Knowledge Of Diesel Engine...

[SOUTHERN SMOKE]

well as usual im bored at work, and lately i have noticed we have had a lot of new members join who are not only interested in the cummins engine but diesel engines in general, and hence nothing to do, i would like to share a little diesel knowledge with some of my friends and family on the forum, basically to help some new members out....

as many of you may know, there are many different types of diesel engines out today, i would like to go through a few and share some knowledge on all types, and maybe some of my information will help many of you out...

we will start with how diesel engines work.

A diesel engines internal combustion chamber differs from that of a gasoline engine because it is not powered by what we like to refer to as an otto cycle, instead using a higher compression of air to ignite the fuel rather than using a spark (spark plug)

In a diesel engine only air is introduced into the combustion chamber, at which time the air is compressed with a compression ratio typically between 15 and 22 resulting in a 40 bar or about 600psi of compression compared to a typical 14 bar or about 200 psi typically used in a gasoline engine.

This high compression ration can heat air to roughly 550*C or 1000*F, at or about this moment being determined by the timing of the fuel injection system, fuel is injectly directed into the compressed air in the combustion chamber. this can commonly be into a void on top of the piston, or a pre-chamber depending upon the design of the engine. thus the fuel injector breaks the spray pattern down, so that to ensure the fuel is delivered evenly.

The heat from the compressed air vaporizes fuel from the surface of the spray pattern, at which point the the vapors are ignited by the heat from the compressed air, and will continue to vaporize from the surface and burn the fuel until it is completely atomized and burnt.

At this point you get what some call the knock of a diesel engine, this is from the vaporization causing a slight delay during ignition, in return the ignition temperatures, cause an abrupt increase in pressure above the piston.

When this is achieved, the rapid expansion of combustion gases drives the piston downwards, supplying power the the crankshaft.

Diesel engines have several advantages over other internal combustion engines.

They burn less fuel than a gasoline engine performing the same work, due to the engine's high efficiency and diesel fuel's higher energy density than gasoline.

They have no high-tension electrical ignition system to attend to, resulting in high reliability and easy adaptation to damp environments.

They can deliver much more of their rated power on a continuous basis than a gasoline engine.

The life of a diesel engine is generally about twice as long as that of a gasoline engine due to the increased strength of parts used, also because diesel fuel has better lubrication properties than gasoline.

Diesel fuel is considered safer than gasoline in many applications. Although diesel fuel will burn in open air using a wick, it will not explode and does not release a large amount of flammable vapour.

For any given partial load the fuel efficiency (kg burned per kWh produced) of a diesel engine remains nearly constant, as opposed to gasoline and turbine engines which use proportionally more fuel with partial power outputs.

They generate less waste heat (btu) in cooling and exhaust.

With a diesel, boost pressure is essentially unlimited.

The carbon monoxide content of the exhaust is minimal, therefore diesel engines are used in underground mines.

Most present day diesel engines make use of a camshaft, rotating at half crankshaft speed, lifted mechanical single plunger high pressure fuel pump driven by the engine crankshaft.

For each cylinder, its plunger measures the amount of fuel and determines the timing of each injection.

These engines use injectors that are basically very precise spring-loaded valves that open and close at a specific fuel pressure.

For each cylinder a plunger pump is connected with an injector with a high pressure fuel line. Fuel volume for each single combustion is controlled by a slanted groove in the plunger which rotates only a few degrees releasing the pressure and is controlled by a mechanical governor, consisting of weights rotating at engine speed constrained by springs and a lever.

The injectors are held open by the fuel pressure. On high speed engines the plunger pumps are together in one unit.

Each fuel line should have the same length to obtain the same pressure delay.

INDIRECT INJECTION

An indirect injection diesel engine delivers fuel into a chamber off the combustion chamber, called a prechamber or ante-chamber, where combustion begins and then spreads into the main combustion chamber, assisted by turbulence created in the chamber.

This system allows for a smoother, quieter running engine, and because combustion is assisted by turbulence, injector pressures can be lower, about 100 bar using a single orifice tapered jet injector .

Mechanical injection systems allowed high-speed running suitable for road vehicles (typically up to speeds of around 4,000 rpm).

The prechamber had the disadvantage of increasing heat loss to the engine's cooling system, and restricting the combustion burn, which reduced the efficiency by 5%–10%.

Indirect injection engines were used in small-capacity, high-speed diesel engines in automotive, marine and construction uses, until direct injection technology advanced.

Indirect injection engines are cheaper to build and it is easier to produce smooth, quiet-running vehicles with a simple mechanical system.

In road-going vehicles most prefer the greater efficiency and better controlled emission levels of direct injection.

DIRECT INJECTION

Modern diesel engines make use of one of the following direct injection methods:

Direct injection injectors are mounted in the top of the combustion chamber. The problem with these vehicles was the harsh noise that they made.

Fuel consumption was about 15 to 20 percent lower than indirect injection diesels, which for some buyers was enough to compensate for the extra noise.

This type of engine was transformed by electronic control of the injection pump.

The injection pressure was still only around 300 bar (4350 psi), but the injection timing, fuel quantity, EGR and turbo boost were all electronically controlled.

This gave more precise control of these parameters which made refinement more acceptable and emissions lower.

UNIT DIRECT INJECTION

Unit direct injection also injects fuel directly into the cylinder of the engine.

In this system the injector and the pump are combined into one unit positioned over each cylinder controlled by the camshaft.

Each cylinder has its own unit eliminating the high pressure fuel lines, achieving a more consistent injection.

This type of injection system, also developed by Bosch, is used by Volkswagen AG and by Mercedes Benz and most major diesel engine manufacturers in large commercial engines.

With recent advancements, the pump pressure has been raised to 2,050 bar (30127 psi), allowing injection parameters similar to common rail systems.

COMMON RAIL DIRECT INJECTION

In common rail systems, the separate pulsing high pressure fuel line to each cylinder injector is also eliminated.

Instead, a high-pressure pump pressurises fuel at up to 2,000 bar (30000 psi), in a common rail.

The common rail is a tube that supplies each computer-controlled injector containing a precision-machined nozzle and a plunger driven by a solenoid or piezoelectric actuator.

so if anyone has any question about diesel engine, i hope this helps...

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CLICK---> GEORGIA CUMMINS CREW

"There are no stupid questions, just stupid people."

Originally Posted by milldog

Unless she makes the move first then show her the sambo stick!!!

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Last edited by SOUTHERN SMOKE : 02-25-2009 at 05:25 AM.

[chilpepr86]

Come up to maine maritime academy. We get to work on 10,000 hp all the way up to 500,000 hp ship diesel engines. Sounds like it would be right up your alley.

[SOUTHERN SMOKE]

Originally Posted by chilpepr86

Come up to maine maritime academy. We get to work on 10,000 hp all the way up to 500,000 hp ship diesel engines. Sounds like it would be right up your alley.

would love too, but im in a special field of law enforecement that i love very much and pays good, diesel is my side hobby....

__________________
CLICK---> GEORGIA CUMMINS CREW

"There are no stupid questions, just stupid people."

Originally Posted by milldog

Unless she makes the move first then show her the sambo stick!!!

[Diesel_Nuts]

Great Write up Smokey, and I am sure this will help out alot of members, and give them a better understanding of Diesel Engines. I enjoyed reading it, and learned a little something msyself.

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07 2500 Ostrich QC (E B P) 4x4, 5.9L, HTS, 8" Rize on 37s, Amsoil w/ BMK-11, Gauges, SMARTY, AEM B.F., BD Manifold, 5" MBRP, CFM+, FTE Rail Cap, WICKED CP3, Airdog, Mag Hytec's....Hard Parts Waiting to go in!!!!

[KILO]

Originally Posted by chilpepr86

Come up to maine maritime academy. We get to work on 10,000 hp all the way up to 500,000 hp ship diesel engines. Sounds like it would be right up your alley.

I think I could fit a 500k hp engine in my truck... just gotta notch the frame a little

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'07.5 2500 6.7L, G56, 4X4, 37x12.5R17 Goodyear MT/R's, airaid intake, Airgog 150, xrt 175, 5in tbe, egr delete, SB 3250 and Amsoil. Thanks for all the goodies Wally
'09 Jetta TDI for sale, 43MPG @ 80MPH on the highway

[SOUTHERN SMOKE]

bump for some knowledge...

__________________
CLICK---> GEORGIA CUMMINS CREW

"There are no stupid questions, just stupid people."

Originally Posted by milldog

Unless she makes the move first then show her the sambo stick!!!

[bh10]

Little bored Nice write up

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06 2500 4x4, White, SLT, 6speed, 552hp/ 1052tq...old numbers with stock turbo ..Now...Super B/ s475 twins-SOLD
95- 12v with some goodies

[Taquache]

Good write up, I wrote a paper in college about the advantagews od diesel over gasoline.

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2007 FIAT 5.9L 2WD QC SB ELECTRIC BLUE Leather, Heated Seats, Sun Roof w/1st Republic of Texas Flag cover,BULLY DOG TRIPLE DOG Tinted Tailights {REMOVED: Intake Baffle, Silencer Ring, Badges, Kitty} <INSTALLED: Glass Pack, ICEBOX, 2" Drop Shackles, CFM+, custom stock grill, Dipricols, 6" Tip, GHD, Fiat Badging, AIR HORNS, custom interior, eyelids> 1/4: 15.2 @ 93.4 10-3-09 powered by Smarty
'80 Chevy Short Wide needs motor and trans. I'm long as an ant and tall as a snake

[SOUTHERN SMOKE]

Originally Posted by bh10

Little bored Nice write up

yep, thats all, just a little bored...

__________________
CLICK---> GEORGIA CUMMINS CREW

"There are no stupid questions, just stupid people."

Originally Posted by milldog

Unless she makes the move first then show her the sambo stick!!!

[MegaBlueTX]

Thanks for the info.

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'06 Mega 4WD, AFE Mega Cannon, 5" MagnaFlow, Bully Dog, custom built tranny

[xdac]

Thanks for the info

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04.5 2500
Kore ● Edge J/A ● AEM Intake ● H2's on 315's ● 5' Dual Exhaust

[Megadeth]

Nice informative post!

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07 5.9 G56 with a few goodies.