How Does Ignition Work For A Mechanically Injected Diesel?

[nicholastanguma]

Since there are no spark plugs there are no distributor or points. And since the engine is mechanically injected, there's no electronic ignition. So then how does the crank get turned to make ignition?

Is there just one wire running from the key ignition to the battery to the starter?

 

[Buddha.]

Ignition is caused by the compression of the air/fuel mixture.
Is there just one wire running from the key ignition to the battery to the starter?

 

[nicholastanguma]

Ignition is caused by the compression of the air/fuel mixture.

Right, but how, exactly? The crank turns to compress air in the engine. Presumably a starter turns the crank. So is the ignition system essentially the starter, the battery, and a wire between the two?

 

[PhilipE]

The starter turns the engine over. The injection pump will have some means of shutting off fuel for an off position. To give you an answer with any accuracy we would need to type of injection pump used.

On my 6BT Cummins the injection pump has an electric solenoid to control fuel flow to the engine. There is also a manual kill lever on the side of the injection pump.

 

[Buddha.]

Right, but how, exactly? The crank turns to compress air in the engine. Presumably a starter turns the crank. So is the ignition system essentially the starter, the battery, and a wire between the two?

There is no ignition system. The mixture is ignited by the heat of compression. The arrival of the fuel is carefully timed and delivered by the injector pump.

 

[1stDeuce]

^ that's the best answer.

Only spark-ignition engines have an "ignition system", which consists of the electronics that fires the spark plugs. Diesel engines are considered "compression ignition", which means compression of the air in the cylinder makes it hot enough to light off the diesel fuel as it is sprayed in by the injection pump. No typical "ignition system" required. Just as on a gas engine, the starter does get it spinning, but that doesn't make it an "ignition system". It's still a starter.

I should add that to aid cold starting, some diesels do had a glow plug system that provides a hot spot to light the mixture easier, but it's not timed at all, just hot all the time while it's active.

 

[Ozrockrat]

Right, but how, exactly? The crank turns to compress air in the engine. Presumably a starter turns the crank. So is the ignition system essentially the starter, the battery, and a wire between the two?

Not really. You need no electricity to run a diesel. Some had air starter (compressed air turned the starter motor) others had what was called a pilot or pony motor that turned the engine over.

But generally a mechanical injected diesel will have 2 electrical components. The starter system just to turn the motor. The other thing is a solenoid to stop the flow of diesel energized when the key is on and then when you turn the key off it closes and stops the flow of diesel to the injection pump. Some older diesels had a pull cable to shutoff the flow of diesel and shutdown the motor.

 

[nicholastanguma]

Thanks so much for your help in learnin me some schoolin, all ya'lls. I think I understand it now.

I have this weird fetish for mechanical technology, even sometimes bordering on motorhead obsession. No, I'm not a luddite anywhere else in my life technologically speaking, and no, I don't think I need to prepare for an EMP from the Chinese or aliens from outer space or our own gub'ment.

I just like the "authenticity" of mechanical tech. All of my motorcycles are carbureted and kickstart-only, using magnetos in place of batteries, and I've been looking for equivalent automotive systems to sort of complete the theme. Laugh at me: this started when I began looking at the electronic ignition on my carbed Jeep engine and thinking, "Hmmm, how can I get rid of the electronic ignition and become as simple as a diesel..."

I really, really, really wish I had more reason to believe that diesel fuel will still be available for passenger vehicle use twenty or thirty years from now; I'm totally confident that I can still be riding the same petrol engine motorcycles then that I have today. But, sigh, it seems VW's diesel scandals of late have given governments from South Korea to France to the USA more reason than ever to simply legislate consumer diesel out of existence.

But I'm hoping it won't happen. I've got a real itch to put a VW 1.9 MTDi into an old Ford hot rod. unk03:

 

[KarstenP]

If you don't get any diesel fuel anymore, use veggie oil. Works with only little modifications (i.e. larger diameter fuel lines and a fuel heater for cold weather applications).

 

[Zeiderman]

The day diesel is legislated out is the day you will see no more tractors, heavy trucks, trains, heavy equipment, large generators etc. When looking at what diesel runs it truly does make the world go round. And if you're looking at diesels go old, for the most part todays diesels are a far car from the days of old. While they still mechanical premise for running they are very much loaded down with electronics and emissions that are a PIA. DPF/DEF started around 06-07, so your looking at at least 10 years old. Though taken care they will last a very long time. We just did a Cummins that lost a main bearing after a million miles, got to it before it slung a rod, that's a pretty good run right there.

If you want to witness and kind of build how a diesel runs under the basic premise, Google DIY air piston fire starter.
*Not responsible for lost fingers or what not.

Sent from my SM-T230NU using Tapatalk

 

[Silverado08]

Thanks so much for your help in learnin me some schoolin, all ya'lls. I think I understand it now.

I have this weird fetish for mechanical technology, even sometimes bordering on motorhead obsession. No, I'm not a luddite anywhere else in my life technologically speaking, and no, I don't think I need to prepare for an EMP from the Chinese or aliens from outer space or our own gub'ment.

I just like the "authenticity" of mechanical tech. All of my motorcycles are carbureted and kickstart-only, using magnetos in place of batteries, and I've been looking for equivalent automotive systems to sort of complete the theme. Laugh at me: this started when I began looking at the electronic ignition on my carbed Jeep engine and thinking, "Hmmm, how can I get rid of the electronic ignition and become as simple as a diesel..."

I really, really, really wish I had more reason to believe that diesel fuel will still be available for passenger vehicle use twenty or thirty years from now; I'm totally confident that I can still be riding the same petrol engine motorcycles then that I have today. But, sigh, it seems VW's diesel scandals of late have given governments from South Korea to France to the USA more reason than ever to simply legislate consumer diesel out of existence.

But I'm hoping it won't happen. I've got a real itch to put a VW 1.9 MTDi into an old Ford hot rod. unk03:

Not to worry,Im sure diesel will be with us long time yet..although EVs will become majority eventualy,imho..

Fetish for things mechanical huh.,heres a beaut
www.coatesengine.com


Or how about an engine that improves thermodynamic efficiency by preheating incoming air fuel mixture using usualy wasted radiator and exhaust heat,,I suspect the secret lies in ceramic coatings of the pistons and combustion chambers in that one..

http://www.hotrod.com/how-to/engine/hrdp-1009-what-ever-happened-to-smokeys-hot-vapor-engine/

 

[Coachgeo]

wellll........ not sure....... Bigger vehicles that operate of high torque diesel engines may go away quicker than you think when the industry realizes (and it is starting to already) that this is the place that Eletric Motors shine the most. Though IMHO these rigs will end up like locomotives.. AKA Electric motors drive the wheels but some form of oil derivative will produce the electric power via a generator.

There is one country now running their big rigs like trolly cars with overhead lines. Not sure how many miles they have wired yet... but they are in use now. Bet their power station for those lines are diesel generators though.