Ram Eco-Diesel vs F150 2.7 TT - Davis Dam

NinerBikes wrote:
I've trailered with gas and with diesel. Diesel should see about 30% more mpg, under equal conditions. Part of it is that diesel fuel is about 129,000 ,BTU's per gallon, and gas is 110,000 BTU's per gallon. The other is that due to the nature of the way the fuel burns, in diesel, versus explodes at ignition with a single ignition time with gas, the efficiency goes to diesel when running on any type of otto cycle powered engine. Diesel injectors now have multiple fuel injections /ignition points, as the fuel is injected and burned at various portions of the cylinder stroke, to accomodate the way the diesel fuel burns.

Gas is 43.90 HP/hr per gallon, Diesel is 50.87 HP/hr per gallon.

Diesel engines run at about 60% to 66% of the rpms that gas motors run at, making equal torque, so since the motor is spinning slower, there are also less parasitic losses of energy to the motor, and the transmission also.

The level of torque generated by a diesel is another factor in it's favor, at lower rpms, made possible by the pumping efficiencies of a turbo charger.

Cumulatively, that adds up to about 30%.

So if this high rpm theory was accurate, small Honda's wouldn't have been the paradigm of efficiency for 2 decades. As well, the ED and EB (3.5 anyhow) will run pretty much the same rpm, until the 240hp limit of the ED is reached, at which point, the EB will be on it's way to 360 hp.....
I think you have the benefits of turbocharging and direct injection confused with diesel benefits. Quite simply diesels main advantage is higher energy content, and no throttle. Beyond that, its all trade-offs based on design, some favor diesels, some gas. But it is trading one characteristic for another......that's it.
Either way 30% efficiency is not even close to reality, but that will become apparent when 2015 mileage numbers are released. Hard to compare with such disparate power ratings. An average of both torque and hp ratings might be a realistic way to compare?