Gordy-TC
Senior Member
When is the mileage the worst? The C7 isn't the biggest engine out there and you may just be overworking it, giving you the bad results.
For example, I got better fuel mileage pulling a heavy trailer with a 454 equipped dually crewcab then I do pulling a smaller trailer with my new 5.3L 2010 Silverado.
This is why I put a C15 in my Freightliner Century, that is soon getting converted to a motorhome.
For example, I got better fuel mileage pulling a heavy trailer with a 454 equipped dually crewcab then I do pulling a smaller trailer with my new 5.3L 2010 Silverado.
This is why I put a C15 in my Freightliner Century, that is soon getting converted to a motorhome.
Gordy-TC
Senior Member
The C7 is 7.2 liter or 441 cu in
The C15 is 15.2 liter or 928 cu in
My C15 is set to 475hp 1650 ft lb torque. A 300 hp C7 has max 860 ft lbs torque.
Notice that even though hp is up approx 50%, the torque is double. Torque takes you up the hill.
My Century Freightliner @55,000 lbs total weight pulls a 8.5% grade easily at 60mph and didn't overheat in the summer months.
Fuel mileage is around 8.5 to 9mpg on the highway which I find acceptable for this much engine. Some say mileage will go up with a few more miles on it but to date it has 27000.
May look at "chipping it" down the road.
The C15 is 15.2 liter or 928 cu in
My C15 is set to 475hp 1650 ft lb torque. A 300 hp C7 has max 860 ft lbs torque.
Notice that even though hp is up approx 50%, the torque is double. Torque takes you up the hill.
My Century Freightliner @55,000 lbs total weight pulls a 8.5% grade easily at 60mph and didn't overheat in the summer months.
Fuel mileage is around 8.5 to 9mpg on the highway which I find acceptable for this much engine. Some say mileage will go up with a few more miles on it but to date it has 27000.
May look at "chipping it" down the road.
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