Turbo-Diesel.co.uk - Diesel info
 This page gives a brief description about normally aspirated diesels.

DERV Fuel
DERV (Diesel Engined Road Vehicle) fuel over the last decade has improved considerably, it burns cleaner providing lower emissions levels with lower sulphur levels, also diesel fuel no longer `freezes` in low ambient temperatures, in cold weather diesel fuel used to wax, but with modern additives this is no longer happens, in years gone by, lorry drivers would make fires under their fuel tanks to warm up and liquefy the diesel so they could start their engines. Along with cleaner diesel fuels reducing emission levels, diesel fuel has now evolved further in late 2003, with BP unveiling a new  "BP Ultimate Diesel" which they claim noticeably improves the performance when compared to using ordinary cleaner diesel, mmmm, I will have to give it a try and I will give you the verdict!!

Diesel Engines
The most common Diesel engine is the four stroke diesel, and has been around as long as the petrol engine, though very few car manufacturers before 1983 mass produced diesel engined cars for the UK market. The four stroke Diesel engines can be split into two main categories, Direct injection & Indirect Injection, a third category is now added with the new generation common rail injection. 
Direct Injection diesels
Diesel is injected directly into cylinder bore at the appropriate moment on the compression stroke, while the air is being compressed, it creates heat, at the point of diesel being injected the compressed air is hot enough to ignite the diesel fuel. Diesel has one disadvantage over petrol in the fact that it is slower to ignite than petrol and takes 0.01 seconds to ignite, this delay causes the infamous diesel `knock`. Direct injection (also known as Di) and is more efficient than indirect injection, and usually requires no preheating on cold starting but until the late 1990's the downside is that it is a quite noisy engine and unsuitable for engine sizes under 2.5 litres due to uneven slow running engine speeds on mechanical injections. Since the late1990's diesel Electronic Engine management was introduced and small capacity Direct Injection engines became available and ran very smooth even by indirect injection engine standards and also ran quieter. Common Rail then evolved direct injection even more.
Indirect Injection diesels
Indirect injection engines have a separate combustion chamber in the cylinder head via a short passage from cylinder bores into which diesel is injected, this combustion chamber serves several purposes, it dramatically reduces engine noise (diesel knock) and significantly improves slow running with an even smooth tick over with less vibrations than its direct injection counterpart. Indirect injection engines are usually under 2.5 litre engine sizes, but its downside is that it is a less efficient than a Di engine. Indirect engines requires a pre heating system for cold starting. Pre heating is achieved by timer controlled Glow Plugs in the combustion chamber by warming the air as its being compressed to aid a cold start as the compressed air cannot get as hot as the Di in the indirect injections combustion chamber.
Common Rail Direct Electronic Fuel Injection.
Most major car manufacturers have been mass producing diesel cars / car derived vans since around 1983, now in the new millennium, Common Rail injection engines are the latest in Diesel technology, they are the dogs dangly bits in the world of diesels, getting quieter and quieter, smoother and more efficient with vastly improved performance and torque. The fuel is electronically injected in stages thus giving smoother combustion, This also means that electronic Direct injection engines can run a lot quieter than its mechanical direct injection counterpart. A high pressure fuel pump feeds a row of electronic injectors via shared fuel line from the pump,