Efficiency

[Advantage Take]

Hi, this might be an already anserwed question, but I've have heard that a diesel engine runs most efficient when the egt is close to 600. For example I have been told by some big rig guys that they try to keep under 600 and under 5 lbs of boost to keep mpg up. Is there truth to this?



Thanks,

Michael

 

[TSpecht]

I have found that to be mostly accurate with my truck. I don't think there's anything inherently magical about the numbers 600° and 5psig, but rather simply because it's an indication the engine isn't working very hard. The harder you're working it, the higher the EGT and boost pressure will be, and the lower your fuel economy will be.

 

[TAbbott]

Hi, this might be an already anserwed question, but I've have heard that a diesel engine runs most efficient when the egt is close to 600. For example I have been told by some big rig guys that they try to keep under 600 and under 5 lbs of boost to keep mpg up. Is there truth to this?



Thanks,

Michael

I'm trying to imagine how slow you'd have to travel in a big rig to run it at 5 psi or less. 10psi won't hardly pull a van trailer on flat ground at 65 mph running light. Any sort of little grade or head-wind or cross-wind will get you to nearly 20 psi. Loaded heavy at all, my big truck will hit 35 psi or better on cruise on an overpass at 1400 rpm with otherwise flat and windless conditions. If you made a concious effort to maintain 15 psi or less (about what an old 335 Cummins would make) you'd be shifting gears like crazy to try and maintain any kind of road-speed grossed-out at 80,000#.