vn turbo

Turbocharged Direct Injection

TDI

Most of us as North American consumers associate diesel engines with trucks. Volkswagen is hoping to change that perception next year when it will introduce all-new diesel engines in virtually every model they sell. From a 100hp 1.9l engine in the Golf, Jetta and New Beetle to a 133hp 2.0l in the Passat to a full 10-cylinder TDI powerplant with over 550 lb-ft of stump pulling torque in the new Touareg sport utility vehicle, diesel technology is coming and you only need to remember three little letters: TDI.

In the spring of 1976 series production began of VW’s first diesel passenger car – the 1.5-litre, 50-bhp naturally aspirated unit for use in the Golf and Rabbit. This engine with its superior fuel economy and high levels of low-end torque created a market for itself, particularly in Europe where gasoline prices are considerably higher than they are here in America.

In the early eighties Volkswagen introduced turbocharging and bumped displacement to 1.6l bringing the horsepower to 70hp and creating the new designation of "Turbodiesel" for all its diesel models. Later in the early 90's Volkswagen introduced direct fuel injection technology calling it TDI, the initials standing for Turbocharged Direct Injection. TDI enabled engineers to make the engine quieter and more efficient which meant even better fuel economy and more power. Compared to indirect injection engines, the TDI had a fuel savings potential of up to 15 percent.

Further development lead to the adoption of a variable-geometry turbocharger which utilized variable vanes within the turbine wheel to vary the amount of air and effectively reduce turbo "lag" at low RPM's but also allow for a higher volume of air at high RPM's. Volkswagen also added charge-air cooling in the form of an air-to-air intercooler as standard equipment. This boosted the current 1.9l unit to 90hp and 110hp with impressive levels of torque and refinement.

The next major peak in TDI development was high-pressure fuel injection called "pumpe duse" in German. By utilizing upwards of 20,000 psi in certain applications, Volkswagen was able to atomized and meter fuel delivery very precisely using a unit-injector developed by Bosch. This resulted in superior economy, further increases in power and even quieter running engines. Power in the 1.9l TDI is now available in europe in 100hp, 130hp and 150hp variations.

While the 1.9l 4-cylinder TDI powerplant is the bread and butter of Volkswagen's diesel offerings, it is far from being the only unit available - Volkswagen has everything from a 3-cylinder super high-efficiency TDI unit capable of nearly 90 miles per gallon, to inline-5, V6 and V8 models and even a V10 TDI that is available in the Touareg and Phaeton luxury car in Germany with unheard of levels of refinement, power and economy.

Today diesel engines make up over 40% of the Volkswagen models sold in Europe. Here in America, TDI sales represent less than 10 percent of total sales. Volkswagen has only offered us one TDI engine choice, the 90hp 1.9l TDI with a 2-valve head and older low-pressure injection systems. Why? Well two main reasons, one, diesels don't sell well here because gasoline is cheap and two, diesel fuel in North America is far less refined than European equivalents and makes it difficult to apply strict car emission standards to the TDI engines sold here.

Currently the 90hp 1.9l TDI is available in the Golf, Jetta and New Beetle and is rated at 42 mpg city and 49 mpg highway. With a 14.5 gallon tank and a 49 mph highway rating, you could theoretically drive over 710miles on a single tank of fuel. These models are only sold in limited numbers in states that have stricter emission standards such as California, Maine, Massachusetts, Vermont and New York so they don't affect Volkswagen's CAFE fleet standards too adversely but are otherwise available in the 45 remaining states.

While Volkswagen owners tend to be an enthusiastic bunch, TDI owners have elevated themselves to near-cult like status. Owner sites like Fred's TDI Club (www.tdiclub.com) have cropped up as a means for TDI owners and fans alike to communicate, share war stories, help each other with maintenance and other issues and even seek new ways to extract even more power from the existing 90hp 1.9l TDI.

TDI fans have been clamoring for the latest TDI technology available in Europe to find its way over to our shores. So far the new generation of pumpe duse/high pressure TDI engines have not been offered here due to the sub-par diesel fuel we have available. Particulate standards are nearly impossible to meet with the fuel available here, but Volkswagen's engineers have finally devised a way to get some of the new engines to run properly and pass emissions in 45 states. We'll start to see these new TDI engines starting with model year 2004 which we will cover in depth in our fifth installment.

In anticipation of these new TDI offerings coming to North America we set out to Germany last year to drive a number of the latest and greatest TDI models available in that market. We drove everything from the phenomenally economical Lupo 3L TDI to the tire shredding 150hp 1.9l TDI Bora/Jetta (with the same torque as a 3.2l VR6!) to the foundation moving V-10 TDI in the Touareg. Over the next several installments we will be highlighting a number of these TDI equipped vehicles to give you a feel for the different TDI offerings available in Europe and a little preview of what to expect in 2004.

Radiator Pressure cap

Radiator Pressure cap

    Beating the Heat: Advantage of a High Pressure Radiator Cap
 Spoon, Mugen, TRD, and about two dozen other ‘big name’ companies all sell these “High Pressure” radiator caps. However, if you ask the average person what they actually do, you’ll be met with cricket chirps.

Most imports use 1.1 kg/cm2 radiator caps while these aftermarket pieces are typically 1.3 kg/cm2. These caps are also available for domestics and some exotics as well, but the same principle applies regardless of the make/model of car. Sometimes they are rated in the “bar” unit.  The conversion factor is 1.02, so for the purposes of this article, because kg/cm2 is more awkward to write, I will say 1.1 bar and 1.3 bar. 1.1 bar is nearly exactly equal to 1.1 kg/cm^2. So, yes, I realize import caps are rated in the metric unit, but I’m going to use bar instead to make my writing a little easier.

These caps look cool, and they’re sold by big names – but let’s look at what they actually do and why you may or may not want one.

A Little Technical Background
To understand why the higher pressure radiator caps might be useful, we first need to understand something about the fluid inside the cooling system.

In an ideal world, engines would be cooled by straight water with no antifreeze added. Water is an excellent cooling agent and is extremely efficient at carrying heat away from the engine and then exchanging that heat with the air via the radiator.

However, water has a few properties that make it imperfect as an automotive coolant. For one, it has a relatively high freezing temperature at 32 degrees Fahrenheit. Freezing would be bad enough but water also has the unique property that it expands at its freezing (which if you’ve ever left a soda in the freezer before, you know why that’s bad). It also has a relatively low boiling point at 212 degrees Fahrenheit.

Since most engines are operating at a temperature of around 185-205 degrees, that only gives us a small amount of wiggle room before boiling would occur. Boiling is bad for a number of reasons which I won’t get too into here, but, steam/bubbles in coolant actually insulate coolant from the combustion chamber and would render the coolant useless at cooling the hot engine. It can also cause water pump failures amongst other damage via a process called cavitation.

Water is corrosive and it will gradually eat away at seals and cause metal inside your engine to deteriorate. Finally, it isn’t a very good lubricant and the water pump and seals in your cooling system rely on other compounds in your coolant to provide those properties.

So, we generally add antifreeze to distilled water to create the coolant we run in the car.

Antifreeze both keeps water from freezing in the winter (by lowering the freezing point of the water) and at the same time raises the boiling point of the water. A 50/50 mixture as we typically use actually gives us a freezing point of -35 degrees Fahrenheit and a boiling point of 223.

The trade off for the extra wiggle room of course is that antifreeze is not a very efficient heat exchanging fluid. In fact, 100% antifreeze in your cooling system would be an absolutely terrible idea. When you add antifreeze to water, the ability to cool evenly and quickly drops. Besides that, up until about 60% coolant, you do gain boiling point and freezing point. However, past 60% coolant to water, you start to go the other way again, sharply.

While we’d love to run 100% distilled water in the cooling system, we can’t because of corrosion and boiling/freezing points. We also don’t want to use 100% antifreeze because it would be a poor cooling fluid. Therefore, we need a compromise, which is usually a 50/50 ratio of the two fluids mixed together.

The Role of Pressure
 But, back to the radiator cap. As the coolant gets hot it expands creating pressure in the system. The hotter things get, the more pressure created. The radiator cap allows pressure to build up in the cooling system and will eventually vent that pressure to the overflow bottle as the need arises. The cap does this by a spring loaded valve which serves as a pressure relief valve at a rated pressure. You’ll notice that there’s a plunger on the bottom of the cap. As pressure builds, it pushes up on that valve until eventually the valve is opened far enough for coolant to flow out of the tube connected at the radiator fill neck. It closes again when the pressure has dropped to the desired level.

This tank is there just to catch the coolant and store it until things cool back down, when a vacuum will be created and most of the coolant will return to the cooling system.

Pressure actually increases the boiling point of a fluid as you may know from high school physics class. The pressure literally forces the liquid to remain a liquid longer and does not allow it to transform into vapor. All modern automotive cooling systems are under pressure, completely regulated by the radiator cap. 1.1 bar is roughly 15psi, and 1.3 bar is around 18psi.

How much does the pressure raise the boiling point? Well, it’s about 2-3 degrees for every psi that we increase the pressure of the system. Therefore, by using a 1.1 bar cap we make the average boiling point of a stock cooling system somewhere closer to  around 257-260 degrees.

When we change from a a 1.1 bar to 1.3 bar cap, we gain 0.2 bar or roughly 2.9psi of pressure. So, we effectively get 8.7 degrees (or around that) on top of the 257-260 degrees  before we might experience boiling coolant in the system.

So if some extra pressure is good, why not a lot? Well, it may seem obvious, but the cooling system on your car is rated to a certain pressure. The radiator cap is designed to be the weak point in your cooling system so it can safely vent pressure, you don’t want to use a cap that is so resistant to venting pressure that it causes some other part of the system to become the weak point.

What does it DO for you?
Under normal operating conditions, with everything else untouched it gives you a small amount of extra protection against localized boiling and therefore hot spots in the cylinder walls and cylinder head. If you’re running a 50/50 ratio of antifreeze to water and aren’t overheating, there is no real measurable benefit.

However, when mixed with a slight change in coolant, these caps can actually add quite a bit of cooling efficiency to your car, especially for hot summer track days. It’s a cheap tweak that can give you some extra insurance against engine failure or detonation in extreme conditions, or, make you legal to be on certain tracks.

What these caps can be used to do, is run  less antifreeze and more distilled water in your cooling system in the summer. It can also be used to run nearly straight water and water wetter (an additive which… increases the wetting ability of water.) for the track. The benefit on the track being two-fold. Some tracks do not allow you to use antifreeze as it is literally slick as snot if it leaks or spews onto the track. The other benefit is that straight water as we discussed before is the most efficient cooling fluid. Add a product called Water Wetter and that can be a really powerful combination.

So let’s get to the point…

Remember that a 50/50 ratio of coolant has a boiling point of 223 degrees. Straight water has a boiling point of 212 degrees. Both however are boosted significantly by the pressure in the system. A standard 1.1 bar cap adds 48 degrees to the boiling point of either fluid. So the coolant in your car will not actually boil until ~260 degrees, or ~271 degrees if it has antifreeze mixed in. Adding the additional 0.2 bar of pressure gives us another 8.7 degrees in both cases.

By upping our cooling system pressure to 1.3 bar we gain about 8.7 degrees. Antifreeze only adds 11 degrees to our boiling point, so the main reason for running a 1.3 bar cap is to run straight distilled water (with water wetter to prevent corrosion) or a significantly reduced antifreeze ratio without danger of boiling over. Specifically, in the summer months.

So why not run it this way all the time? Well, let’s not forget the freezing point. While the pressure cap trick gives us a higher boiling point, it does not a thing for freezing point. If your area doesn’t get down to negative temperatures in the winter, you can run a decreased ratio of antifreeze to coolant if you like all year round. However, I’d still run 50/50 in the winter. The good news is, in the winter, there’s less need for excellent cooling as air intake temps and ambient temps help you out a lot more than in the summer.

So Should I Get One or Get Rid of Mine?

 Well, they’re generally inexpensive, around $20-30. I would never pay more than maybe $40 and really, you can get just about any old 1.3 bar cap that fits for around $10 that will do the job just fine.If an OEM tuning house sells one for your car, you may want to go with that one – the cap is simple but it’s extremely important it functions properly. OEM quality is important here.

They are a small amount of insurance against possible overheating, especially for tracked cars or for excessive idling in the hot summer months. Add another $10 for a bottle of water wetter as well. For a daily driver, the extra pressure would only be particularly helpful if running a modified coolant ratio. Installing one won’t hurt anything. If you ever do approach boiling point, they’ll give you a little more insurance against it, and they’ll keep the coolant doing its job longer before the bubbles in the fluid create problems.

For a car that sees track time, specifically road race time, it would be a good cheap upgrade to your cooling system. Especially when mixed with the straight distilled water+water wetter or reduced antifreeze ratio combo.

If you do run straight distilled water, make sure you put water wetter in with it, or you will create corrosion problems and the water wetter will make the distilled water more efficient as well.

In particularly hot areas with engines that are running high compression or boost, a 1.3 bar radiator cap, water wetter and a reasonable coolant ratio or distilled water setup would be a good “stock upgrade” to help prevent detonation. Granted, if your engine is fairly close to stock, you don’t need to worry about detonation as long as you run the right fuel as dictated in your factory service manual.

In closing, if you want to run the same setup all year round and want to be extra safe, run 50/50 antifreeze with Water Wetter (it improves coolant efficiency and especially helps evenly cool the cylinder head), add a 1.3 bar cap for good measure.

In a later article I will discuss other common ‘coolant system upgrades’ like low temperature thermostats, fan switches, as well as if/when you should upgrade your radiator.

Types of Oil Pumps

 Gear-type oil pump

Gear-type oil pumps have
a primary gear that is driven by an external member, and which drives a companion
gear.  Oil is forced into the pump cavity, around each gear, and out the other side
into the oil passages.  The pressure is derived from the action of the meshed gear
teeth, which prevents oil from passing between the gears, forcing it around the
outside of each gear instead.  The oil pump incorporates a pressure relief valve, a
spring-loaded ball that rises when the desired pressure is reached, allowing the
excess oil to be delivered to the inlet side of the pum

 
Rotor-type oil pump

A rotor-type oil pump for sucking and discharging oil to be supplied to a variety of oil-requiring parts of an automotive engine. The oil pump comprises a generally annular outer rotor which is rotatably disposed in a pump casing. A generally annular inner rotor is disposed eccentrically inside the outer rotor and has an external gear which is partly in mesh with the internal gear of the outer rotor. The outer rotor is designed such that stress at the tooth base section of the internal gear is generally equal to stress at the tooth base section of the external gear of the inner rotor in their dynamic condition, thereby reducing the thickness of the tooth base section of the outer rotor.

Crescent type oil pump 

 

Vane Type oil pump

Lubrication System

how a engine lubrication system functions and talks about the main components for lubricating an engine (oil pump, oil filter, oil store, oil splash, etc


Functions of oil
   
Oil reduces unwanted friction. It reduces wear on moving parts, and helps cool an engine. It also absorbs shock loads and acts as a cleaning agent.

 Viscosity
   
Viscosity rating indicates flow rate of oil at a given temperature. There are many grades. Thin oils tend to be for cold conditions. Oil with improver is called multi-grade or multiple-viscosity oil.

 Oil additives
   
Different additives do different jobs. They can inhibit corrosion, foaming and oxidation, and act as dispersants.

Synthetic oils
   
Synthetic oils offer better protection against engine wear and can operate at higher temperatures. They have better low temperature viscosity, are chemically more stable and allow for closer tolerances in engine components without loss of lubrication.

Lubrication systems
   
The lubrication system
   
The lubrication system is designed to keep the components in the engine lubricated and to reduce friction.

Splash system
   
In the splash lubrication system, a dipper or slinger splashes oil through the internal parts of the engine. Oil is also splashed up to the valve mechanism.

 Pressure system
   
In force-feed lubrication, pressure forces oil around the engine. In a wet-sump system, oil is kept in the sump ready for the next use. In a dry sump system, oil falls to the bottom of the engine and a scavenge pump sends it to an oil tank.

 2-stroke engine premix fuel systems
   

Most 2-stroke gasoline engines use a set gasoline-oil mixture for lubrication. As the air, fuel and oil enter the crankcase, the fuel evaporates, leaving behind enough oil to keep parts coated and lubricated.

 2-stroke engine oil injection systems
  
An oil injection system doesn't need the oil and gasoline mixed manually. An engine-driven oil pump takes oil from a tank and pumps a measured amount directly into the engine where it mixes with the fuel and lubricates the internal engine parts.

 Rotary engine lubrication system

In addition to normal internal lubrication, the rotary engine uses oil injection. A pump injects a measured amount into the intake manifold. Oil from these nozzles goes to the engine and lubricates the rotor seals.

Corrosion/noise reduction
   
Engine oil performs many other functions apart from lubricating moving components. Two other functions are corrosion protection and noise suppression.

Lubrication system components
   
Sump
   
The sump is at the base of an engine. It can be used as a storage container in a 'wet sump system'.

 Oil collection pan
   
An oil collection pan is used in 'dry sump systems' prior to being returned to an oil tank.

 Oil tank
   
The oil tank is part of the dry sump lubrication system and is used for oil storage.

Pickup tube
   
A pickup tube is used to provide a means of collecting oil for the oil pump.

 Oil pump
   
Oil pumps deliver oil under pressure to the internal engine parts. In a rotor-type oil pump, an inner rotor drives an outer one. Pressure differences force the oil to move. Geared oil pumps use a similar principle.

 Oil pressure relief valve
   

The pressure relief valve is used to prevent damage to an engine due to too much oil pressure.
 
Oil filters
   
The oil filter helps to clean the oil in the system. If the filter clogs, a valve opens and directs unfiltered oil to the engine. Most oil-filters on diesel engines are larger than those on similar gasoline engines.

Spurt holes & galleries
   
Spurt holes and galleries are used to deliver oil from the oil pump to various components and bearings in the engine.

Oil indicators
   
Oil indicators are used to check when there are safe oil levels in an engine.

Oil cooler
   
An oil cooler cools oil prior to its reuse in the engine.

Lubrication procedures
   
Checking engine oil

The objective of this procedure is to show you how to check and adjust engine oil level and condition. Make sure the vehicle is on a level surface and the engine is off before taking a reading. If you don't, you'll get inaccurate readings.

 Draining engine oil

Oil loses its clean, fresh look very quickly and yet may still be serviceable. The best guide to changing oil is knowing the vehicle's mileage and period of time since the last oil change. The objective of this procedure is to show you how to safely drain engine oil.

Replacing an oil filter

The objective of this procedure is to show you how to replace an oil filter to the manufacturer's specifications. Before removing an oil filter, first refer to the Service Manual for the vehicle and identify the type of filter required.

Refilling engine oil
   
The objective of this procedure is to show you how to safely refill engine oil. The service manual or the owner's manual will also tell you the correct grade of oil for the vehicle, and the quantity you will need to fill the engine.

cav rotary pump (epic)

Careful section of a CAV rotary pump for training purposes, showing all its operating parts. The transfer pump, the speed governor, the automatic advance regulator, the hydraulic sensor device, the fuel circuit and the pumping small piston are clearly shown. It is operated by hand through a hand wheel.

It is supplied complete with an indirect injector and mounted on an elegant laminated plastic base.

New vehicle air condition system

air condition system
 Vehicles are found to have primarily three different types of air conditioning systems. While each of the three types differ, the concept and design are very similar to one another. The most common components which make up these automotive systems are the following: COMPRESSOR, CONDENSER,EVAPORATOR, ORIFICE TUBE, THERMAL EXPANSION VALVE , RECEIVER-DRIER,ACCUMULATOR.
 Note: if your car has an Orifice tube, it will not have a Thermal Expansion Valve as these two devices serve the same purpose. Also, you will either have a Receiver-Dryer or an Accumulator, but not both.
 COMPRESSOR
 Commonly referred to as the heart of the system, the compressor is a belt driven pump that is fastened to the engine. It is responsible for compressing and transferring refrigerant gas. The A/C system is split into two sides, a high pressure side and a low pressure side; defined as discharge and suction. Since the compressor is basically a pump, it must have an intake side and a discharge side. The intake, or suction side, draws in refrigerant gas from the outlet of the evaporator. In some cases it does this via the accumulator. Once the refrigerant is drawn into the suction side, it is compressed and sent to the condenser, where it can then transfer the heat that is absorbed from the inside of the vehicle.
 CONDENSER
 This is the area in which heat dissipation occurs. The condenser, in many cases, will have much the same appearance as the radiator in you car as the two have very similar functions. The condenser is designed to radiate heat. Its location is usually in front of the radiator, but in some cases, due to aerodynamic improvements to the body of a vehicle, its location may differ. Condensers must have good air flow anytime the system is in operation. On rear wheel drive vehicles, this is usually accomplished by taking advantage of your existing engine's cooling fan. On front wheel drive vehicles, condenser air flow is supplemented with one or more electric cooling fan(s). As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As the gas cools, it condenses and exits the bottom of the condenser as a high pressure liquid. . EVAPORATOR
 Located inside the vehicle, the evaporator serves as the heat absorption component. The evaporator provides several functions. Its primary duty is to remove heat from the inside of your vehicle. A secondary benefit is dehumidification. As warmer air travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is perfectly normal. The ideal temperature of the evaporator is 32 Fahrenheit or 0 Celsius. Refrigerant enters the bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. This heat is then carried off with the refrigerant to the outside of the vehicle. Several other components work in conjunction with the evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32 F. Temperature and pressure regulating devices must be used to control its temperature. While there are many variations of devices used, their main functions are the same; keeping pressure in the evaporator low and keeping the evaporator from freezing; A frozen evaporator coil will not absorb as much heat.

 PRESSURE REGULATING DEVICES
 Controlling the evaporator temperature can be accomplished by controlling refrigerant pressure and flow into the evaporator. Listed below, are the most commonly found. ORIFICE TUBE The orifice tube, probably the most commonly used, can be found in most GM and Ford models. It is located in the inlet tube of the evaporator, or in the liquid line, somewhere between the outlet of the condenser and the inlet of the evaporator. This point can be found in a properly functioning system by locating the area between the outlet of the condenser and the inlet of the evaporator that suddenly makes the change from hot to cold. You should then see small dimples placed in the line that keep the orifice tube from moving. Most of the orifice tubes in use today measure approximately three inches in length and consist of a small brass tube, surrounded by plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to become clogged with small debris. While inexpensive, usually between three to five dollars, the labor to replace one involves recovering the refrigerant, opening the system up, replacing the orifice tube, evacuating and then recharging. With this in mind, it might make sense to install a larger pre filter in front of the orifice tube to minimize the risk of of this problem reoccurring. Some Ford models have a permanently affixed orifice tube in the liquid line. These can be cut out and replaced with a combination filter/orifice assembly.
 THERMAL EXPANSION VALVE
 Another common refrigerant regulator is the thermal expansion valve, or TXV. Commonly used on import and aftermarket systems. This type of valve can sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. Several variations of this valve are commonly found. Another example of a thermal expansion valve is Chrysler's "H block" type. This type of valve is usually located at the firewall, between the evaporator inlet and outlet tubes and the liquid and suction lines. These types of valves, although efficient, have some disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with debris, but also have small moving parts that may stick and malfunction due to corrosion.

 RECEIVER-DRIER
 The receiver-drier is used on the high side of systems that use a thermal expansion valve. This type of metering valve requires liquid refrigerant. To ensure that the valve gets liquid refrigerant, a receiver is used. The primary function of the receiver-drier is to separate gas and liquid. The secondary purpose is to remove moisture and filter out dirt. The receiver-drier usually has a sight glass in the top. This sight glass is often used to charge the system. Under normal operating conditions, vapor bubbles should not be visible in the sight glass. The use of the sight glass to charge the system is not recommended in R-134a systems as cloudiness and oil that has separated from the refrigerant can be mistaken for bubbles. This type of mistake can lead to a dangerous overcharged condition. There are variations of receiver-driers and several different desiccant materials are in use. Some of the moisture removing desiccants found within are not compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the receiver-drier. Newer receiver-driers use desiccant type XH-7 and are compatible with both R-12 and R-134a refrigerants.
 ACCUMULATOR
 Accumulators are used on systems that accommodate an orifice tube to meter refrigerants into the evaporator. It is connected directly to the evaporator outlet and stores excess liquid refrigerant. Introduction of liquid refrigerant into a compressor can do serious damage. Compressors are designed to compress gas not liquid. The chief role of the accumulator is to isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers, also remove debris and moisture from a system. It is a good idea to replace the accumulator each time the system is opened up for major repair and anytime moisture and/or debris is of concern. Moisture is enemy number one for your A/C system. Moisture in a system mixes with refrigerant and forms a corrosive acid. When in doubt, it may be to your advantage to change the Accumulator or receiver in your system. While this may be a temporary discomfort for your wallet, it is of long term benefit to your air conditioning system

Diesel Electronic Unit Injector

The unit injector combines a high-pressure pump and nozzle with a solenoid valve to form compact assembly. As a result, high-pressure lines are no longer necessary and injection can be controlled by the integrated and extremely precise solenoid valve at pressures of up to 2000 bar. Each cylinder has a unit injector fitted between the valves in the cylinder head. The unit injector is used in both passenger cars and commercial vehicles. The Bosch Unit Injector system was first used in the VW Passat TDI in 1998, after which it rapidly found favour within the VW range. With the V10 TDI, VW recently presented what is currently the most powerful diesel engine for use in a car.

Diesel injection pump

Robert Bosch has contributed to Diesel In-Line Fuel-Injection Pumps: Bosch Technical Instruction as an author. Robert Bosch GmbH is ranked among the world's major equipment suppliers. The Bosch experts that make up the editorial team come from the relevant divisions of Bosch and are at the forefront of technical developments in their field. Bosch demonstrates its leading competence in automotive technology through the sheer number of its applications for patents and patented designs. inline pump

The diesel fuel pump is a fairly complex and sturdy mechanism. In fact, it is the most complex diesel engine part. Additionally, a diesel fuel pump must be durable enough that it can withstand the pressure of the compressed air, and the heat of the injection process. The fine mist of fuel needed for the proper ignition must be maintained by the diesel fuel pump under these extreme conditions. Diesel fuel pumps may be located just about anywhere on the engine, depending on the manufacturers design. Much experimentation has been done over the years regarding the most effective placement of the diesel fuel pump. So far it seems that so long as the pump is mounted on the engine, it will effectively deliver fuel to the cylinders. A gasoline fuel pump, on the other hand, may be mounted anywhere in the engine compartment or along the fuel distribution system. Depending on the location and design of the diesel fuel injector pump, pre-combustion chambers, customized induction valves, and other systems are often used in the injection process. These injection enhancers often aid in circulating, or swirling the air inside the cylinder for more efficient combustion. Just as with any engine fuel injection system, diesel fuel pumps are constantly being improved to be more efficient and less costly.

Common Rail System

The common rail system accumulates high-pressure fuel in the common rail and injects the fuel into the engine cylinder at timing controlled by the engine ECU, allowing high-pressure injection independent from the engine speed. As a result, the common rail system can reduce harmful materials such as nitrogen oxides (NOx) and particulate matter (PM) in emissions and generates more engine power. DENSO leads the industry in increasing fuel pressure and maximizing the precision of injection timing and quantity, achieving cleaner emissions and more powerful engines. DENSO’s common rail systems are supplied to a variety of vehicles including passenger cars and commercial vehicles. DENSO Technology – Leading the World In 1995, DENSO launched the world’s first common rail system for trucks. In 2002, DENSO launched a 1,800-bar common rail system that achieved the industry’s highest injection pressure, and five-time multiple injections at a high accuracy. This system comfortably cleared EURO4 emission regulations without a diesel particulate filter. Benefits and Features DENSO’s common rail system can inject fuel at up to 1,800 bar, significantly reducing the concentration of PM in emissions. DENSO’s new injectors can perform five injections during each combustion stroke. The five times multiple injections, including pilot injection with a predetermined small fuel quantity, reduce PM and NOx in emissions, and achieve quietness at idling equivalent to gasoline-powered engines. The high fuel injection pressure is generated by the supply pump, which is the lightest in the world for passenger car common rail systems.

diesel engine

internal combus­tion engines designed to convert the chemical energy available in fuel into mechanical energy. This mechanical energy moves pistons up and down inside cylinders. The pistons are connected to a crankshaft, and the up-and-down motion of the pistons, known as linear motion, creates the rotary motion needed to turn the wheels of a car forward. Both diesel engines and gasoline engines covert fuel into energy through a series of small explosions or combustions. The major difference between diesel and gasoline is the way these explosions happen. In a gasoline engine, fuel is mixed with air, compressed by pistons and ignited by sparks from spark plugs. In a diesel engine, however, the air is compressed first, and then the fuel is injected. Because air heats up when it's compressed, the fuel ignites. The diesel engine uses a four-stroke combustion cycle just like a gasoline engine. The four strokes are: Intake stroke -- The intake valve opens up, letting in air and moving the piston down. ­ Compression stroke -- The piston moves back up and compresses the air. Combustion stroke -- As the piston reaches the top, fuel is injected at just the right moment and ignited, forcing the piston back down. Exhaust stroke -- The piston moves back to the top, pushing out the exhaust created from the combustion out of the exhaust valve. Remember that the diesel engine has no spark plug, that it intakes air and compresses it, and that it then injects the fuel directly into the combustion chamber (direct injection). It is the heat of the compressed air that lights the fuel in a diesel engine. In the next section, we'll examine the diesel injection process.

New Turbocharger Ball Bearing Technology

September 4, 2009 --The Comp Turbo CT3B turbocharger is relatively new on the scene, is dynamite in a small package and has a bearing system that utilizes the latest in ball bearing technology. Racing applications need turbochargers that accelerate at the fastest possible rate and the CT3B bearing system allows it to do just that. The acceleration rate of a turbocharger is a function of the rotor inertia and the friction losses in the bearing system. Conventional bearing systems have floating sleeve bearings that have an inner and outer oil film fed by lube oil under pressure from the engine lubricating system. They also must employ a stationary thrust bearing that is also fed by lube oil under pressure from the engine. The friction loss attributed to a stationary thrust bearing is proportional to the fourth power of the radius and can amount to several horsepower at the high speed at which turbochargers operate. The oil films in conventional sleeve bearing systems have significant viscosity that produces appreciable friction losses due to oil film shear when the turbocharger rotor accelerated and running at high speed. The friction losses in the sleeve bearings and in the thrust bearing result in mechanical efficiencies in the middle 90% range in conventional turbochargers. There is little or no oil film shear in ball bearings which operate with rolling friction only so that the CT3B accelerates much faster than turbochargers using sleeve bearings systems. The CT3B bearing system is a proprietary design that is unique in the industry. It utilizes full compliment, angular contact ball bearings with ceramic balls. Compared with steel balls, ceramic balls in ball bearings have a number of advantages. Bearing service life is two to five times longer. They run at lower operating temperatures and allow running speeds to be as much as 50% higher. The surface finish of ceramic balls is almost smooth, producing lower friction losses and lower vibration levels. There is less heat buildup during high speed operation, they exhibit reduced ball skidding and have a longer fatigue life. All these characteristics make ceramic ball bearings ideal for use in turbochargers where they must operate at very high speeds and survive in a high temperature environment. The Full compliment bearings do now use a cage to position the balls and this additional feature, combined with the ceramic material provides a combination that has minimal friction losses. The mechanical efficiency of the CT3B turbo can approach 99%, and this contributes to rotor acceleration rates that have been shown to be faster than competition. The angular contact bearings are mounted in an elongated steel cylinder that is free to rotate in the bearing housing. The outside diameter of the cylinder is fed with lube oil and this outer oil film provides a cushion against shock and vibration. Two angular contact bearings are mounted in tandem on the compressor end of the cylinder in an arrangement that carries rotor thrust in both axial directions. A single angular contact bearing is slid ably mounted under pre- load on the turbine end of the cylinder and is free to move axially with shaft elongation when heat is conducted down the shaft from the hot turbine wheel. The elongated steel cylinder containing the angular contact bearings represents complete bearing system and can be inserted and/or removed as an assembly making the CT3B turbocharger fully upgradeable, serviceable and re-buildable. Racing Applications require a turbocharger that builds boost as rapidly as possible, thus allowing the engine develop high torque at low engine speeds and with boost capability that can produce very high maximum power output .The CT3B turbocharger does exactly that. For example when mounted on one dragster, the CT3B produced 1.7 bar boost in two tenths of a second and developed 650 HP ready for takeoff. Now that’s phenomenal response and very impressive. In street applications, the acceleration rate of a vehicle equipped with a CT3B turbocharger is enhanced and moves the engine out of inefficient operating regimes more rapidly. An improvement in number of gallons of fuel used is the usual result when a vehicle is accelerated faster. Under steady-state operation, the lower HP losses in the CT3B ball bearing system means power is available to the turbocharger compressor which results in higher intake manifold pressure. In most cases, higher boost can make an additional contribution to improving engine fuel consumption. Comp Turbo can supply the CT3B turbocharger with various compressors and turbine wheel trims to tailor its performance so that it matches specific engine application requirements; whether they be racing, street or stationary. In addition, the CT3B will be followed in the near future by other model sized now under development at Comp Turbo. These new models will utilize the proprietary technology that has been designed into the successful CT3B to complete a line of high performance turbochargers utilizing the many advantages of ceramic ball bearings. They will also accelerate like greased lightning to produce the ultimate in engine and vehicle response

2 stroke engine

Stroke: Either the up or down movement of the piston from the top to the bottom or bottom to top of the cylinder (So the piston going from the bottom of the cylinder to the top would be 1 stroke, from the top back to the bottom would be another stroke) Induction: As the piston travels down the cylinder head, it 'sucks' the fuel/air mixture into the cylinder. This is known as 'Induction'. Compression: As the piston travels up to the top of the cylinder head, it 'compresses' the fuel/air mixture from the carburetor in the top of the cylinder head, making the fuel/air mix ready for igniting by the spark plug. This is known as 'Compression'. Ignition: When the spark plug ignites the compressed fuel/air mixture, sometimes referred to as the power stroke. Exhaust: As the piston returns back to the top of the cylinder head after the fuel/air mix has been ignited, the piston pushes the burnt 'exhaust' gases out of the cylinder & through the exhaust system. Transfer Port: The port (or passageway) in a 2 stroke engine that transfers the fuel/air mixture from the bottom of the engine to the top of the cylinder