Ken Macfarlane
Well-known Member
Almost the same engine, the 465's the military used based on the 478 block have fairly low brake specific fuel consumption, on paper on par with most average diesels, less than some indirect injection model and given the compromises for timing to allow multi-fuel use and low turbo boost its pretty respectable.
The agricultural motor on diesel only at first glance should do better, no dished fuel cup in the pistons, timing can be a bit more advanced, conventional injectors etc.
But instead they have a reputation as a huge fuel hog. I'm not sure this is warranted or simply the 2-135 / 2-155 are just big and heavy and can generate big drawbar hp therefore burn lots of fuel. There is nothing obvious about the engine itself that would cause it to burn an abnormal amount of fuel. At high rpm long stroke engines have higher piston speeds/friction loss but not a huge amount.
The one constant item I see referenced is huge torque reserve, this is related to the injection pump set up which is obviously different than the military motors. Huge torque reserve in my mind translates into the pump doesn't torque trim / defuel much as rpm drops.
Has anyone ever messed around with the pumps on their hercules to improve the economy while giving up some of that torque reserve?
The agricultural motor on diesel only at first glance should do better, no dished fuel cup in the pistons, timing can be a bit more advanced, conventional injectors etc.
But instead they have a reputation as a huge fuel hog. I'm not sure this is warranted or simply the 2-135 / 2-155 are just big and heavy and can generate big drawbar hp therefore burn lots of fuel. There is nothing obvious about the engine itself that would cause it to burn an abnormal amount of fuel. At high rpm long stroke engines have higher piston speeds/friction loss but not a huge amount.
The one constant item I see referenced is huge torque reserve, this is related to the injection pump set up which is obviously different than the military motors. Huge torque reserve in my mind translates into the pump doesn't torque trim / defuel much as rpm drops.
Has anyone ever messed around with the pumps on their hercules to improve the economy while giving up some of that torque reserve?