Diesel Engines

The average americans knowledge of diesel engines is that they are loud, polluting and slow. However, diesel engine technology is quite an interesting topic. This thread will give the average joe more info then he/she would care to remember. This is not to say that members on here do not know anything about diesels, many seem to, this is just a thread to answer/clear up some questions on diesels and then some. On a side note this thread may almost sound like an ad for the Duramax at times, but i know the insides of this engine much better than other diesels so its easier for me to use it as an example.

If you have any other questions, comments or need more info or something cleared up just ask.

First a history lesson. The first functioning diesel engine was built by Rudolf Diesel in the late 1800s. It originally was designed to run on coal dust, later versions were run on peanut oil, but the basic principle applied, using combustion to create heat then injecting the fuel source to create power. Rudolf did not want to name his engine after himself but his wife insisted he did. Fast forward a few years and Rudolf is traveling on a ship with many other people of high power, when the ship arrived at its destination Rudolf was nowhere to be found. What actually happened has never been discovered but there are two theories. One is that he was thrown overboard by greedy members on the ship, the other theory is that he committed suicide. He devoted his life to his engine and was always stressed and sometimes depressed. Nevertheless his engine design would progress and later on in the 20th century it would nearly take over the world market.

So how does a diesel work??

First lets look at the fuel. Diesel is a heavy oil fuel. It has a higher energy content than other fuels used in internal combustion engines, and has good lubrication properties. Diesel fuel is not combustable when just sitting in the fuel barrel. If you hold a flame to it, it will burn but the fire will stop once you remove the flame, whereas with gasoline, one little spark and kaboom. So how does it burn then, when it is introduced into the combustion chamber it is under very high pressure and is injected in a fine mist into the very hot air created from the diesel engines high compression ratio, there is a short delay and then it combusts.

Now for the diesel engine cycle basics.

First, it should be noted that there are two types of diesel engines. 2 stroke and 4 stroke.

I will cover the two stroke engine first and the majority of the rest of this post will cover 4 strokes as that is what the average consumer deals with. Two stroke diesels have been around forever and currently are the most efficient ICE on the market with the worlds largest engine (5.6 million ft-lbs of torque) having an efficiency rating over 50% when looking at Brake Specific Fuel Consumption (BSFC). The two strokes many people remember are the old two stroke detroit diesels which were available in many applications back in the day. The typical two stroke diesel cycle is different than that of the two stroke gasoline engine. Air enters the combustion chamber through ports in the cylinder wall. It enters when the piston is a Bottom Dead Center. The air is always under pressure in two stroke diesels, which is why they all have either a supercharger, turbocharger(s) or both. Then the air is compressed, the fuel is injected, power is created and the piston travels downward. Now instead of the exhaust exiting on the other side of the cylinder like in a gasoline two stroke, there is an exhaust valve at the top of the cylinder that opens and the exhaust is pushed out by the incoming fresh air and the cycle repeats. If you have ever heard or seen one of the older two stroke detroits you will know that these engines are quite noisy and sound about like they are going to blow up. The larger marine two stroke diesels do not have these characteristics but also spin much slower, the worlds largest diesel spins 102RPM.

Now for the four stroke cycle.

Air is ingested into the cylinder through either one or two exhaust valves. However unlike a typical gasoline engine (not direct injected) there is no fuel mixed in with this air. The piston then travels upward on its compression stroke where it compresses the air much further than even a gasoline engine running on methanol would dare to go. Typical compression ratio on diesel engines ranges from 16:1-18:1 with some going as high as 25:1. This is the reason diesel have such long strokes, they need to get a lot of air in the cylinder. Once the piston reaches TDC or somewhere close, the fuel is injected through a multi-hole injector at pressures up to 32,000psi on the new diesels or as little as 3,000 in older diesels. This fine mist of diesel combusts after a short delay thus sending the piston downward. Exhaust is expelled through one or two exhaust valves.

Now for a more in depth look at different components of a diesel engine.

Lets start with hard parts (the engine internals).

And first on that list is the cylinder block. The cylinder block on diesels is much heavier and stronger than other ICE engines and it has to be to withstand the immense forces put on it. Historically all blocks have been Cast Iron however many newer ones are being made using Compacted Graphite Iron to save weight and still have the strength. These blocks come in a wide variety of shapes and sizes with many different features. Most off-road and larger on-road diesels have a wet sleeve design, meaning that there is no cylinder wall just the sleeve. There are also dry sleeves which are sleeves inserted into a machined cylinder. The reason these engines use this design is for service reasons. If a sleeve becomes pitted or a catastrophic engine failure happens, the block can still be salvaged with very little machine work required. Off road and large on road diesels last a long time. Typical over the road engines last for 1,000,000 miles. Shorter trip diesels such as UPS trucks have about half the life expectancy. UPS overhauls all of their engines in the brown box trucks at 500,000 then sends them out for another 500,000. Passenger vehicle diesels typically do not utilize sleeve designs is due to the fact that 9/10 will never see the day they need to be overhauled as consumers do not put enough miles/hours on them before the rest of the vehicle deteriorates. In addition smaller engine blocks are cheaper to produce. However sleeveless engines can still be overhauled, the cylinder walls are just "overbored" and "overbore" pistons are installed. Overboring is the process of making the cylinder bore larger to remove any imperfections. Other things you may find in some blocks, such as the Duramax, are induction hardened walls which is what creates the "leopard" spots on the walls. This makes the cylinder wall stronger and more resistant to wear. Its not uncommon for a Duramax engine to be tore down with 100,000-200,000 miles and still have the factory cross hatching visible.

The part responsible for transferring lateral motion into rotational motion in any ICE is the crankshaft. Once again diesel cranks are built tough and heavy. In other the road semi engines, cranes are used to install them. On my Duramax I have a hard time wrestling the thing myself. Diesel cranks undergo other processes as well to make them even more durable, the Duramax crank for example is forged and not machined from a billet. Then the cranks are heat treated and finally, nitrided. Stock Duramax cranks are so strong that there has been no need for an aftermarket replacement. They have stood up to over 1,500hp on numerous occasions. The only thing that kills them is bad harmonics, which are waves created by every engine while it is running and are supposed to be absorbed by the harmonic dampener.

Next lets talk connecting rods. The connecting rods on diesels have much more "beef" to them than other ICEs. And again this is due to the increased stress on them. There are two big stresses on a diesels rod, for one they are longer than many gasoline engine rods due to their long stroke. The longer an object is the more prone to failure it is when under stress unless it is built heavier to handle increased stresses. The other factor working against the rods is the high compression ratios and cylinder pressures of a diesel engine which are very high. The material of these rods differs by manicaturer but Iron is usually a main element. Many stock connecting rods are shot peened from the factory. Shot peening relieves stresses in the metal to reduce the risk of failure. The shear size and strength of these rods adds to the diesels cost. For example, a stock set of Duramax connecting rods will run you about $1,600. A performance set of connecting rods for a 350 SB Chevy will run you maybe $400, and thats a performance set. A performance set for a Duramax such as the ones i will be running in my truck (DPR X-Beams) are $2,850 for a set. Performance diesel rods are made out of the tuffest stuff out there, the DPR X-Beams are forged 4340 Billet steel. Forged Billet is the toughest you can get, and 4340 is one of the strongest metals (titanium is still stronged but $$$$). There are also many designs including X beam for the ones I will be running, H beams such as carrillos and I beams such as the stockers. In addition there are some interesting features to these rods, stock duramax rods have fractured caps to improve fitment and reduce manufacturing costs. Basically a precise hammer breaks the cap away from the rod as they are manufactured as one piece. Some Performance rods even have a hole "burned" into them to add additional lubrication to the wrist pin.

Which brings us to the pistons.

Diesel pistons are again stronger for the same reasons as everything else but have some other different features as well. Unlike many gasoline engines, the combustion champer on a diesel is only in the piston and not in the cylinder head. The combustion chamber on diesel pistons is very large and is typically a large bowl with a dome or cone in the middle. The combustion chamber design is directly related to the fuel injection system and emissions. Ceramic coating the tops of the pistons and teflon coating the walls of the pistons has become fairly common as well to increase durability. While many of these pistons are cast from iron, aluminum pistons in a diesel are not uncommon at all. Another thing that many diesels are taking advantage of is piston oil squirters which injects oil into a hole at the base of the piston which in turn cools to top of the piston. This is not new technology at all but is being implemented by more and more manufacturers.

Moving on to the cylinder head. The head on diesels is again much bulkier and stronger. Most have cast iron heads but aluminum heads are gaining popularity such as in the duramax engine and other smaller passenger vehicles. The headgaskets on diesels are also very elaborate and expensive. A set of headgaskets for a duramax are $220, whereas on a 3.4L V6 Chevy motor they are about $30 a set. In addition the clamping load thrust upon these headgaskets is immense and sends many mechanics to lunch early. I had sore arms and shoulders for a few days after the stretching sequence of the ARP head studs in my duramax.

Now onto the valvetrain. Diesels use both overhead and pushrod valvetrains it usually depends on the application. Most over the road semi engines utilize overhead camshafts which is necessary for the engine brake. Other engines such as the duramax use pushrod systems both in flat tappet styles and roller styles (used in the duramax). Like a gasoline engine, 4 stroke diesels use both two valve and four valve designs with most new diesels being 4 valves. In the center of these valves is where the fuel injector rests on direct injection diesels. Again everything is much stronger.

Next we will move onto the two parts of the equation that equal power, fuel and air.

I will start with air.

Currently, nearly all diesels over 50hp are equipped with forced induction. Forced induction is the process of compressing air and supplying it to the engine under pressure higher than that of the typical atmospheric pressure of 14.7psi. When you hear people talk about "boost" they are typically referring to forced induction. When measuring the boost and boost gauge will normally see, it is the pressure that the air is under when it is higher than atmospheric pressure. However when tuning engines, typically the ECM is programmed for the Manifold Absolute Pressue with the atmospheric pressure added to the number, a key thing to remember when tuning.

Diesels rely on forced induction so heavily because they rely on mass quantities of air to create the cylinder pressure needed to ignite diesel fuel. Lower hp diesels dont necessarily need them as much, but typically just increase the displacement. Many older diesels didnt have turbos because they did not have to meet any emissions standards.

There are two common types of forced induction and both have their own variations. Supercharging and Turbocharging with the latter being the most common and most efficient.

I will touch on supercharging just a little bit. A supercharger (otherwise known as a blower) is driven off of the engines crankshaft. The plus side of this is that it creates "boost" instanly providing instant power and no lag. However the downside to superchargers is that they are highly inefficient as they use the engines power to run them. A great example is Top Fuel Dragsters. These Nitromethane guzzling engines, create up to 8,000hp for 4 seconds and are then rebuilt, the cost is about $1,000 per second in maintnence. The huge supercharger on them takes over 500hp to run. A huge ineffciency.The most common Roots style Superchargers used in drag racing actually trace their roots back to the 2-stroke detroit diesels, since the two stroke diesels needed them to scavenge the air. Drag racers adapted them to their cars and began making power, the aftermarket kept the famed numbering system of detroit superchargers (4-71, 6-71, 14-71 etc). Currently the detroits were the only mass produced diesel that utilized a factory supercharger although others do exist, detroit was the most common.

Now for turbocharging, which is one of my favorite topics. As I stated nearly all newer diesels over 50hp have a turbo, which means theres a lot of technology out there. But first, what is a turbo, how does it work and what does it do.

A turbocharger is any component that creates forced induction using the exhaust gases as energy. Turbos are driven by the exhaust energy and thus are very efficient and really dont use much power compared to the power they can create. What they are doing is using the wasted exhaust heat to create extra intake air which allows for a more complete burn of the fuel.

While there are a lot of different ways to go about constructing a turbo and how many to use, the basic design is still quite simple. A centersection which houses the bearings and oil as well as coolant if equipped. Then there is the exhaust turbine wheel which is what the exhaust gases turn. It is friction welded to the shaft which passese through the center section to attach to the compressor wheel which has the job of compressing the air using a series of blades at precisely calculated heights and angles. Behind the compressor wheel is the compressor backing plate. All of this would be of no use without the turbine housing and compressor housing which go over the wheels and attach to the center section for the turbine housing and the compressor backing plate for the compressor housing.

Now for different technologies and other parts.

Cooling is provided to all turbos by the engine oil. Some engines even go as far as to have the turbo oil seperate from the engine oil but this is not common. The oils only job is to lubricate and cool the bearings. Nothing else on the turbo itself needs cooling. Due to the fact that oil is only supplied to the turbocharger bearings when the engine is running, many manufactures always suggest letting the turbo cool down for a minute or two after you have been running it hard. Failure to do this could result in oil coking which will restrict and sometimes even prevent oil from getting to the bearings which will cause failure very quickly, as turbos spins hundreds of thousands of RPMs. A lot of newer turbos especially marine and passenger vehicles utilize water cooling as well. The big reason for passenger vehicles using it is due to the nature of the consumer. Besides the fact that most consumers would ignore the cooldown period entirely, not having to cool down the turbo for as long is a big convenience factor. Water cooled turbos still should be cooled down when you are really working the turbo such as towing and such, but typically when your done driving just wait for the turbo to spool down and cool down a touch (idle for about 10 seconds) and then shut it down. The water cooling is obviously used in conjunction with oil cooling as water really isnt the best lubricant for bearings.

There are two bearing designs in turbochargers. The sleeve/journal and the ball bearing. In a journal bearing turbo the shaft is supported by journal bearings on both ends of it within the center housing. These bearings have holes in them so that the shaft rides on a film of oil when these bearings go out, the radial (up and down) shaft play will increase and the wheels eventually will contact their housings and self destruct the turbo. While the journal bearings allow the shaft to rotate freely, there is another force upon the shaft which is referred to as thrust or the axial load, and the bearing is (wouldnt you know it) called a thrust bearing which controls the axial load. A thrust bearing is only found on the compressor side of the turbo, behind it is a thrust washer. The thrust bearing is also lubricated. When the thrust bearing goes out axial (in and out) play increases and again the wheels contact the housings and the turbo self destructs. Turbocharger bearing tolerances are very tight, axial play on a duramax is .004" Wear on this bearing can occur when a turbo is oversped too often or when it "barks" which is what happens when the turbo goes from full speed in its normal direction, to full speed in the opposite direction and then back again. This is caused by the air in the intake manifold stopping and flowing back towards the compressor wheel which is caused by going from a large load to no load in a split second. This is much more common on gasoline engines where the air uses a throttle, it is less common on diesels. Blow off valves are used to prevent this by venting the pressure into the air when the event happens. Dual ball bearing turbos are the other design although some are hybrids. Dual ball bearing turbos do not rely on the shaft floating on a film of oil so their oil requirements are lower. They also allow quicker spoolup of the turbos increasing throttle response. The downside of these turbos is that they cost a lot to produce and are very expensive to repair, many dont even repair/rebuild them. A GT4202 (journal bearing) turbo is over $1,000 less than its ball bearing counterpart the GT4202R.

Wastegating is an age old turbocharging technology for fixed geometry turbos. Basically exhaust gases are routed around the turbine wheel to prevent overspeeding the turbo and/or prevent supplying too much pressure to the engine which in turn can be catastrophic. Wastegates come in two designs, internal and external. Internal wastegates are intergrated into the turbine housing and are typically a flapper valve. External wastegates come in a few different styles and mount before the turbine housing. Both styles are activated the same way, when boost pressure reaches a certain limit. The wastegate head is a spherical shaped piece with a spring inside of it. Once the boost pressure reaches a certain pressure the spring is compressed and it transfers the energy through the rod to the valve opening it to vent gases around the turbine wheel until pressures reach a desireable level. This technology is pretty simple and bulletproof but with new emissions standards many manufacturers are turning to other methods.

One of the most common newer technologies is Variable Geometry Turbos (VGTs). There are two different designs of this technology. One is the sleeve design (also known as the nozzle design) where a sleeve is slide in and out, controlling the flow of exhaust gases that spin the turbine wheel, the other design is the vane design where multiple vanes are used to control the flow of exhaust. Both of these designs are electronically controlled and are used due to the fact that they can precisely control the amount of air delivered to the engine to reduce emissions. These turbos also tend to noisier than fixed geometry turbos, but on the flip side tend to quite down the engine exhaust noise.

Recently another design is going into mass produced on new Ford trucks. The New Ford designed and built 6.7L V8 Powerstroke Diesel (codenamed Scorpion) utilizes a very interesting turbocharger. Gone are the twin turbos of the 6.4. The new turbo is two turbos in one. Two compressor wheels are mounted back to back on a common shaft with a plate seperating them. They are both identical wheels. The turbine side is a variable geometry vane style turbine wheel.

Whats better than one turbo? Two whats better than Two? More than two.

Multiple turbos are gaining popularity in production vehicles most noteably the 6.4L powerstroke, many over the road CAT engines and the new ISX cummins. And also some BMW diesels.

There are many ways to use multiple turbochargers.

Compound turbocharging also known as sequential or series turbocharging is one of the two most common ways to use multiple turbos as well as parallel turbocharging. Parallel turbocharging is tow identical turbos splitting the load. So on an 8 cylinder engine each turbo uses exhaust from 4 cylinders. Compound turbocharging uses two or more stages of compression although two is the most common. Compound turbos take up a lot of space due to the plumbing. On a two turbo system there is the atmosphere turbo and the high pressure turbo, with the atmosphere turbo being the larger of the turbos if one is larger than the other. Here is how they work.

Exhaust

exhaust manifold-high pressure turbine-atmosphere turbine-exhaust system

Intake Air

air intake-atmosphere compressor-high pressure turbine-intercooler(if equipped)-intake manifold

The reason compound turbos are used is driveability, emissions and power. If an engine needs 1500cfm of air at 60psi one large turbo could supply that, but a large turbo would take up a lot of space, would have tons of lag (the time before a turbo spools) which results in less throttle response and higher emissions. By using two turbos compounded, a smaller turbo can be used to provide boost quickly and eliminate lag, improving throttle response and emissions, and then the larger turbo will spool up and add the additional air needed at high RPMs. Typically on these systems the high pressure turbo is wastegated.

Both Parallel and compound systems have been used together in performance applications and in large off road engines. For example in tractor pulling its not uncommon for tractors to have 3 or 4 turbos. In 3 turbo systems there are two options, two smaller turbos (parallel) can compound air to one large turbo, or one smaller turbo can compound air to two larger turbos (parallel) on four turbo systems two compound two stage turbocharger systems are mounted in parallel.

Some compoud systems will completely divert exhaust and intake air around the high pressure turbo to allow an even smaller high pressure turbo to be used since it can be essentially switched off when it is out of its compressor map. This is not mainstream though and is to complex.

And finally, another turbo technology is the turbo-compound used by Cummins on off road engines. Basically its compound turbo setup but minus the compressor side on what would be the atmosphere turbo. Exhaust leaving the turbocharger turns another turbine wheel downstream which is connected to the flywheel and provides a slight power assist.

One most turbo charged engines an intercooler/aftercooler/CAC is present. Most production units are air to air CACs which means they function just like a radiator except instead of coolant being cooled, the air charge is being cooled. Intercoolers are mounted in between the last turbo to touch the charge air and the intake manifold.

Air-Water intercoolers are common in performance applications and are going to be in the new 6.7L Powerstroke. These units surrond the air core is a coolant. Most peformance applications simply use a water/ice bath or a plain dry ice bath, but these only work for short periods of time. Fords production design has its own coolant and the coolant has its own radiator.

There are other methods of cooling charge air as well, but most of these are for short periods of time.

Nitrous oxide is great for cooling air, if it is allowed in the event you are competing in, AFAIK its illegal on the streets. It is also risky business as it is an oxygen extended and does alter timing. Multi stage nitrous systems can provide a dramatic increase in power if enough fuel is present.

Water injection works by injecting distilled water into the intake manifold in a fine mist. Its not uncommon for tractor pullers to use 2 gallons of water in one 300' pull.

C02 foggers, these "fog" an air-air intercooler with CO2 which drastically increases the cooling effect of the CAC.

Liquid Nitrogen Baths have also been experimented with as have refrigerant intercoolers.

Now for the fuel injection side of things.

While there are many types of diesel fuel injection, one principle remains, inject diesel fuel at or near TDC to create combustion.

There are two forms of diesel injection, indirect and direct injection with the latter being the most common.

Indirect injection isnt really used anymore, but it is an interesting design. Indirect injection sprays the fuel into the prechamber at just the right time so that the fuel will swirl out of the prechamber and into the combustion chamber creating combustion. Early VW diesels and GM diesels utilized this technology. One of its advantages is that the combustion noise is relatively low which back when it was common was a big thing, but newer high pressure systems take that one step further.

Direct injection engines inject the fuel directly into the combustion chamber at or near TDC. There are many different systems of direct injection.

All fuel injectors have the same basic design of the nozzle, fuel is not shot in through one hose like a garden hose nor is it constant. The fuel actually pulses due to the deflection of the spring in the injector. The fuel exits the nozzle through multiple very small holes and thus creates a fine mist.

First ill start with how the fuel is supplied in different systems.

Inline pump systems, the pump is driven off of the crankshaft uses a camshaft inside it to actuate delivery valves which pressurize the fuel (around 4,000psi) and send it to the injector at the exact moment the injector needs it, the pressure in the line "pops" the injector mechanically. Essentially the pump is like the distributor on a gasoline engine, and it does need to be timed. These systems were very common and along with the common rail are the only system used in high performance applications due to the amount of fuel they can supply. The famed Sigma pump can supply up to 2,000cc's.

Mechanical Rotary Pump systems operate in a similar manner to inline systems but instead uses a rotary pump to pressurize the fuel and send it to the injector when needed, versus a camshaft inside the pump actuating the injectors. These pumps too need to be timed.

Electronic rotary pump systems such as the CAPS system use a rotary pump and mechanical injectors typically, but electronically control when each injector is given its fuel. These systems can be found on many cummins engines.

Camshaft actuated injectors, common on older semi truck motors, this system uses a common pump to supply constant pressure to the injectors, an extra lobe on the camshaft actuates the injectors.

HEUI (Hydraulic actuated electronically controlled unit injector) is a system used by CAT and by ford on the 7.3 and 6.0 powerstroke. It was used to reduce noise and emissions as it allowed fuel to be injected at high pressure(up to 24,000psi). It works by using a high pressure pump to pressurize the fuel, then uses high pressure oil to actuate the injector and pressurizing the fuel even more, however the injector timing and duration is controlled by the ECM.

Common Rail. This is the cream of the crop and the most common injection system of today with nearly every on road diesel engine and many off road engines using it. The common rail system is actually rather simple, yet very expensive due to close tolerances. In the common rail setup there is the CP3 which is the high pressure pump, this pump pressurizes the fuel to as much as 34,000psi enough pressure to cut through steel with water hench why the parts are built so heavily. This fuel is then fed to the fuel rails which are connected to the injectors through a seperate set of lines. The rail acts as a resevoir somewhat however serves no purpose in timing hence why it is called a common rail. A diesel common rail is similar to a gasoline common rail but built about 100 times heavier. The ECM controls injector pulse width and timing. Basically very high pressure fuel is available at every injector whenever the ECM decides to fire the injector. These injectors are very expensive and complex, however not as complex as a Piezo injector. High pressure common rail systems can be dangerous though, if you dont know what Hypodermically injected means, stay away. Basically diesel fuel can get under your skin before you know it. Not good.

Piezo injectors coupled with very fast 32-bit ECMs and ultra high pressure common rail injection systems are the wave of the future for now. Piezo injectors are very complex high priced and low tolerance components that can deliver outstanding results. These injectors can inject up to 7 times per injection event (power stroke). By spreading the fuel injection out over 7 injections versus 1 noise is kept to a minimum as are emissions and power and fuel efficiency increase. The 7 injections can all be different amounts as well if desired. The injections occur before TDC, at TDC and after TDC.


One last diesel question im sure a lot of you have. How does an Engine Brake (jake brake) work and what does it do. Below covers engine brakes/retarders and I will touch on exhaust brakes later on in this post.

First let me start by saying Jake Brake is a registered trademark or Jacobs Reynolds Engineering and if any of your towns have signs that say "no jake brakes" you need to report them att Jacobs Vehicle Systems - Home. Jake Brakes are not the only engine retarders on the market, there are other ones but the Jake was the somewhat original.

First another history lesson. Clessie Cummins was showin goff his diesel engine in the 1930s when his semi he was in ran away down a hill due to brake fade and nearly killed him and his crew. He set out to design the engine brake. The story on how Jacobs Engineering got involved is a story for another time but it is quite interesting.

An engine brake is a compression release brake.

Its operates by opening the exhaust valve at TDC which release the compression, then instantly closing it so there is no air in the cylinder, when the piston trys to travel downward it has nowhere to get air from and an immense vaccuum is created (on a 565hp Cummins ISX the engine brake can create 600hp of braking force).

Now you may be wondering how this works since there is fuel in there, which is true on older diesels but on electronically injected diesels there is something called the Deceleration Fuel Cut Off (DFCO) which means when you release the throttle to 0% no fuel is injected. The engine brake will only work if the switch is activated, throttle position is 0%, the RPMs are above idle and the clutch is engaged.

Engine Retarders have up to 3 stages on a typical inline 6 cylinder diesel. Low is 2 cylinders, Med is 4 cylinders and high is all 6.

Now you may also be wondering how these systems can alter the timing of the exhaust valve. Its actually quite simple and works somewhat like Hondas V-Tec but actually serves a purpose. There is an extra lobe on the camshaft, during normal operation this lobe actuates nothing, when the engine brake is activated the lube then takes over control of the exhaust and is actuated by an electric over hydraulic system.

There is a common misconception that engine brakes are noisy which is not the truth. On a truck with a muffler in good working condition an engine brake is only 2db louder than when the engine is accelerating. Many times truckers are using them and you dont even know. Now when a muffler isnt functioning properly or the owner has removed it, an engine brake is much louder than exhaust noise when accelerating. Thus Jacobs Reynolds Engineering has been working on getting the signs removed since they are not louder on vehicles that are legal. Trucks without mufflers are illegal. we dont post signs in town that say no-speeding, no-burnouts, etc.

Now there is also the exhaust brake typically administed in two ways.

The most common way is a butterfly valve in the exhaust which will not activate unless the throttle is at 0%, the switch is on, the engine is above idle, and the automatic transmission is in gear or the manual transmission is has the clutch engaged. The valve then restricts exhaust flow out of the motor creating a strong backpressure against the pistons and thus slowing them down, while not as effective as the compression release brake as listed above, they do work well and are easily adapted to any vehicle.

The other method of administering and exhaust brake is on engines with a VGT turbo. It works the same as above but does not have the butterfly valve, instead the turbo vanes are closed to create a restriction. This is standard on 6.7L Cummins equipped Dodge Rams.


Thats all for now, my fingers are dead. More later on emissions equipment, other interesting facts and whatever else I decide to come up with.

 

Mobil Delvac is great stuff, as is Rotella T.

However in the Duramax case, quality of motor oil/frequency of changes has not seemed to make a difference on the looks of the internal parts.

On all of our equipment at the farm we use a generic 15w40 year round (i live in wisconsin). Only on our two older tractors do we run straight 30w in the winter.

I ran this generica stuff and changed it at 5,000 miles if i remembered to, and the insides of my cylinders look like they were new. Induction hardening is not a useless process and manufacturers do use it for a reason.

Im not a person who follows the oil hype. I like a plain generic oil. The only special oil i use is in my pulling truck, but that engine will fill the oil full of soot in a matter of minutes.

The reason most americans are brainwashed into thinking that all oils are the same is that (as i stated above) most of them will not ever see the day their engine needs to be overhauled/replaced. The average consumer simply does not put enough miles on their engines to really wear them out before the rest of the vehicle wears out.

I am only speaking for diesels. Gas engine people can do what they want. I know nothing about them besides the fact that they are cheap and inefficient.

 

My comment of gas engines being inefficient was a little uncalled for and requires some more explanation from my side of view.

First ill state the Prius engine is one of the most efficient gasoline engines out there.

When i talk effciency I talk BSFC which is a measurement that is standard across the board just like BTUs. The prius II engine has an energy efficiency rating of 37% which is one of the highest if not the highest for a gasoline engine.

Diesel engines are usually over 40% with one of the highest being 54%.

Thats what I mean when I say efficient. The fact that a prius gets 50mpg and a TDI gets 40mpg is unrelated.

When I say cheap, its because they are by nature. They take less sophisticated parts with less strength and thus making the cost of production for a gasoline engine lower.

 

Rotella was simply an example of a good oil that people pay more money for than other oils.

I DID NOT say that the Duramax was hard on oil, I said that my personal Duramax was due to its modifications and what it does. Many tractor/truck pullers change their oil every couple of hooks, and the oil they use is not cheap, most run Cen-Pe-Co which is not a synthetic

Not a hybrid vs diesel comment, see the post above this one that I just made referring to what I mean by efficiency.

This has nothing to do with anything in this thread and is completely unrelated at this point. i have not covered advantages or disadvantages of diesel engines yet. Thus this post implies you are just looking for a fight or dont like diesels.

Cold weather is not always a diesels match, yet everywhere where it is very cold you will see mostly diesel engines.

There are many things that aid in a diesels cold weather starting ability including glow plugs, intake heaters and block heaters as well as Ether assist starting aids.

TDIs do not have block heaters and that is their own dumb fault.

was this directed at me?

 

What does this post mean? Its very unclear. I am not talking about emissions, I have not covered that yet.

I was stating efficiency see two posts above this one for my explanation on it.

 

very interesting.

And let me first say i didnt mean to come across wrong in my other posts, i had a little bit of rage in me so I may have come across that way.

Im familiar with waukesha and natural gas engines, as well as recovering the heat off of gensets. Ive done a lot of research myself on these as I live on/operate a large dairy farm.

Wartsila is a great company as well.

 

Here is a video of the 2010 Cummins ISX engine running. It is fired up at 2:15. It is fairly quite as far as large diesels go. It sould also be noted that there is no muffler on this test motor and obviously no insulation around it like there would normally be when installed in a truck

I wish i could find a good video of a new duramax running, they are very queit

[ame="http://www.youtube.com/watch?v=Q-dEonuDUUM"]YouTube - Cummins 2010 ISX demo.wmv[/ame]

 

here is a great video of Cummins showing how a 2010 emissions system works

 

Methane digesters for dairys sound good however there are two sides to every story.

Theres the one side which mostly consists of environmentalists, the EPA and the DNR who want every single farm to either build their own or haul/pump their manure to a community digester.

Then there is the other side that affects farmers more. The cost. A typical methane digester for 1,000 animal units is going to run you about 1.2 million dollars. And quite frankly us farmers do not have that kind of money to just throw around on something like a digester which can take a long time to cash flow. Yes there is cost sharing available but these resources are drying up as the agencies providing the cost sharing are trying to do away with it, especially the DNR.

The problem with manure digesters is mostly in the genset. It is a third of the cost and is a very high maintnence part of the equation. If the methane is not scrubbed well the engine will fail very quickly due to the hydrogen sulfide. There are scrubbers to remove the hydrogen sulfide but these two require attention. The biggest issue is that it takes at least an hour a day for maintnence and the cost of maintnence is very high. The payment for the electricity off of them is typically around 7.5 cents per kWh which is not very high.

What we have been thinking about doing is generating the methane but using it in other ways versus an ICE genset. Turbines are much more efficient and require less maintanence but are not economical for a small scale methane digester.

One thing that a dairyman/lawyer is doing in california is collecting the methane, scrubbing it to turn the Hygrogen Sulfide into water and Sulfur fertilizer, and then pressurizing the gas and injecting it into PD&Es pipelines. He sells the methane to them at a premium as california needs to meet its renewable energy standard. He has no cost in the system either, PG&E pays for all of the equipment and maintnence. The only thing the dairy farmer has to do is put the covers on his/her lagoons. Its a very economical way to use the methane on a dairy farm. If we could do something like this on our farm we would in a heartbeat.

Now back to digesters, since small ones are not as economical as large ones, community digesters have been brought to the table and one is supposedly going up in my area. However here is how they work.

The farmer supplies his manure to the digester at no cost. The farmer is responsible for disposing of all of the liquid that the digester creates and does not get paid to dispose of it. If the farmer wants any of the solids out of the digester they have to pay for them. The farmer gets a cut of the profits of the digester from the electricity sales. In the end the farm really isnt profiting, they are just getting rid of their manure with a lower environmental impact.

Make no mistake though there are efficient cost effective methane digesters that are online. Double S dairy is one example of a digester that is running very well.

Wisconsin (where I live) is the leader in on-farm Methane Digester technology with 54 digesters currently on line and more being built. I believe there are only a couple others in other states.

The flaws with them will be resolved but for now they generally do not cash-flow.

The Cummins/Kenworth trucks have been having issues, but like with any new product this is expected. Hoefully they will get them resolved.

The DPF/SCR system reall hurts fuel economy and until Cummins gets their in cylinder tecnologies perfected, DPFs and SCR will still exist.