why do diesel engines use spark plugs, and what would happen if you fitted a spark plug in a diesel engine?

Question

DONT why dont they use spark plugs, appologies for the typeo above

APPOLOGIES FOR PUTTING THIS QUESTION IN THE WRONG SECTION

Answer 1

They don't use spark plugs. What you think are spark plugs are heaters that preheat the cylinder to make the engine start easier.

Answer 2

Not an expert , but i know this much : Diesel engines work from the heat generated from compression , similar to a bicycle pump getting hot to ignite the mixture so there is no need for a spark plug - I hope this answers your question - i obtained this from a motor engineer -

Answer 3

t does exactly what it says on the tin - it's a plug that generates a spark. Duh. So why spend time talking about it? Well with apologies to George Orwell not all spark plugs are created equal. Some are more equal than others. They'll all do the job but the more you pay, the better the plug. All spark plugs share the same basic design and construction though.
spark plug parts

The high voltage from your vehicle's high-tension electrical system is fed into the terminal at the top of the spark plug. It travels down through the core of the plug (normally via some noise-suppression components to prevent electrical noise) and arrives at the centre electrode at the bottom where it jumps to the ground electrode creating a spark. The crush washer is designed to be crushed by tightening the spark plug down when it's screwed into the cylinder head, and as such, it helps keep the screw threads under tension to stop the spark plug from shaking loose or backing out. The insulator basically keeps the high-tension charge away from the cylinder head so that the spark plug doesn't ground before it gets a chance to generate the spark.
The type of plug I've illustrated here is known as a projected nose type plug, because the tip extends below the bottom of the spark plug itself. The other main type of spark plug has the centre electrode recessed into the plug itself and merely grounds to the collar at the bottom. The advantage of the projected nose type is that the spark is better exposed to the fuel-air mixture.
electrode typesGround electrode (ground strap) types.There are plenty of different types of grounding electrodes kicking around in spark plug designs nowadays, from 'Y' shaped electrodes (like SplitFire plugs) to grooved electrodes like you'll find on Champion plugs all the way up to triple-electrode plugs like the high-end Bosch items. They're all designed to try to get a better spark, and to that end, you'll now find all sorts of exotic materials turning up too. Titanium plugs, for example, have better electrical conductivity than brass and steel plugs, and the theory is that they'll generate a stronger, more reliable spark.
Gapping a spark plug. Gapping a spark plug is the process of ensuring the gap between the two electrodes is correct for the type of engine the plug is going to be used in. Too large a gap and the spark will be weak. Too small and the spark might jump across the gap too early. Generally speaking, the factory-set spark plug gap is just fine, but if you're running an older engine, or a highly tuned engine, then you need to pay attention to the gap. Feeler gauges are used to measure the gap, and a gapping tool is used to bend the outer electrode so that the gap is correct.
Heat ranges. Something that is often overlooked in spark plugs is their heat rating or heat range. The term "heat range" refers to the relative temperature of the tip of the spark plug when its working. The hot and cold classifications often cause confusion because a 'hot' spark plug is normally used in a 'cold' (low horsepower) engine and vice versa. The term actually refers to the thermal characteristics of the plug itself, specifically its ability to dissipate heat into the cooling system. A cold plug can get rid of heat very quickly and should be used in engines that run hot and lean. A hot plug takes longer to cool down and should be used in lower compression engines where heat needs to be retained to prevent combustion byproduct buildup.
How does the fuel-air mix happen? Magic?

You keep seeing me talk about fuel-air mix or fuel-air charge on this page, but I thought it wise to explain how this happens because it is pretty fundamental to the operation of internal combustion engines.
The fuel and air are mixed in one of two main ways. The old-school method is to use a carburettor, whilst the new-tech approach is to use fuel injectors. The basic purpose is the same though, and that is to mix the fuel and air together in proportions that keep the engine running. Too little fuel and the engine runs 'lean' which makes it run hot. Too much fuel and it runs 'rich' which conversely makes the engine run cooler. Running rich can also result in fouled up spark plugs, flooded engines and stalling, not to mention wasting fuel. Finding the right balance normally involves about 10 milligrams of petrol for each combustion stroke.

Answer 4

Actually diesel engines inject fuel into the cylinder and by using their higher compression ratio they combust the mixture of injected fuel and air.
But petrol engines have the mixture of air and fuel in their manifold and since they have lower compression ratio they need a spark to ignite the mixture.

Pay attention that petrol will automatically burns if used in the same condition as the diesel fuel is used. And this will lead to retard in the cylinder which causes knocking and noise and also the energy of the fuel will be lost.

Answer 5

The diesel will be diluted by your regular fuel. If it's not much then it won't hurt. If the vehicle runs a bit rough for a while then you'll have to live with that until the fuel is burned out. If the car won't run at all then you have too much diesel in there, that's your signal that you have to drain, but if that doesn't happen don't worry about it.

Answer 6

there not spark plugs,there glow plugs,they warm the fuel,also the air for combustion,some engines have one in the intake manifold with a fuel line going to it when its switched on it glows red hot a small amount of fuel flows on to it and vapourises then as the engine gets turnd over by th starter motor the compression is increased wich helps in starting the engine,you can call the engine a compression ignition.

Answer 7

diesel engines are ignited by compression, not spark.

gas has an octane rating (ease of combustion)
diesel fuel has a cetane rating, (difficulty of combustion)

the compression ratio in deisel engines is much higher than in gas engines. the "glow plugs" heat up the cylnders when the weather is cold, so that the engine can start.

Answer 8

Diesel engines do NOT use spark plugs....unless you are talking about cars. Those are not true diesel engines. They are hybrids if they have spark plugs.

Answer 9

Diesel is less flammable than petrol and needs to be heated up before it will ignite. The latest diesel engines pump the fuel in electronically, technically it is fly by wire as in there is no cable linkages to your engine.

Answer 10

they don't need spark plugs because they have a higher compression in the cylinder which creates enough heat on its own and sparks the fuel without the spark plug