I know how diesel engines differ from gasoline ones in terms

Much higher compression ratios, they dont make a vacuum hence always need turbos or superchargers, built tougher/heavier. example a cummins 3.9L 4bt (baby 6bt out of dodge diesel trucks) are 800 pounds. Compared to 550 pounds for a chevy 350. They dont have throttle bodies, theyre controlled by the amount of fuel. Idling takes minimal fuel... lots of little things are different.

>>14886774
uh, they dont have spark plugs? that is why their compression ratio is so high, the compession causes the ignition instead of using an electronic spark plug. because of this diesel (compression ignition) automobiles are almost always super and/or turbocharged. other than that they are the same. diesels are more effecient than gas engines, but pollute tons of particulate matter. as emission laws become stricter and technology improves the real world difference in economy is getting smaller

>>14886807
diesels exist NA. they do not require FI. they draw vacuum like every engine.

but yes OP in a gas engine you control speed by limiting air intake via throttle body. in a diesel there is no throttle body speed is controlled by how much fuel is injected.

>>14886814

this guy is correct

diesel fuel doesn't require a spark plug, just very high compression

so they have a relatively large stroke to compress all that diesel fuel until it sparks

>>14886814
That's really neat, thanks for the answers. Why exactly is forced induction almost always necessary though?

>>14886965
Basically to do compression ignition you need to be able to control the compression or timing, among other things, and it's a bit easier to control the compression when you have a turbo since you can just send excess out the wastegate. Maybe in the future we'll see gasoline engines using compression ignition, aka HCCI engines. Maybe...

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That Pasta is old man

>>14886774
I'm no expert on Diesels, but I'll take my stab at it.

The first step is knowing what octane is, which is the amount of pressure a a fuel can take without detonating.

Diesel engines rely solely on compression to ignite the fuel, unlike a spark plug. As a result, diesel engines tend to have higher compression ratios.

Diesel engines do not control the amount of Air supplied to the engine, only the amount of fuel. If you want to accelerate, the engine is given more fuel. If you want to idle, the engine is given a minimal amount of fuel.

Everything else is engineering around the fuel type. The components around diesel have to be more robust, as they're dealing with more force with how dense the fuel is, and how ignition occurs. More robust internals, is more weight. More Weight is a heavier rotation assembly that can't turn many RPMs.

Diesel also burns much slower than gasoline(Hence the black smoke of rolling coal, that's unburnt fuel). A longer stroke creates a more efficient burn, as it allows the fuel more time to burn on the power stroke.

Generally speaking, high revving engines, Bore to Stroke ratio are in favor of the bore. The amount of forces thrown on a high revving stroked engine are much greater than a short revving engine.

High revving engines also generally make more horsepower, but low revving strokers generally make more torque.

Remember, Horsepower is a number calculated by torque, and rpms.

Horsepower is the rate at which work is done, while torque is a measurement of force.

A culmination of these engineering principles, means that it makes since for diesels to be low revving strokers, So they're more efficient, and more reliable.

There's also a Interesting phenomenon that poorly maintained diesels engines get called runaway. Essentially if your fueling mechanism fails, or rings fail it uses your oil as fuel, and revs until it the bearings seize. Diesels are magical.

>>14886965
its not necessary, it just greatly improves power and effeciency. without it diesels are horribly anemic. early VW diesels were naturally aspirated and even today small (non automobile) diesel engines can be found NA.

>>14886965

because diesel fuel makes very little power under n/a situations. with forced induction it can take in a lot more air and then a lot more fuel to make a bigger bang and more power

>>14887001

You are on the right track. This will take a few...

First, there is no octane as distillate (diesel) is rated in cetane which is a rating of how quickly the combustion event takes place and at how low of a temperature the event takes place. It burns no slower and the flame front is faster than petrol.

The diesel principle is an internal combustion engine that can generate 260 degrees centigrade or higher with compression alone where a precise quantity of diesel fuel will be injected at a specific timing in relation to the crankshaft. The injected diesel fuel ignites immediately as the combustion chamber temperature has reached or is over the auto-ignition point of the diesel fuel with the resulting expansion of gasses generating torque. Compression ratios of typical Indirect injecting diesels will be around 22:1, 16-20:1 for direct injecting diesels and 16:1 with Common Rail injection.

Older diesel units made use of a jerk pump. This is an in-line style pump where a camshaft timed with relation to the crankshaft actuates one plunger pump per injector. The plunger pressurises the fuel to high pressure in the injector lines. Inside the injector mounted in the head itself is a pintle and seat with a pressure sensitive spring mechanism. When the pressure in the lines reaches the 'cracking pressure' of the injector the pintle is lifted from the seat and high pressure diesel fuel passes through the seat, through the atomiser in the injector tip and into the combustion chamber with Direct Injection or into a swirl chamber in the cylinder heat before flowing down onto the piston in Indirect Injection. The line pressure drops and the pintle closes until the line pressure is raised again at the next ignition event.

Also common is a rotary injector pump where a single pumping element pressurises diesel into a distributing mechanism which then directs high pressure diesel fuel to the injector lines in a rotating sequence. More modern is the Common Rail injection where as the name suggests a single fuel rail is pressurised to a very high pressure. Each injector then has a connecting line to the common rail. The injectors are timed electronically by use of either a piezo mechanism, electronic solenoid or electronically controlled hydraulic signal. The injector is still a pintle and seat device. Common injector rail pressures are 2000-4000 Psi for Indirect injection, 4000-10,000 for direct injection and up to 35,000 Psi for Common Rail systems.

There is no requirement for forced induction for a four cycle diesel to run as the engine will aspirate. As another poster pointed out there is no need for a throttle body for a diesel engine to run either, as the diesel engine is throttled purely by the quantity and timing of the fuel injection. Modern diesel engines do have a throttle body that serves two purposes; to ariticially build manifold vacuum for EGR operation and to reduce engine run-on when shut down as the engine must work to build manifold vacuum without fuel injection and will shut down faster. Some old diesels even in cars may take a second or two to stop turning when shut off. There is a requirement for forced induction with two cycle diesels as the two-cycle engine does not aspirate and therefore requires pressure on the intake ports to overcome the pressure of the spent gasses when scavenging.

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>>14887001
>Runaway
When Petrol engines die they die.
But when Diesels die they sometimes let off with a roar to mark their accomplishments into the afterlife.

-In his dying moments he was the center off attention.
~God

>>14886981
No. That's not correct at all. The turbo is only there for performance. The fuel controls engine speed

Diesels respond so well to forced induction because of the controlled expansion of gas that the diesel process offers. It is very easy and safe to add more air and match this air with fuel. There is no danger of damage from a lean out as the diesel process does not increase temperature at higher lambda like the petrol process. Rich burning increases exhaust gas temperature dramatically though often the piston crown temperature is still acceptable. Timing wise there is no possibility of pre-ignition or knocking as there is no fuel in the combustion chamber until the injector adds it, though it is certainly possible to inject the diesel fuel too early and cause damage. The engine itself must be built very strongly to reliably run 22:1 compression or 16:1 and lots of additional air and this obviously leads to large sized heavy engines that don't make anywhere near the power of a similar sized petrol unit but consume far less fuel and should operate for many more hours than the petrol unit. These lines are becoming blurred with lightly built CRD units from Korea and China. It is yet to be seen how hypereutectic aluminium pistons will withstand 5,000 hours of common rail pressure.

You are very right in that diesel engines are primarily undersquare engines being that the stroke is longer than the bore is wide. This allows for efficient expansion of the combustion gasses, low piston speed which is important to longevity and of course the higher torque produced by the longer stroke.

With runaway it is often through the turbocharger that the oil is added. A failed turbocharger can open an oil gallery of high priority being the oil feed for the turbocharger straight into the inlet tract where it will be burnt uncontrollably as fuel. You must seal the air inlet tract to shut down the runaway or let it seize. The Detroit Diesel GM's had dampers above the blower for exactly that. As a quick anecdote many years ago a ferry was equipped with two GM 16V149 engines and was known to be a horribly dodgy operation. The compressor wheel nut backed off on a turbocharger until it became free, where the exhaust wheel and turbine shaft were blown straight out the exhaust! As a result oil was flowing freely into a two cycle diesel which is a recipe for destruction, and that's exactly what happened about five minutes later after 39 litres of diesel sat on 4000 rpm. What a smoke show.

>>14886807
>they dont make a vacuum hence always need turbos or superchargers,
There's plenty of NA diesels out there. It's just very easy to turbo them because their exhaust gasses are comparatively cool and you don't need some insane nickel alloys to cast the turbocharger casings like you do on gasoline vehicles. They also gain a lot more from more compression since that's what allows a deezal to operate.

>>14886898
They don't compress the diesel fuel to get it spark, the piston comes up the bore on the compression stroke and the fuel is injected just before TDC and because of the heat and pressure in the cylinder it self ignites. Otherwise there would be no control of advance and the engine would probably run backwards or not at all

>>14887001
>There's also a Interesting phenomenon that poorly maintained diesels engines get called runaway. Essentially if your fueling mechanism fails, or rings fail it uses your oil as fuel, and revs until it the bearings seize. Diesels are magical.
I know about this. I don't understand why people don't have some sort of emergency air supply plug to choke out the runaway engine.

>>14887131
You can carry a bit of plywood in your truck to put iver the front of the turbo to shut it down, but normally by the time it's running away the engines fucked anyway so they don't really need to build a failsafe into it

>>14887092
>>14887094
>>14887100
>>14887101
>>14887104
You seem to be a diesel mechanic. :p

Love the nights on /o/ when I actually learn something.

Some good discussion in this thread.

Iit's worth noting the fundamental reason why diesel is used for compression-ignition engines.
It's because of knock, or rather the lack of it.

Petrol will also autoignite under compression, but because the fuel is lighter and more viscous, the flame front and pressure wave travels much faster. Petrol literally explodes under compression, rather than a controlled burn. This wastes the energy of the fuel as all of the pressure rise is at the beginning of the stroke (or maybe even when the piston is still moving up the cylinder, before the power stroke); also, the pressure wave destroys the thermal boundary layer at the cylinder wall, leading to mush higher heat transfer. The knock limit means the compression ratio of petrol engines is limited to around 12:1.

Diesel, on the other hand, does not exhibit knock when it autoignites, but rather has a nice, slow, controlled pressure rise. This means that the compression ratio can be much higher that a petrol engine (perhaps even up to 25:1), which is one reason the diesel is more efficient. Higher compression = higher efficiency, always (or almost always, anyway).

All of the mechanical differences between SI and CI engines (heavier build, emissions, rev limit) come as a result of the different combustion process.

The other reason diesels are more efficient, as discussed, is the lack of a throttle plate. Only the fuel is metered to control power output, and as a result diesels run very lean and the AFR varies at different loads, unlike petrol engines where AFR should always be stoichiometric.

Bumping this thread because excellent smartboy content

>>14887094

>There is a requirement for forced induction with two cycle diesels as the two-cycle engine does not aspirate and therefore requires pressure on the intake ports to overcome the pressure of the spent gasses when scavenging.

Ah hah, ok I thought all diesels needed them, im only familiar with industrial 2 strokes.

>>14886807

>they don't make vacuum

How do the millions of N/A diesels all over the world run?

>>14887101
diesels being undersquare/long stroke for torque is a myth.
diesels built on the same block architecture as petrol relatives are usually more undersquare because smaller bore cylinder walls can be stronger to handle the higher peak cylinder pressure, and a longer stroke crank is added to get the engine back up to the usually required round number for displacement.
The blocks are made taller to accept a taller piston and the longer rod neccessary to soften the effect of the longer stroke and heavier piston.

Why do diesels make more power?

is it because the way the fuel ignites? I was told it ignites unevenly, and gradually.

Engine calibration engineer for caterpillar
ask me anything

>>14888011

It is no myth at all. I stand by my previous post and reassert that the undersquare configuration results in efficient expansion of the combustion gasses and higher torque delivery across the usable range than an oversquare configuration. Not mentioned as well is the reduction of time spent at TDC and BDC with an undersquare design versus an oversquare design. Mechanical damage to the crankshaft and bearing shells is likely when force is exerted on the piston at TDC and the less time the piston is at TDC and the less force applied to the piston at TDC, the more the longevity of the engine can be increased.

So important is the long stroke of an undersquare design and the resulting increase in torque production and decrease in time at TDC that large stationary and marine units use what is called a Crosshead connecting rod. One connecting rod links the piston to the crosshead where another links the crosshead to the crankshaft. This allows the first connecting rod to be straight up and down in the bore without any eccentricity in it's movement allowing for a very long stroke. The crosshead pivot then turns the straight vertical motion of the primary connecting rod into an eccentric motion of the secondary connecting rod to turn the crankshaft.

While you are correct in the smaller bore does naturally give a higher resistance to peak cylinder pressure the length of the stroke is not an afterthought to gain back displacement from reducing the bore. The bore diameter is usually the afterthought after the maximum usable stroke of the configuration has been designed. Where it is common in petrol engine families to increase the displacement of a similar design by adding stroke it is often the opposite in a Diesel engine family where the stroke remains the same and the bore size increases to raise the displacement.

>>14887672

The fundamental reason diesel distillate is used in the diesel process is not it's resistance to knocking. It is because of a combination of factors in that the fuel is safe to handle and pump at room temperature, that the distillate has a higher lubricating value than petrol and other vapourising fuels and the diesel combustion event is a predictable and controllable rise in cylinder pressure.

Petrol fuel is not more viscous than diesel distillate. A higher viscosity means the fluid is less able to flow, not more. As I said earlier the flame front is actually faster than the petrol flame front. Compression ratio wise there are many petrol engines operating at 14:1. You cannot put a blanket statement saying that the limit of effective compression for petrol applications is 12:1 when this is not the case.

Higher compression does not equal higher efficiency in the slightest. In fact, you have increased the energy requirement exponentially by raising the static compression ratio as the engine must now work harder over the same time period to compress the gas in the combustion chamber. This is evident in the increase in fuel efficiency in the diesel process by lowering the compression ratio. Discounting the gains made by the common rail injection system many modern diesels are seeing fuel efficiency ratings and engine speeds far higher than their ancestors now that their static compression ratio is 16:1. The benefit of the common rail system is that the engine can still very easily begin the combustion event when the diesel fuel is injected under great pressure with the lower combustion chamber pressure and temperature from the reduced static compression ratio.

With the pre-ignition point with diesel please remember that there is no fuel in the combustion chamber to pre-ignite. The fuel is not present until the injector adds the fuel. While this can be early in the cycle and cause damage it is not possible for the diesel fuel to ignite uncontrollably.

>>14887227

Glad to hear that this has been interesting for you.

>>14890095
> Mechanical damage to the crankshaft and bearing shells is likely when force is exerted on the piston at TDC and the less time the piston is at TDC and the less force applied to the piston at TDC, the more the longevity of the engine can be increased.
what the fuck mate? increased piston acceleration/deceleration is a bad thing. less time at TDC does not mean less force at TDC.
fuck off

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Didn't read such a good thread on /o/ for months.

Just to add to the previous posts, modern common rails inject diesel multiple times per stroke

Pic related, 8 injections per stroke.

>>14890368

Increase in piston speed does not necessarily equal 'a bad thing' champion. For a performance petrol engine, certainly. There are negatives such as the increased friction coefficient and increase in stress on the connecting rod and gudgeon pin and positives such as decreasing the time spent at TDC.

If you think that there are no benefits to decreasing the time at TDC, you need to go back to basics. If you think that decreasing the time at TDC is not an aim of heavy duty engine systems then I think you may need to, as you say, fuck off.

Less time at TDC does not equal less force, you are correct. It does equal less time the equivalent force has to act on the connecting rod and bearing shell at it's most vulnerable, which equals an increase in longevity of the engine. This is simple stuff mate at the low tier of knowledge that you should know before you run your mouth off.

>>14889514

They don't.

>>14886965
Because they are built to handle retarded levels of boost and compression

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>>14887943
A lot of them (including my car) have a mechanical pump in the engine that generates a vacuum.

>>14890942
That pump is there to run your brake booster and other vacuum dependent accessories, it's got nothing to do with making the engine run.

>>14891088
Yeah, I guess I misinterpreted the question as being "how do all of the vacuum-drivin components operate".

I suppose the answer to the original question would be that the intake strokes on the cylinders create enough vacuum to fill the cylinders with air, just not as much as if the intake were being restricted, as with a throttle body.

>>14890582
You were wrong and are now sperging off about something else. Which may or may not be wrong again.
I'm not going to bother reading it.

>>14891154
>intake strokes on the cylinders create enough vacuum to fill the cylinders with air,
>just not as much as if the intake were being restricted, as with a throttle body.
tell me how restricting the intake with a throttle body would allow more air into the cylinders.

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>>14891154

You are correct, the intake stroke on a four cycle diesel will cause the engine to aspirate where it will pump gas from intake to exhaust as long as the engine rotates and the valves function correctly. As there is no requirement for the diesel engine to maintain an ideal fuel:air ratio at all times there is no need to restrict the amount of air the engine can aspirate, so no throttle body is required.

There are oddball engines like the naturally aspirating version of the Nissan SD33 where a throttle body is fitted and the vacuum signal from the inlet tract is applied to the governor in order to control fuelling. This was a rudimentary way to have a dynamic load based governor setting versus the traditional cable operated governor setting. This quickly fell from favour.

The petrol engine requires the combustion of air and fuel to be as close to stoichiometric as possible, or as close to the complete combustion of all fuel and air. To achieve this we may control how much fuel is injected and when using solenoids, when the combustion event occurs using a source of spark ignition and how much air is ingested using a throttle body.

>>14891225

No, I'm very much not. Your inability to wrap your head around basic engine principles is your own issue, oh random dickhead on the interbutts.

Not acknowledging information that would counter your manufactured fallacies is a clear sign of being a total fool.

Watch the first few mins of this video

https://www.youtube.com/watch?v=OiHb2L8ei8E

>>14891286
No one gives pays this much attention to time spent at TDC.
In fact I'm sure the majority of industrial diesel engine manufactures share common stroke, bore and rod length between all their similar capacity engine families.
That rod length / stroke & bore combo being what has been used historically. Not produced to reduce time at TDC.

As for torque and pressure at TDC. Well that's up to the calibration team, not the design team.

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>>14893341

Absolute crock of shit. EMD 645 is a 567 with the same 254mm stroke, just wider bores. 710 is a 645 with an additional inch of stroke as there is no more bore material left. EMD 710 operating speed is reduced as a result.

Detroit GM 92 Series are just additional bore on the GM 71 Series.

Caterpillar C32 is a larger bore C30.

MAN 32/44 is a larger bore 28/44.

Do you honestly believe the engineers designing the engine are not aware of BMEP at TDC? And that the installation team of the majority of reciprocating diesel engines would have the manpower to lug the equipment required to ascertain BMEP at TDC on a running engine, if this equipment was not installed permanently.

Do you further honestly belive that with BMEP approaching 2.5 MPa that 'no one gives pays (the fuck?) this much attention to time spent at TDC'?

This speaks volumes about you. You may not be able to ascertain the impact of high pressure at TDC but this does not make it any less important to service life.

Just because you think it so, doesn't make it so. Your knowledge on this subject is abysmal and the assumptions you make are made on the third hand information you leech from the internet.

>>14887131
There's a video of a runaway diesel engine that cutting the fuel didn't stop it. It was sucking in crank case oil and burning that. It finally stopped when the operators stuffed enough rags into the intake to choke the engine. It must have been scary because the engine was bouncing around and it wasn't a small engine either. It stood about 7 feet tall. Single cylinder as well.

>>14891225
>You were wrong and are now sperging off about something else. Which may or may not be wrong again.
>I'm not going to bother reading it.
He is actually correct, but you just don't realise it.
More time at TDC = longer that the force is directly pushing down on the bearings. More force on bearings = less clearance = less oil that can fit. More chance of damage.
Also that there's more force on the rods.

Still best thread on the board. Bumping.

>>14893485
>More time at TDC = longer that the force is directly pushing down on the bearings.
>More force on bearings = less clearance = less oil that can fit
are you retarded too? did you learn about mechanical principles from the same place as the other drongo?
a force acting for more time doesn't mean more force you utter fucktard

>>14894746
Tell me more dude, I don't know about TDC

>>14893381
So you're a technician on a boat?

You do know what BMEP stands for right?
Because it sounds like you don't.

I calibrate marine diesel engines.
We marinise industrial diesel engines. And because we spin our engines faster, and get more power than is produced in the industrial application the core manufacturer is up our ass to validate every component for our application.

We have a huge criteria of Not To Exceed limits imposed by the core engine manufacturer.
The engine performance parameters that they are mostly concerned with are;
start of injection
end of injection
peak cylinder pressure
exhaust gas temperature
turbo shaft speed
injector tip temperature

We build and tested thermal survey engines where the rods, pistons, valve seats, crank, cylinder head, injector tips (pretty much everything) have metal slugs inserted that have a known harness to temperature relationship.

We validate all our fuel system from injector tip to lift pump inlet
We validate all the raw water system, all the turbo and air system, all the valve train, the oil system, cooling system, electronics. Fucking everything
We conduct vibration surveys of every component on the engine, measure the noise, have engines in the field (or sea) years before we go to market.
We hand build engines and measure every single component and run thousand hour endurance cycles to test for any wear to the components.
Even fucking gaskets get scrutinised in an autistic level of detail.

And not ONCE...NOT ONCE
Not in any meeting, conference call, presentation, coffee walk have I ever seen or heard anyone mention fucking cylinder pressure at TDC.

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>>14895730

No, I'm not a technician. That has not been in my job title for quite some time.

Brake Mean Effective Pressure. Different to Indicated Mean Effective Pressure as displayed above from the MAN readout. BMEP is a function of IMEP and brake torque. This is measured in real time by a propshaft dynamometer, pressure transducers in each cylinder head and thermocouples in each head and exhaust tract. And again I state with certainty that with BMEP approaching 2.5MPa, significant time is spent ensuring LPP does not occur at TDC.

I'm not phased by you marinising industrial engines. I don't often work with marinised industrial plants as, to be quite blunt, that's small vessel shit.

Your post extols your own virtues, though perhaps you should ask your superiors about the effects of the LPP occurring at TDC next time you are getting coffee for them on your walk. If you are as versed as you think you are, why can you not see that at TDC in an engine where the resulting geometry is a connecting rod linked vertically with a piston and crankshaft, and LPP occurs at TDC, that the resulting forces are transmitted vertically down the connecting rod and to a crankshaft that is not converting this force to mechanical rotation as it too is in the vertical position? And from there, why can you not see that the only support given to the connecting rod at this time is the oil film between the bearing shell and the crankshaft?

A good learning technique is to reverse the question. So let's try it out.

Why don't you explain what happens when LPP occurs at TDC, and the forces are transmitted vertically to a crankshaft that cannot convert this force to a rotational force for us. What happens here? Does a miniature version of the Stay Puft man appear between the bearing shell and the crankshaft, support the connecting rod big end until the crankshaft has rotated and the geometry allows the downwards motion of the connecting rod to be converted into rotation, then disappear only to appear for the next combustion event? Does the oil pressure rise to unmanageable levels for this fraction of a second to support the connecting rod? Use your logic, and if you don't mind, come on back and let the board know what is happening here.

Think, McFly.

Let's quantify it. The DG1 onboard is a sixteen cylinder four cycle. This means that there is a combustion event in the number one every 720 degrees of crank rotation. Therefore, at 1500 RPM, TDC occurs for 70 milliseconds if you accept TDC for one crankshaft degree. So for 70Ms all torque generated by the expansion of gas is acting on a crankshaft that cannot convert this torque to torsion. The only result from here is this force continuing to be transmitted to the oil film between the bearing shell and the crankshaft. From here, there are only two options; The oil film can support this load for 70Ms and once the crankshaft has moved ATDC the torque will be converted to torsion, or it won't be able to support this load and will displace. You should be switched on enough to figure out what happens when the oil film in the mains is displaced.

Straight from Mike Busch; “It's crucial that peak pressure occur well past TDC, because the geometry of the crankshaft and connecting rod near TDC does not permit combustion pressure to be converted into useful work (i.e., crankshaft rotation), but simply generates excessive stress on the cylinder, piston, connecting rod and crankshaft.” I'm floating in the middle of nowhere with Papua New Guinea wireless internet and even I could find that for you. I even found a pretty picture.

Again champ, thinking it so doesn't make it so. Your work experience means nothing, as does mine, if you simply repeat what you have been told and never stop to take the next logic step. Your attitude where you believe that if you have not experienced it or your bosses have not told you about it then it's not true will end up closing doors.

>>14896812
>>14896821
>>14896807
lmao idiot grease monkey

>>14896865

Poor bait, try again.

>>14897017
>bait
No, I just wanted to call you what you are.

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>>14897093

I've been called many things in a few different languages, and that's pretty shit. A barb from a teenager on a Czechoslovakian potata folding board that couldn't use a grease gun don't mean a thing.

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Bampin' with damaged deezal. This one got hot! Check out the cooling gallery on the bottom left. Little Nissan forklift engine.

>>14898805

Damnit, picture turned. Bottom right now.

>>14896807
Well of course I'm not going to putting Peak pressure to be at TDC. I think this is so basic to anyone involved that it never gets mentioned.
As long as we stay below our core engine manufacturers peak pressure limit, we are much more concerned with BSFC, NOx and PM.

Peak pressure at TDC may be more of a concern in large propulsion engines, or engines with fix geometry Rods. But for the vast majority of automotive, and smaller marine applications its not as much of a big deal as you want to make it.

>>14899932

LPP at TDC is a big drama for any reciprocating engine. I would be very surprised if your company's aim was to set up an engine in this manner, though this does not change the fact that it can and will happen. All that is required is the uncontrollable ingress of combustible fluids like lube oil or compressor wheel cleaner, in incorrect setting of the fuel pump or ECM or even a failure of a diesel atomiser. You not wanting it to happen does not prevent it from happening, much the same as you not knowing about it does not make it false.

You are correct, it should be a basic reciprocating engine principle go grasp; we don't aim to apply force to a crankshaft that is either attempting to lift the piston in the bore or is unable to turn force to rotation in the vertical position. Somehow, this is still difficult to grasp for some.

Your focus should be on Brake Specific Fuel Consumption, Oxides of nitrous and particulate matter. As a marinising agent, that's your role. The fuel consumption for the client, the output of emissions to meet targets and the reliability of the platform while adhering to supplier guidelines. You shouldn't be anywhere near this situation. But you and your company do not represent every man or woman working on a diesel engine. It happens from mistakes, it happens from lack of maintenance, it happens because the Machine Spirit decided to save up all of the shits it had planned for you for one day.

As for it being a small issue, that's ridiculous. It's just as large an issue for high performance petrol engines with nitrous or forced induction as it is for reciprocating airconditioning compressors. LPP at TDC does not make for long service life of the main bearing. I don't know why this is a point of contention for you?

If you have a spare DI engine, begin the combustion 15 BTDC at full governor setting then drop the lube oil and sample after ten hours. If Al and Pb isn't through the roof from chewing your mains I'll eat my hard hat.

poo-bum
sumtimes poo poo from bum bum
:)

>>14900083

No?! Sometimes bum bum from poo poo!

>>14890605
this. Diesels produce less power per cm2 (compensated by the massive amounts of torque).

>>14900004
point taken

Nice thread

also diesels should die out already

>>14901266
>tfw every serious piston engine north of 20l displacement built nowadays is a diesel
If the thing gets huge enough, you stop fueling it with diesel and just go straight for crude oil
Beat that

>>14887104
My friend actually had this happen while standing at a red light, the turbo shat itself and started feeding oil into the intake manifold. It was just an europoor-tier 1.9 diesel with a manuel transmission, so he managed to cut the bullshit by standing on the brakes and stalling it with the 6th gear. Apparently the engine didn't have time to do any lasting damage to itself.

File: 1360477633130.jpg (61KB, 689x522px) Image search: [Google]

61KB, 689x522px

>>14901266

It's not bad hey? There's some cool people hiding on this board. Take old mate industrial mariniser for example; he would have seen some serious shit with engines that the majority of this board could only imagine, and not just things going wrong, but the finer details of making reliable high power. If the board wasn't shitposting itself to death there'd be some cool stories floating about from people like that.

I don't believe that diesel replacement is going to happen soon unless it can be replaced by another process that consumes physical fuel for logistics purposes that delivers the reliable generation of power at acceptable temperatures with a flashpoint two or three fold higher than room temperature. The world will run on the diesel process for some time yet but I firmly believe biofuels is the next step for commercial and industrial diesel engines.

>>14901287

Not quite crude, but Heavy Fuel Oil or Residual Fuel Oil. If you are American it may be known as Bunker C. Towards the bottom of the fractional distillation tower is where these thick deposits are formed. RFO is also used in the production of bitumen for road surfaces. It must be heated to about 92 degrees centigrade to be fluid enough for handling by the fuel injection system and to remove moisture from the HFO. It is filtered by centrifuges on-board to remove nasty particulates that also settle towards the bottom of the fractional distillation tower.

>>14901404

It's pretty scary stuff! Everything is going well, chugging away then next minute, the engine is spinning up to the moon and smoke it pouring out everywhere! Good thinking by your mate to dump it in gear and stall out. Lucky he had the manual transmission.

If you get on the situation quickly like your friend did then there can often be no damage to the engine. When the engine is allowed to run away at high rpm exceeding the limit though, the damage is done in seconds.

>>14901266
Amount of diesels used in ships, trains and power generation simply prevents them from dying.

Runaway diesels are scary

>>14903966
Well i meant cars mostly. Wish people would go the petrol/lpg more in europe