Compression Ignition Addict
Join Date: Feb 2009
Location: Nacogdoches, TX
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Diesel has almost THREE more megajoules per litre. That's a lot.
Diesels operate differently than gas motors.
Gasoline motors compress a air/gas mixture. The mix limits how much you can compress the air. Usually 9:1 compression.
Diesels compress ONLY air. Allowing for a much higher ratio. Somewhere around 18:1. That's double the air. Air allows for a more complete burn. Take a fire on the ground. You feel air getting sucked into it because it is using up air to burn the fuel, so other air must replace it. However, you still get smoke and other signs of incomplete combustion. Now, take a forced air forge. You pump air into it at the correct ratio, and it will burn VERY VERY hot with no visible smoke. Basic principle of combustion, no matter the application.
Couple the large amounts of air with the higher energy density of diesel, and that's the basic reason diesel motors are so much more powerful that gasoline motors.
Granted, they are heavier because of the high pressures inside them. So without working them hard, they don't get good mileage just because of the bulk of them. But if you load them up, they will not have a significant MPG drop as gas motors do.
As for the truck, you can buy a one ton, in either gas or diesel. The truck is the same. But the motor is what gives you such an advantage (or disadvantage) pulling anything.
2000 F-350 Lariat Super Duty, Dually, CCLB, 7.3L
330,000 + miles