.88/1.60 valves instead of the Magnums and currently has a torker intake. Im still up in the air with what intake/carb Im going to run and if Im going with Headers or manifolds.

What year is your Dakota ? Mines a 98 Sport, club cab with 391s and 31X10.5-15s, 3.9L auto. The millage is no were near as good as yours.

Mine is a 99 Dakota SLT, Club Cab, 4x4 with the offroad package which includes the 3.92 gears and 31x10.5-15's and I have the 3.9 v6 auto.

I have made a few mods to improve perfromance and economy.
1. The single biggest improvement was taking the snorkel off the air box and running a piece of 4" flexable hose through the core support next to the radiator and using a K&N air filter in the stock box. This provides a true cold air intake. Tried one of those e-bag systems with the cone filter but it just sucked hot air from under the hood and was worse than the stock setup.
2. I relocated the inlet air temp sensor from the side of the manifold to the air hose into the throttle body. The truck used to get real sluggish on hot days due to temperature soak of the sensor. Now it is less impacted and provides the ecm a signal more representative of the air coming into the engine.
3. I have been using a cat back exhaust on the truck for the past 6 years. The flowmaster system finally rusted out and I just replaced it a couple of weeks ago with a Dynomax System. Even though the pipes in and out of the muffler are 2.5" in diameter from the factory the stock muffler necks down to less than 2" inside.
4. Synthetic fluids in the both diffs and the transfer case.
5. I still run 31x10.5 tires but I use ones with a street tread. My only off road driving is on the beach and a street tread actually works better than an all terrain tread on sand. I will need to get tires again before next winter and I think this time I will get 265/75-15's. These are esentially the same size but there are more choices in street oriented tread patterns.