why do large vechiles such as lorries use diesel engines?

Question

is it because diesel engines are more powerful than unleaded?

Answer 1

Predominantly diesel engines are more powerfull as in torque not horse power and are more fuel efficient.Diesel engines also tend to be more reliable and stronger in general than petrol engines.
Plus they require less maintenance.
The power delivery from diesel engines comes at low level rev's between 1300-2200rpm.whilst a petrol engine doesn't produce as much power until 5-6000 rpm therefore the diesel engine never has to work so hard.

Answer 2

A lot of the reason is reliability and ease of maintanence. Diesel's work on a different principle to petrol engines, relying on the sheer compression of the engine to produce detonation rather than by applying a spark to ignite it.

This high compression is where the engine derives it's torque from. And yes, economy on a diesel engine is normally far better than an equivalent output petrol

By and large, diesel engines will simply last a lot longer, essential for hauliers as the longer a vehicle runs, the better it's payback.

Answer 3

If lorries had petrol engines, you'd be talking gallons per mile, rather than miles per gallon.

But that's not the only consideration. Diesel engines are far more efficient, looked at overall. Maintenance is far lower (they're far simpler and there's far less to go wrong), They're cleaner (when you compare like for like), and they last much longer. I've seen lorries that have done half a million miles, and the engines are as good as new.

Answer 4

Diesel engines produce lots of touque but have a very narrow rev band which means thay have poor accelleration. On HGV's which have the space for large gearboxs sometimes with over 15 gears this is ideal. Cars are not really suited to diesel engines because diesel engines because of the poor accelleration and diesel engines are far heavier than petrol engines. To get the equivilent performance modern diesels are turbo charged, fuel injected and have all sorts of other add ons just to give them a bit of go!! and they still chuck tonnes of soot out the back!!!

Answer 5

Diesel engines use a different style of combustion that gives a lot more torque for a low engine speed. It would have to be an enormous petrol engine to do the same work.

Answer 6

The output torque available from an equivalent displacement turbo diesel engine is easily on the order of 2X a gasoline motor. That plus the fuel efficiency that diesels deliver at those outputs make them the clear choice for heavy loads.

Answer 7

My car weighs 1.25 tons and has a 2 litre engine. It manages not more than 28mpg overall.

The trucks I drive have engines six or seven times the capacity, with 400+hp and close to 1000 lb/ft of torque and drag 44 tons of truck and load around at an average of 7.6mpg.

Do the maths.

44 tons divided by 1.25 tons = 35.2

The truck is therefore 35.2 X heavier than the car, yet only uses
approximately 4X more fuel.

Put it another way, if you had 35 cars like mine, travelling in convoy, they would use, COMBINED, about 1.25 gallons of fuel PER MILE.

To travel 7.6 miles, they would require approximately 9 times more fuel than the truck of identical weight.

That's why we create so much in the way of greenhouse gases, because there are too many cars on the road, and not enough trucks.

Answer 8

For the same engine size, a diesel engine is more powerful than it's petrol powered cousin. For the same haulage capability, a diesel engine is also more economical.

Answer 9

more torque out of diesel economy years ago 30 they used to be petrol 6 to the gallon unladen

Answer 10

Yes, diesel engines produce more Torque, which basically equates to pulling power.