Originally Posted by logistix
1. Turn the boost up on the turbo
2. Use a methanol injection kit from snow performance (hit the spray switch manually while going up a big hill or "as needed")
3. Weight reduction. (Plastic gas tank, lighter weight building materials, this is a stretch though since you'd need to shed around 1,000 pounds to notice a difference. And then when you start building and remodeling, you add the weight right back to it!
4. Heat treat/Harden the transmission gears and add a tranny intercooler to handle #5 below
5. Port and Polish your engine out to like 6.3 liters or something. This is a lot of work.
#1 is free
#2 is cheap and safe
#3 is personal preferance
#4 and #5 are pricey and personal preferance
You could look into changing your rear end axle gear, but higher rpm's on the highway = using more fuel (good for race cars, not so good for a school bus) I would just be happy with the way your bus is now. You aren't hauling 10 people and a trailer with a truck on it everywhere you go...
I'm just going to chime in about #1 & 5, and the ending:
-Turning up the boost on the turbo wont add power. It just makes a choke point when it's making higher power, and EGT goes up higher than it normally would if the wastegate is not even messed with. Adding fuel on a diesel makes more power.
-porting & polishing doesnt add displacement, it just helps the air get it & out faster & easier. There are ways to bore & stroke a 5.9, but for the trouble & expense, you could swap in an 8.3 C series for less cash. Those can be hot rodded too.
-they were talking about gearing the rear to lower the highway rpm. Lower RPM= better mpg.