Boost increase & mileage/power correlation

[Mark Rinker]

I recently turned up the boost slightly on my '02, in search of the optimal setting for power and mileage. Power responded nicely, but it appears that mileage may have taken a hit. Too soon to tell, until an average settles out, over 10 or more tankfuls.

Observation: If boost is too low, black smoke is apparent, performance drops and and fuel economy suffers.

Question: When boost is too high - what is the best indicator? Can it be best measured in decreased economy?

[Kennedy]

It could be that you are increasing drive psi and there's not enough heat energy to increase boost. Hard to say. There's so many factors the biggest being fuel quality.

Try a Cold front and see how your mpg goes.

[Mark Rinker]

Good idea. With the mild winter, I haven't strapped one on, but will try one for a few tankfuls. Winter blend fuels might also be skewing my results.

The power increase is significant - feels like I found another 10-15hp and it comes in quick, not much RPM needed to roll truck, trailer, 10,000# from a dead stop to 60mph. So much in fact that you have to 'de-fuel' with your foot or the drives break loose searching for traction around peak torque in 3rd gear.