Why Are Diesel Engines Used In Semi Trucks Instead of Gas?

Question

I remember in the early 80's some car makers coming out with diesel engines in passenger cars.
Nobody liked them. My grandparents hated their diesel powered Cadillac and couldn't wait to get rid of it.
So if diesel is so lousy in cars, why is it preferred in semis and heavy duty trucks for that matter?
I understand the basics. Gas explodes and diesel burns. But what is the advantages and disadvantages?

Answer 1

Diesel is NOT lousy for cars. Blame Detroit for NOT developing diesel engines or importing nice ones. In Europe you can get a WIDE VARIETY of cars with diesel engine. Benz makes a 500 series sedan with turbodiesel... 450 HP, 650 ft/lb torque! VW have lots of diesel cars over there too. However, due to the old views of your parent's generation, diesel in the US has got a stigma that it has yet to recover from.

Why trucks have diesel engines? A few reasons: 1) better fuel economy. Diesel contains more energy per volume than gasoline. The way diesel works is compress the fuel/air mixture until it goes boom. By definition it's a high-compression engine, and with help of turbocharger (on most diesels, making it a turbo diesel) it makes plenty of hp for most needs. 2) less maintainence. To handle higher compression, diesel engines are heavier duty overall, have a lot less parts (no ignition system at all!) and less plumbing and 3) diesel engine is opposite of gas engines that it generates more torque than horsepower, which is needed to get heavy loads started.

It is true that diesels are noisier, and generates more "soot", but a) that's due to older design, and b) that's due to sulfur in the fuel. Newest engines like CAT w/ ACERT technology are extremely clean compared to engines of 5 or 10 years ago. .

EDIT: Doug B's right, diesels do have catalytic converters, but they serve somewhat different purpose than the cats for gas engines. For gas engines, the cat is used to convert unburned hydrocarbons to forms that won't get turned into acid rain and such. For diesel engines, the cat is mainly there to deal with soot and sulfur. Both cats deal with Nitric Oxides and Carbon Monoxide. So they would have slightly different formulation. Both types of cats are expensive though.

Answer 2

Gas Powered Semi Truck

Answer 3

It's pretty common but you want to fuel up at places that sell a lot of diesel fuel. Truck stops are great because you know their fuel isn't stale. Remember, 1 gallon of diesel contains 15% more energy than 1 gallon of gas. That's part of why you get better MPG. That means diesel can be up to 15% more expensive than gas and still be a better deal.

Answer 4

The Diesel has more power and last three to four times longer than gas engines. The Diesel you refer to in the 80s were not true Diesel they were a poor attempt to convert gas over to Diesel. The Diesel engines in cars now are true Diesel And will last four times longer than gas powered cars.You can also convert it to run on old corn oil,peanut oil etc. or use Bio Diesel

Answer 5

good answer kasey but fyi new diesel trucks are equiped with catylitic convertors,they are built into the muffler itself.

Answer 6

ive never seen a tractor with a gas engine, desils tend to have more hauling power than gassers, and they run forever, litterally over a million miles. i guess someone out there has a gas tractor tho, i wouldnt say no one does it. would seem like a waste of money tho.
desils suck in cars b/c they dont turn up as fast as a gas engine, so they acceletate like crap, and i dont know anybody who cares about their car and wants to pull stuff with it.

Answer 7

TORQUE!!!!!...the main reason..Need alot of it to move what they are hauling..would use alot more gasoline to pull that load...drawbacks are cost