Diesel: Noisy and slow (but not any more) internal-combustion engines

Invented by Otto Diesel, diesel engines don’t use petrol (they use oil instead), don’t have spark plugs (which means they’re more reliable and better able to cope with damp conditions), and were generally were noisy and slow until the manufacturers started spending millions on making them quiet and fast.

Modern diesels have turbochargers strapped onto them and are wrapped in lots of sound-proofing so you can’t hear them, resulting in engines that are have loads of torque (more jargon there) and are very economical. Pity the government charges so much tax on the fuel though…

Interestingly (well, we find it interesting in a geeky sort of way) diesel engines have the highest thermal efficiency of any internal-combustion engine, which is another way of saying that they convert more of the energy contained in the fuel into forward motion rather than wasting it as heat. A side-effect of this is that they take a long time to warm up, so you might regret not going for the optional seat-heaters when you buy your next car.

Diesel engines are also hard to start when cold, which is why you might have to wait a few seconds until the little “glow-plug” light goes out on the dash. This needs to be hot to enable to fuel to catch fire. The fuel also tends to turn into Rowntrees jelly in freezing conditions (although we don’t know what flavour) which is why the Scandanavians heat theirs up.

Much like a goat, diesels will eat pretty much anything and can be made to run happily on chip-fat and bio fuels. This is a contentious subject so we’ll stop there.

Diesel engines also produce virtually no carbon monoxide and last about twice as long as petrol engines.

Pretty good eh? In the UK it’s only the cost of the fuel (due to government policies that refuse to let anyone enjoy a Good Thing) that has traditionally kept the sales of diesel cars lower than their petrol counterparts, but as the price of all fuels escalates they have become extremely attractive.