Try running some low rolling resistance tires. That may help get you up closer. Last street 5.0 I have driven was a 93 lx 5sp with 2.73. I dont think that we came close to 30mpg. Stayed around the 24mpg on the hwy. We were never trying to optimize fuel economy.
There is going to be a sweet spot where the engine is not lugging and not spinning too hard to the point to reduce fuel economy. You will have to experiment with different hwy speeds.
Reducing rotating mass in the engine and drivetrain will help. Crankshaft scrapers and windage trays will aid all of this.
Then you have to ask yourself at what point does all of these mods actually pay for the fuel economy gained?
There is going to be a sweet spot where the engine is not lugging and not spinning too hard to the point to reduce fuel economy. You will have to experiment with different hwy speeds.
Reducing rotating mass in the engine and drivetrain will help. Crankshaft scrapers and windage trays will aid all of this.
Then you have to ask yourself at what point does all of these mods actually pay for the fuel economy gained?