I grew up on a farm, and all my life my father has been bashing gasoline engines and lauding diesels. He wouldn’t buy any vehicle that wasn’t a diesel, and we had two 1,500 gallon diesel tanks around by the barns–one for on-road vehicles and one for the tractors. As a result, I grew up plugging the diesel suburban into an extension cord in the winter, and waiting to start the car until the glowplugs–whatever the hell they were–warmed up the engine. Meanwhile, in their gasoline vehicles, my friends could fill up at any gas station and accelerate from 0-60 in something significantly less than the 30 seconds it took in the suburban. I wrote off my father’s opinion as old-fashioned, ultra-conservative, non-progressive, and wrote off our diesel vehicles as too loud, too much work, and too slow.

I’m home now, back around my dad, and back into the diesel debate.

Never in a million years would I have guessed that one day I would know how to sail (?), that I would own a sailboat (!?) and that the sailboat happens to CONTAIN A DIESEL ENGINE (!?!). And never ever ever would I have guessed that one day I would agree with my father about the benefits of diesel engines. Don’t be mistaken: I have done my own research and come to my very own, independent conclusions. They just happen to be the same conclusions as my dad’s.

This being the holidays, time for family reconciliation, good will, etc etc, I am hereby rising above my stubborn mindset for the past three decades to admit that my father was right: diesel engines are more efficient and longer lasting than gasoline engines.

Most people don’t understand the difference between diesel and gas–that was my problem. As a result of this ignorance, nearly all americans drive less efficient, less reliable, shorter-lived vehicles while all of the countries in the rest of the world drive way more diesel vehicles than us.

These are the facts: diesel fuel has more energy per gallon than gasoline, and diesel engine are more efficient at extracting that energy than gasoline engines. As a result, diesel engines get 20-40% better fuel economy and emit 10-20% less greenhouse gas than gasoline engines¹. Moreover, the nature of burning diesel requires diesel engines to be more robust than gasoline, and as a result they last much longer on average than gasoline engines.

I’ll lay some details of the mechanics: the difference between the engines is in how the fuel is ignited. In a gas engine, a spark plug actually lights the gas on fire at a particular point of the compression. In a diesel engine, just the force and heat of the compression of the piston ignites the diesel; a diesel engine doesn’t need/use spark plugs.

In the engine cylinder, diesel fuel burns whereas gasoline explodes. Diesel fuel burns steadily as it expands in the cylinder and turns the drive shaft; gasoline explodes for a short duration as it gives the drive shaft a jerk. As a result, gasoline engines have rapid acceleration, but low torque. With the slow burn, diesel engines pull like a horse, but they won’t leap out of the starting gate.

In order to ignite the diesel via sheer compression, the engine must have a higher compression pressure than a gas engine. Consequently, the engine itself must be stronger and more durable than a gas engine. It is because of this beefier construction, and the fact that the diesel burns steadily rather than explosively, that diesel engines last so long.

Diesel engines have come a long, long way technologically in the past few decades, particularly in one area: cleanliness. Environmentalists could not advocate the diesels of 30 years ago because the exhaust was too dirty. Even though they emit less carbon dioxide than gasoline engines (always have), they used to be so dirty that it offset the carbon dioxide advantage. Modern diesel engines use an array of technology to be more clean, and in the process became even more fuel efficient.

Today’s diesel engines represent an immediate, proven way to reduce america’s wastefulness and impact on the environment. A number of studies, including from the DOE, testify to the environmental benefit of adopting diesels. They win awards, and get lots of attention. Which is one reason why we will be seeing so many diesel offerings from car makers in the next few years . . .

Enough of the proselytizing–I’m sounding like my father. How does this relate to our engine situation?

I regret to admit that our engine is very certainly old technology: 30 years old, to be precise. The old technology is both good and bad for us. It is less efficient than modern engines, and much dirtier. On the other hand, it is as simple as a diesel engine can be, which means that novices like us actually have a snowball’s chance in hell of understanding and working on it. Modern diesels are computer controlled, and have high-tech add on components, none of which I understand.

Our engine emits white smoke, which means that it isn’t burning the fuel efficiently. It needs to be addressed, which may mean a relatively simple tune-up but likely means a whole lot of work and unforeseen expense. With the help of a great diesel friend and regular phone calls to my dad, we will be tackling the engine in the upcoming months. Stay tuned for more diesel details.