Hello I' am the owner operator of a 2005 Mack granite tri axle dump. It has a AI-375 engine with an allison 6spd auto. This truck drinks diesel like theres no tommorow. I work with a broker in my area primarily and get paid by the load so I really can't be soft on the pedal but I don't abuse the pedal to much. I really just do the speed limit but the speed limit in my area is 70mph on many of the big highways. Also the distances im driving are are about 110-15miles round trip for 1 load. So im in the process of getting aluminum wheels all around for the truck maybe an aluminum bed but thats years down the road and I need help now. I have recently been looking at maybe a propane injection system when I noticed a Hydrogen Fuel Injection system made in canada. http://www.chechfi.ca/
But I don't know to much about the HFI system to justify if its worth the cost. So does anybody out there have any other suggestions that might help me out....

 

I suggest you start using fuel instead of gas.

 

we have 15 of them.. 10 are autos and get 3.5 mph. the other 5 are 6 speeds and get 5.5.. a heavy foot off the light drinks a lot of fuel. the autos just dont get good mileage no matter what you do

 

I would be selling the truck before I spent money on aluminum.

 

Whats wrong with upgrading to aluminum wheels or upgrading your bed?

 

In my opinion automatics are just JUNK it takes the fun and control factor out of driving a truck!!! I feel the same way as well in a personal vehicle!

 

What control do you feel that you lose.. and of course "fun" really must be something subjective here :lol:

 

I just feel more in control with a manual over an automatic. After driving an automatic car for over 2 years and now currently driving a manual 89 Ford F150 2wd pick up I don't want to go back into an automatic.

 

I agree 100%. I recently test drove a 2008 Ford Focus SES with a 5 speed manual tranny and 3.83 axle ratio (140 hp). This thing was flying! After my 2007 Focus with a 4 speed auto driving this car I felt like I was a race car driver This new Focus even has a gadget on the dashboard to tell you when to shift: when your RPM are high or low enough the green arrow lights up to indicate you should shift into up (the arrow points up) or down (the arrow points down). And of course this manual tranny is a synchro which makes it extremely easy to change gears.

 

A lot of people are under the impression that the posted MAXIMUM LEGAL SPEED is the speed you should be driving at. My CAT C15 engine can develop 500 hp at 1600 rpm but I'm driving - depending on the terrain and the load - either at 58, 59 or 60 miles per hour. Why? Because at these speeds my engine turns at 1,300-1,350 RPM which is the best RPM for fuel mileage with my CAT. And I"m passed by guys who do 70 or 75 miles per hour but guess what - they pass me more than once!!!

I suggest you find out what your engine best fuel mileage RPM is and stop following the crowd. Drive at the speed that's best for your engine and accelerate slowly from lights. If the best engine speed translates into a road speed that's too low for your liking - you might look into changing your rear axle ratio or maybe switching to taller tires. ENGINE RPM AT 60 MPH = Axle ratio x Top gear ratio x Tires revs per mile.