Turbo Manual

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Turbo Manual

Turbo Manual

TurboManuel

Turbo Manual� �

1. INTRODUCTION

Dear reader,

This handbook on turbochargers is presented to you by Turbo World. What can you expect from it? As well as a lot of technical details, of course, the various advantages and disadvantages of turbochargers are also described. The history of the turbo is outlined and a lot of facts and know-how are divulged.

This handbook is actually intended for two sorts of person: for those already familiar with the technology, and for those who would like to know more about the technology. Flicking through the pages will improve your knowledge. You will come across questions that are yearning for answers, and answers that will in turn evoke further questions. Everyone can learn something from it, and this makes the free handbook truly valuable. Something to save. Something for on the counter, in the waiting room or in the work canteen.

We at Turbo World have compiled this handbook for you with great enthusiasm. We hope that you enjoy working through it just as much as we did making it. Should you have any questions, don't hesitate to contact us by telephone and/or via our website. Who knows, perhaps your question or tip will appear in the next publication. We wish you a very pleasant read!

Jeroen VelthuisManaging director Turbo World

CONTENTS

1. INTRODUCTION

�. HISTORY History of the turbo

�. TECHNIQUE The Combustion Engine Pressure-Charging Pulse Pressure-Charging Mechanical Pressure-Charging Exhaust Gas Pressure-Charging Sequential Pressure-Charging

4. THE TURBO Advantages and Disadvantages Construction and Components The Compressor The Internal Mechanism (Central Hub Rotating Assembly) The Turbine

5 ADDITIONAL COMPONENTS The Intercooler Parallel Twin-Turbo System Serial Twin-Turbo System

6. DEVELOPMENTS THROUGH THE YEARS Turbo Electronics Variable Turbine Technology Garrett The VNTOP

7. TURBO DAMAGE To Replace or Not to Replace? Determining the Cause of the Complaint Insufficient Lubrication Impact from Objects Fouling of Engine Oil Excessive Counterpressure from the Exhaust Gas Excessive Exhaust Gas Temperature Formation of Cracks Material Fatigue 8. PROBLEMS AND SOLUTIONS Table: Causes and Solutions

9. THE QUALITY CHECkLIST

10. IN THE WORkSHOP The Cleaning Process The Surface Treatment Process The Control Process The Balancing Process

11. DO THE TURBO TEST Multiple Choice Test

Turbo Manual4 5

Every engine delivers a certain amount of power. In a combustion engine that power is delivered through a combination of fuel, oxygen and the ignition temperature. Changes in any of these three factors will affect the engine's power.

In order to produce greater power at constant temperature, more

fuel and oxygen have to be supplied. This requires a greater cylinder

volume and makes the engine bigger, heavier and more expensive.

The speed at which fuel and oxygen are supplied can also be

increased. This will lead to an increase in the number of revolutions.

The disadvantage of this approach, however, is that engine parts

wear down quicker.

Pressure ChargingEngine power can be increased by compressing the air needed for

combustion before it enters the engine. This compressed air can be

supplied in several ways: pulse pressure charging, exhaust gas pressure

charging (turbocharging), mechanical pressure charging (supercharging)

or sequential pressure charging (sequential turbocharging).

Pulse Pressure Charging

Pulse pressure charging obtains the pressure capacity required from

the exhaust gas, although there is also a mechanical drive between the

engine and the pressure charger. This form of pressure charger is used

very little these days. .

Mechanical Pressure ChargingIn the case of supercharging, or mechanical pressure charging, the

necessary pressure capacity comes from the crankshaft, which is the

mechanical connection between the engine and the pressure charger.

There are types of mechanical pressure chargers with and without

internal compression.

One of the most used types of compressor without internal compression

is the Roots-compressor, named after the Roots brothers. This type of

compressor - that was developed further by Mercedes - acts as pump:

if the compressor delivers more air than the engine can draw in itself,

there is excess pressure in the inlet.

The spiral-compressor - also referred to as the G-lader or scroll-type

compressor - is an example of a compressor that does make use of

internal compression. Due to the high costs, production of this type has

since been ceased.

Exhaust Gas Pressure ChargingTurbos with exhaust gas pressure charging work according to the

constant pressure principle. The turbocharger is in fact nothing more

than a compressor driven by exhaust gas. The turbine is set in motion

by the energy present in the exhaust gas. The greater the energy in

the exhaust gas, the greater the number of revolutions achieved by

the turbine.

Sequential Pressure ChargingThe sequential pressure charger system is one of the newest

developments in the field of turbochargers. The turbo process begins

with a small turbo, after which the air supply to the engine is taken

over by a large turbo. The result is a diesel engine with 20% extra

power, greater torque capacity at lower revolutions and a wider range

of speeds.

�. TECHNIQUES

The turbo has existed for about as long as the combustion engine. Gottlieb Daimler and Rudolf Diesel studied new possibilities for increasing power and reducing fuel usage by the application of compressed air as early as 1885 and 1896, respectively.

The principle of the exhaust gas compressor or turbo was developed

and recorded by the Swiss engineer Alfred J. Büchli in 1905. Büchli

was able to achieve a 40% gain in power, and this led to the formal

introduction of the turbocharger in the automobile industry.

The manufacturer Swiss Machine Works Saurer produced the

first turbocharger for a truck in 1938. The first standard built-in

turbocharger was introduced by Swedish truck manufacturer Scania

in 1961. This was an incredibly revolutionary step at the time,

since other brands of turbo didn't seem to be particularly reliable.

Turbochargers for passenger cars followed a year later. Due to their

lack of reliability, however, they were soon taken off the market.

The turbocharger made its first appearance in autosports in the

1970's. The turbocharger was a desired item, and in particular

in Formula 1. Partly as a result of this, the term "turbo" was

integrated into the public at large. Car manufacturers responded

to this by offering their top models with turbos. The plaudits came

too soon, however, as the first commercial turbos still weren't very

economical. Furthermore, many drivers found the 'turbolag' - a

short delay when accelerating - to big.

The turbocharger's big moment for trucks came in 1973, just after

the first oil crisis. From that moment on, the turbo began an advance

that continues to this day. At the end of the 1980's an increasing

environmental awareness ensured for stricter emission standards.

This resulted in many trucks being produced with turbochargers. At

the present time practically all truck engines have a turbo.

The real breakthrough for turbochargers in passenger cars came

in 1978, the year the Mercedes Benz 300 SD was introduced

(photo 2.1). The VW Golf turbo diesel followed in 1981. This was an

important milestone because it was the first time a diesel engine

(with turbo) was able to deliver almost nearly as much power

as a petrol engine without a turbo. Furthermore, the emission of

dangerous substances was greatly reduced.

�. HISTORY Of THE TURBOCHARGER

2.1 Engine Mercedes 300 Turbo Diesel

Turbo Manual6 7

Cars should really have two engines: one for quick acceleration and one for constant speed. However, two engines in a car would be too much of a good thing and the installation of a turbo offers a solution to this dilemma.

The operation of a turbo is based on the supply of extra air to the

engine under pressure, which provides the engine with greater

power and thus allows it to deliver a better performance. The

technology behind this may seem complicated at first glance, but it

is founded on simple principles.

Combustion of fuel and oxygen takes place in the cylinders. The

exhaust gas that flows out of the cylinder drives the turbine wheel

in the turbo. The turbine wheel, connected by a rigid shaft, drives a

compressor wheel. The rotating compressor wheel in turn draws in

air and compresses it. When the inlet valve opens, the compressed

air flows into the cylinder (photo 4.1).

There is more or less a power equilibrium between the turbine

and the turbo compressor. The greater the energy delivered by the

exhaust gas, the greater number of revolutions are achieved by the

turbine and thus the compressor. In this way more air is pumped

into the engine and more energy can be delivered.

The turbo and engine are not mechanically connected. They are

connected only by means of inlet air and exhaust gas flows. The

number of revolutions of the turbo does not depend on the number

of revolutions of the engine, but instead engine power. If the engine

is supplied with more fuel, the exhaust gas flows quicker. This

causes the turbo to turn more rapidly, the charging pressure then

increases and more air is pumped into the cylinders, which allows

even more fuel to be added. This results in better combustion of

a larger amount of fuel and, with a constant cylinder volume, to

greater engine power.

Advantages and DisadvantagesA turbo offers many advantages, but why don't car manufacturers fit

turbos as standard? The advantages and disadvantages of the turbo

are outlined below.

A turbocharger offers technical and economical advantages in

relation to an engine without a turbo.

1. The weight to power ratio of a turbo engine is more favourable;

with a turbocharger it is possible to achieve relatively high power

from a relatively small engine.

2. A turbo engine offers more favourable fuel consumption, certainly

over longer distances.

3. Fuel is combusted better in a turbo engine, which leads to a

reduction on the emission of harmful substances.

4. A turbo engine makes less noise than a normally aspirated

engine; furthermore, the turbo also acts as an extra exhaust

silencer.

4. THE TURBO

4.1 Turbocharger engine flow chart

Compressed air

Intercooler

Air from airfilter

Exhaust gasses

Turbocharger

Turbineoutlet

Engine

Turbo Manual8 9

The compressor housing is designed in a way that is condusive to

compressing air, and the resulting underpressure is directed to the

combustion chamber.

The compressor housing contains the compressor wheel, fixed rigidly

onto the turbine shaft. This means that it rotates just as quickly as

the turbine wheel. The vaned rotors (or impellers) of the compressor

wheel are designed in such a way that it draws in air. The air that is

drawn in passes into the periphery of the compressor wheel and is

forced against the wall of the compressor housing. In this way the air

is compressed and then forced into the engine via the inlet manifold.

Due to the extreme speeds of rotation that characterize modern day

turbos, particularly high demands are placed on the casting of the

compressor wheel. We have seen flatback compressor wheels (photo

4.2) changing into superback compressor wheels (photo 4.3) of which

the backside has been strenghtened. The latest development is bore-

less compressor wheels (photo 4.4). This wheel is able to manage the

high rotation speeds in a better way than before.

All these measures ensure that the risk of material fatigue through

long lasting strain on the compressor wheel is yet smaller.

It is becoming increasingly common for a so-called recirculation valve

to be fitted on the compressor outlet. This valve opens automatically

if the pressure in the air inlet falls. As a result, air at the compressor

outlet is brought back to the compressor inlet. This valve ensures that

the turbo is kept up to speed as much as possible during deceleration

or braking, enabling it to be immediately available for use again as

soon as the accelerator is engaged (photo 4.5).

4.4 Boreless superback compressorwheel

5. The performance of turbo engines are better at higher altitudes.

The turbo delivers more energy because the rarefied air at higher

altitude produces less counter pressure, which allows the engine

to deliver almost the same power than is the case at lower

altitudes.einen deutlichen Vorteil.

However, the application of a turbocharger also has its disadvantages.

Advancing technological developments have already provided

solutions to some of these, and will continue to provide solutions

in the future.

1. The 'turbo lag'. The turbo only really begins to work when a

certain number of revolutions is reached. The turbo is driven by

exhaust gas and this is only released in large amounts at high

revolutions.

2. High temperature. A turbo is driven by exhaust gas which quickly

reach temperatures of 800 degrees Celsius or more. Warm air

contains less oxygen than cold air. This is also the reason why

an intercooler is often fitted between the turbo and the engine;

the intercooler cools the hot gas down to the temperature of the

air outside.

3. Extra strain. Greater power results in an increased strain on the

engine, which means that the engine, as a whole, doesn't last as

long. This disadvantage can be dealt with by always driving with

a warm engine and letting the engine cool down properly after

being stationary.

Construction and PartsA turbo is constructed from three main parts: the compressor, the

internal mechanism and the turbine.

The Compressor

The compressor housing, which is manufactured from aluminium,

and the compressor wheel are together referred to as the compressor.

The compressor's format is determined by the engine specifications.

4.2 Flatback compressor wheel

4.3 Superback compressorwheel

4. THE TURBO

4.5 Turbocharger with recirculation valve

Turbo Manual10 11

Internal mechanism

The internal mechanism forms the central section of the turbo and is

fitted between the compressor housing and the turbine housing. The

bearing housing is installed within the internal mechanism.

The bearing housing contains the rigid turbine shaft, which rotates

in a floating bearing system comprised of one or two radial bearings.

On both sides of the shaft there are vaned rotors. The rotors on the

compressor wheel are positioned in the opposite way to the rotors of

the turbine wheel. This ensures that air is drawn from the air filter.

Lubrication of the shaft and the bearings is taken care of by the engi-

ne's oil circuit. Engine oil is forced between the bearing housing and

the bearings, but also between the bearings and the shaft. Not only

does the oil act as a lubricant, it also acts as a cooling agent for the

shaft, bearings and bearings housing.

4. THE TURBO

In order to maintain a closed oil circuit, oil gaskets are located at both

the turbine and compressor ends. The suction springs that are present

at both ends should, however, not be considered true oil retaining

rings. This can be explained further as follows: an oil leak will occur

at the turbine end of the turbo if the pressure of the exhaust gas is too

low as a result of turbine damage.

The same problem can arise with the turbo compressor. If the coun-

terpressure from the engine is insufficient, the turbo will begin to leak

in the compressor end. If the turbo is then allowed to run without the

compressor outlet pipe being connected, an oil leak will occur. This

occurrence is once again an example of the fact that the suction

springs do not function as oil retaining rings.

Oil leaks in the compressor are prevented by the so-called thrust col-

lar, together with the compressor backplate and the suction spring.

The thrust collar is constructed in such a way to ensure there are no

oil leaks when the engine is idle. The backplate is the sealing plate

for the bearing housing.

Did you know that…

…a turbo, if properly maintained and lubricated,

on average will last for 120.000 kilometers? And

that you can influence is this with your driving

characteristics?

Turbo Manual1� 1�

The TurbineThe turbine is comprised of the turbine housing and the turbine

wheel. The turbine housing is made from cast iron and is therefore

resistant to the extremely high temperatures that are reached.

These temperatures can rise to more than 800 °C.

The turbo's turbine wheel is driven by exhaust gas. Exhaust gas

is fed from the engine to the turbine via the exhaust manifold. The

flow of exhaust gas automatically increases due to the gradual nar-

rowing of the channel within the turbine housing. The special spiral

design of the turbine housing ensures that the gas is fed around

the turbine wheel and ensures that the turbine turns. The turbine's

speed of rotation is determined by the passageway through the

turbine housing. The format and passageway of the turbine depend

upon cylinder volume, the number of revolutions and the desired

power of the engine.

The shaft is welded onto the turbine wheel and forms a rigid con-

nection with the compressor. At this joint the shaft is hollow, allo-

wing it to act as a thermal bridge by impeding heat transfer from

the turbine wheel to the shaft. There is a slit in the turbine end of

the shaft which contains the suction spring. The surface of the radial

bearings is extra hard and smoothly polished. The thinner tip of the

shaft passes through the compressor wheel and possesses a screw

thread and locking nut at the end to lock the wheel in place.

In most cases pressure is controlled by an excess pressure valve

that causes some exhaust gas to bypass the turbine if the pres-

sure threatens to become too high. This valve - also known as

the wastegate - is usually opened and closed by the actuator. The

actuator is mounted on the compressor cover and is connected to

the wastegate. If a turbo supplies enough pressure, the actuator will

open the wastegate. This way the turbo is prevented from supplying

too much pressure (photo 4.6 and phot 4.7).

4. THE TURBO

4.6 Closed wastegate 4.7 Open wastegate


…a turbo can fail due to an air bubble in the oil

supply? Not lubricating the turbo for a short while

can severely damage the bearing system..

Turbo Manual14 15

Due to advanced cast work, new compressor techniques and improved stress resistance of the materials utilized, the future has just begun. New technology is arriving, forming the beginning of potentially spectacular developments.

The turbo appears to be particularly suited for use with the diesel

engines of lorries. Greater power can be achieved from an engine

with a turbo, whereby the engine can remain relatively small and

the useful carrying capacity increases. This is also the reason why

from the beginning of the new millennium practically all lorry diesel

engines are equipped with a turbo. Modern diesel engines have a

wider range of revolutions, which means that high turbo pressure is

required at a low number of revolutions too.

In comparison with diesel engines, exhaust gas from petrol engines

delivers a lot of power at high revolutions and can result in extremely

high temperatures of the exhaust gas. This is the reason why petrol

engine turbos are constructed differently and are manufactured

from different types of material. A wastegate is utilized in order to

broaden the range of the turbo. The design of the wastegate also

takes the increased heat into account so that the exhaust gas is

discharged more effectively.

Sometimes diesel engine turbos look almost exactly the same as

petrol engine turbos. To prevent errors, the manufacturer Garrett has

given the different turbos a distinguishing mark (the shape of the

turbine wheel's nose differs noticeably).

6. DEVELOPMENTS THROUGH THE YEARS

The turbocharger is developing itself in several different ways. This does not only apply to the turbocharger but is also true for all products that are used in combination with turbos. Furthermore turbo manufacturers are developing the techniques of using more than one turbocharger in a passenger car.

The IntercoolerA turbo operates with compressed air. The process of compressing

air generates heat, which in turn reduces the oxygen level present.

This is not beneficial for achieving optimal combustion since this

requires as much oxygen as possible in the compressed air. The

compressed air therefore has to be cooled, and as a result, a sort of

radiator - the intercooler - is fitted between the turbo and engine.

The intercooler cools the air down again.

Parallel Twin-Turbo SystemIt is possible to build in more than one turbo. V-type engines in

particular offer a choice of several smaller turbos. Smaller turbos

get going quicker and thus respond sooner to the acceleration

pedal. In addition, two smaller turbos produce a quicker result than

one large turbo. There are also a few (small) disadvantages: two

turbos are usually more expensive than one large turbo, and the

synchronization requires precision. A good example of a passenger

car using two smaller turbos is the old Nissan 300 ZX.

Serial Twin-Turbo SystemTurbos can be connected in series as well as in parallel. Turbos are

positioned in one line, producing an amplification effect. Exhaust

gas first enter the turbine of the high pressure turbo and then the

turbine of the low pressure turbo. The gas arrives at the outlet after

having passed through the two turbos.

The serial twin-turbo principle was tested by BMW in 2004 in the

exhausting Dakar Rally. The Variable Twin Turbo (VTT) technology

operates in a two-step system - or sequential pressure charging. A

small turbo begins, but at the right moment, the supply of air to the

engine is taken over by a large turbo. With its new 3 litre VTT diesel

engine, BMW was able to achieve 20% more power, greater torque

at lower revolutions and a wider range of revolutions (photo 5.1).

5. ADDITIONAL COMPONENTS

5.1 BMW serial twin-turbo system


…the average exhaust gas temperature lies around

800 degrees Celsius with modern diesel engines?

And with petrol engines this temperature exceeds

1000 degrees?

Turbo Manual16 17

Technology Variable technology was first applied commercially in 1989 by

Garrett. This caused a revolution in the diesel engine turbo market

for passenger cars.

Following the first VNT turbochargers (or Variable Nozzle Turbine)a

second model was introduced. The subsequent design is charcterized

by more vanes and, due to a large traction force from low revolutions,

is currently the standard for passenger cars with diesel engines.

The size of the turbine housing passageway can be adjusted to

the maximum speed and tractive force required by the engine. To

solve the problem of reduced performance at the engine's lower

range, a smaller exhaust gas passageway is required. To achieve

this the turbine housing comprises a number of moveable vanes. If

the passageway between the vanes is made smaller, the pressure

produced by the exhaust gas is still high. Furthermore, by adjusting

the vanes the angle at which the exhaust gas approaches the

turbine wheel can be changed.

When the vanes are in an almost closed position, exhaust gas is

directed towards the tip of the turbine vanes, which allows the turbo

to accelerate quickly and produce a higher turbo pressure, as if it

were a turbo with a small exhaust gas passageway (photo 6.3).

When the turbo pressure then builds up, the vanes are opened, thus

curbing the turbo's acceleration. If the vanes are in the maximum

open position, it is as if no variable nozzle ring has been fitted

and the maximum number of revolutions of the turbo is again

determined by the actual exhaust gas passageway of the turbo's

turbine housing (photo 6.4.)

6.4 Vanes opened: maximum turbine speed

6.3 Vanes closed: enhanced turbine speed

These days the car industry has to fulfil very heavy demands: cleaner,

safer, more economical, more powerful and more comfortable. With

ever stricter emission standards and the demand for smaller but

more powerful engines, it would appear that turbochargers have an

essential role to play, in particular with regards to diesel engines.

Optimalization of mechanics and electronics is increasing the

yield of the modern diesel engine further and further. An additional

advantage is that the ever stricter emission standards can be met.

The future standards will be barely achievable for engines with the

same cylinder volume as current models. The use of the turbo can

offer help.

Turbo ElectronicsNowadays there are heavier demands on fuel usage, emission

standards and noise levels. In order to meet these demands a

solution needs to be found using electronics. Small computers

continuously record all data and calculate the optimal turbo

pressure for each number of revolutions. The serial application of an

electronic actuator - which makes the turbo react quicker - is also a

development that should not be left unmentioned (photo 6.1).

Variable Turbine TechnologyOne of the limitations of a turbocharger is the passageway for

exhaust gas in the turbine housing. When a turbine housing with

a small passageway is used, the turbo will perform well at low

revolutions. Low revolutions deliver a flow of exhaust gas with a low

pressure. However, this air flow is forced together through the small

passageway, giving rise to high pressure.

The disadvantage of a turbo with a small passageway is that it

quickly reaches its maximum power. In the case of an exhaust

housing with a large passageway for exhaust gas, this problem is

turned around. The turbo performs well at the higher range of the

engine, but will produce too little turbo pressure at lower revolutions.

In order to solve this dilemma, the size of the passageway can be

varied, thus making optimal use of a large and small passageway.

This is made possible using a variable passageway, or the so-called

variable geometry (photo 6.2).


6.1 Electronic acutator

6.2 VNT Turbocharger

Turbo Manual18 19


The VNTOPGarrett also developed the VNTOP, which stands for 'VNT one piece'.

This is also sometimes referred to as a turbo with 'slide vane' and

is a simplified technical model of the variable turbo. With this type

of turbo the vanes cannot be individually regulated, but instead a

slidable ring determines the flow towards the vanes (photo 6.6 and

photo 6.7). This is a more compact, cheaper and simpler type of

turbo with less precise adjustment options. The VNTOP is widely

used with diesel engines in the small and medium-sized passenger

car classes.

6.6 Turbine inlet fully opened

6.7 Turbine inlet fully closed


…modern turbos achieve speeds of more than

220 000 revolutions per minute? And that airplane

rotors only achieve 7000 revolutions per minute?

Turbo Manual�0 �1

7.1 Blue discoloration 7.3 Damaged bearing seating

7.2 Jammed radial bearings 7.4 Broken shaft

No matter how good a turbo is developed and maintained, damage is always a possibility. And because not every damage is the same, we can say that each problem ha sits own solution as well. This chapter covers all these possibilities, and the main objective lies in discovering the cause of alle problems.

Turbo Damage The turbo is experienced by most garages as a complicated part. That

isn't really any great wonder considering that during the course of

time the turbo has become increasingly more compact, the number

of revolutions have increased considerably to more than 200 000

revolutions per minute and the turbine is taking an increasing greater

part in engine management. Although the complexity is actually quite

reasonable, the turbo is and remains a sensitive component. Fortunately

turbo damage doesn't occur as often as it did in the beginning. The

damage that does arise often falls into the category of consequential

damage. The cause is not immediately known, but the consequence

- a defective turbo - is.

To Replace Or Not To Replace?Simply replacing a defective turbo with a new or reconditioned unit is

only a short-term solution. It is advisable to ascertain whether the turbo

is the cause of the complaint and, for that matter, the only cause. A turbo

should be replaced once all possible options have been investigated

in the workshop and the turbo is thus confirmed as being defective.

The summary given below can provide useful assistance in tracing,

recognizing and solving the cause of turbo problems.

Determining the Cause of ComplaintsProviding an engine runs properly and is well maintained, a turbo

should function reliably for years. Many turbos are needlessly replaced

because the correct diagnosis is not established. Even if it is decided to

replace the turbo, it is still important to determine why the defect was

caused so that comparable problems can be prevented in the future.

The defects that can arise with turbos, as well as their causes, are

described here.

Insufficient Lubrication

Insufficient lubrication allows heat from the turbine wheel to be

transferred directly, causing the remaining lubricant to burn or char,

resulting in colouration of the shaft (photo 7.1).

The bearings become jammed and damaged (photo 7.2). As a result

further damage can arise: wheels rubbing against the housing

(photo 7.3), oil gaskets giving in or the shaft possibly breaking

(photo 7.4).

7. TURBO DAMAGE


…repairing a turbo takes up more than 5 hours of

labour per turbo? And the time we need to machine

all parts takes up over 4 hours?

Turbo Manual��

Since the high temperature spreads the bearing assembly also

become very hot. This causes it to expand, and material from the

bearings can therefore be deposited on the shaft (photo 7.5).

The movement of the shaft has caused considerable wear on the

outside of the gasket box. The bearing surface of the thrust collar is

worn away (photo 7.6).

7. TURBO DAMAGE

7.6 Damaged thrust collar

7.5 Shaft with bearing damage on turbine end 7.7 Damaged thrust bearing


…a turbo can accelerate in less than one second

from 20.000 revolutions up to 150.000 revolutions

per minute?

The material of the outermost axial bearing has been melted away

by the high heat of friction between the thrust collar and axial

bearing (photo 7.7).


Impact from ObjectsMajor damage to the turbo can arise due to the impact with foreign

objects (photo 7.12). The variable section is also sensitive to impact

damage, with the nozzle ring being particularly prone (photo 7.13). The

attached pictures show what the consequences of impact with loose

objects from the engine can be.

7.12 Damaged turbine wheel

7.13 Damaged nozzle ring

The vanes of the compressor wheel also rub against the wall of the

compressor housing (photo 7.8, photo 7.9 and photo 7.10). The tip

of the vanes are deformed and partly shorn off. The severe forces

involved may even break the bearings or shaft (photo 7.11).

7. TURBO DAMAGE

7.8 Damaged compressor wheel

7.9 Damaged and new compressor cover

7.10 Compressor cover showing signs of wheel damage

7.11 New and broken radial bearing


A hard object enters along the compressor inlet. The vanes of the

compressor wheel are damaged or have disappeared completely

(photo 7.14). With the entry of a soft object less damage is caused,

but the vanes can nevertheless be bent backwards.

A leakage between the air filter and the turbo can cause small dirt

particles to enter, and because of the abrasive action the compres-

sor wheel then becomes damaged (photo 7.15). This can put the

shaft and the wheels out of balance and cause them to become

unstable. The extremely high number of revolutions means that

further damage is unavoidable.

7.15 Compressor wheel damage due to airfilter problems

7.14 Compressor wheel damage due to large foreign object

7. TURBO DAMAGE


…it is wise to let an engine cool down after a drive,

in order to lubricate the turbo? The turbo otherwise

still be spinning at high revolutions without proper

lubrication.


7.18 Damaged bearing housing

Fouling of the engine oil

The oil in the turbo has a dual purpose: lubrication and cooling. The

attached pictures demonstrate what can happen if the engine oil

becomes contaminated with dirt.

Filtered engine oil can still contain small particles of dirt. The

bearing surface of the shaft is normally very smooth, but the

remnants of dirt in the oil have ground deep scratches into it. Dirt in

the oil has a abrasive action (photo 7.16). This can be clearly seen

on the bearing surface of the axial bearing. At several places this

surface is completely worn away, leading to the oil channels being

clogged (photo 7.18).

Due to the abrasive action of the contaminated engine oil, both sides

of the thrust collar are worn out (photo 7.17).

7. TURBO DAMAGE

7.16 Radial bearing damaged due to dirt in oil

7.17 Damaged thrust collarDid you know that…

…a turbocharger which has unbalance can cause

a irritating sound and diminishes the lifecycle

expectancy of a turbo?


Excessive counterpressure from the exhaust gas

In most cases, the cause of excessive counterpressure from the

exhaust gas is a blocked outlet. Excessive counterpressure can also

be caused by problems with the catalytic converter or, in modern

engines, the EGR-valve.

The attached pictures clearly show what the consequences of this

can be.

There is wear and tear of the suction spring and the suction spring slit

of the shaft, with a resulting oil leak in the turbine side (photo 7.22).

The oil in the turbine is charred (coked), and as a result coke particles

can be found in the bearing housing.

7.22 Turbine shaft with burned oil deposits

Fouling can also include charring (or coking) of the engine oil (photo

7.19). Charred oil can stick to the inside of the bearing housing

and block the oil gaskets. This can possibly lead to oil leak. The

charring of oil can also result in further damage to the bearings

and gaskets.

If the lubricant is very dirty, deep scratches can be made in the

bearing points of the turbine shaft (photo 7.20). In the case of

aluminium bearings, dirt will often stick to their surfaces and thus

cause great damage to the bearing surfaces of the shaft and bearing

housing (photo 7.21).

7. TURBO DAMAGE

7.19 Damaged bearing housing 7.20 Shaft damaged by dirt in lubrication

7.21 Blue discoloration


…a passenger car can produce blue smoke whilst

standing in front of traffic lights? And that this is an

important signal for a turbocharger problem?

Turbo Manual��

Material FatigueMaterial fatigue arises due to prolonged or excessive strain on the

materials used. The possible consequences of this are shown in the

attached pictures.

Material fatigue of the compressor wheel can occur if a vane breaks

off from the wheel, even though there may be little or no visible

traces of rubbing or impact from foreign objects (photo 7.24).

Material fatigue can also cause the speed of rotation to become

too high and/or prolonged exceedance of the maximum speed of

rotation, which in turn can cause the compressor wheel to explode

at the weakest point (photo 7.25).

7.24 Compressor wheel damage due to foreign objects

7.25 Compressor wheel damage due to material fatigue

Excessive exhaust gas temperature

The most commonly occurring causes of an excessive exhaust gas

temperature with diesel engines are a defective or blocked inter-

cooler, an incorrectly adjusted fuel pump or a blocked air filter. The

attached pictures show what can happen if the temperature of the

exhaust gas gets too high.

Formation of cracks

High temperatures can lead to cracks in the turbine housing, which

as a result cause exhaust gas to leak. This means that there is

reduced drive for the turbo's turbine and ultimately decreased turbo

pressure (photo 7.23).

After a while practically all turbine housings of turbos, regardless

of make or application, show contraction cracks. These occur

especially quickly in engines with a relatively high strain and

most petrol engine applications in passenger cars. In many cases

cracks or other types of damage to the turbine housing can have a

detrimental influence on the operation of the turbo.

7. TURBO DAMAGE

7.23 Damaged turbine housing


…only badly balanced or worn out turbos cause

excessive sounds? And that a well maintained

and functioning turbo can hardly be heared?


3. Problem: black exhaust gas.Possible cause:defective turbo. Solution:repair/replace turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:air leak between turbo and inlet manifold.Solution:replacement of turbo is not necessary; check the connection and replace components

Possible cause:exhaust gas leak from the turbo.Solution:consider replacement of turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:problem with fuel system.Solution:replacement of turbo is not necessary; readjust and check fuel system.

Possible cause:internal engine problems.Solution:consider replacement of turbo; telephone +31-(0)33-2570607 for more information.

8. PROBLEMS AND SOLUTIONS

Turbo World T +�1 (0)�� 57 06 07 Turbo World T +�1 (0)�� 57 06 07

Turbo problem analysis 1. Problem: the engine holds back during acceleration.Possible cause:turbo's excess pressure system is defective. Solution:repair/replace the turbo; telephone +31-(0)33-2570607 for more information.

2. Problem: the engine delivers too little power.Possible cause:defective turbo.Solution:repair/replace the turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:air leak between turbo and inlet manifold. Solution:replacement of turbo is not necessary; check the connection and replace components.

Possible cause:exhaust gas leak from the turbo.Solution:consider replacement of turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:problem with fuel system.Solution:replacement of turbo is not necessary; readjust and check fuel system.


Possible cause:incorrect adjustment of the ignition timing.Solution:replacement of the turbo is not necessary; readjust the ignition timing and renew defective components.

Possible cause:turbo's excess pressure system defective.Solution:repair/replace turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:obstruction between the turbo and the inlet manifold.Solution:replacement of the turbo is not necessary; remove the obstructions and renew the defective components.

Possible cause:obstruction between the turbo and the exhaust manifold. Solution:replacement of the turbo is not necessary; remove the obstructions and renew the defective components.

Possible cause:incorrect adjustment of the ignition timing. Solution:replacement of the turbo is not necessary; readjust the ignition timing and renew defective components.

Possible cause:obstruction between the turbo and the inlet manifold.Solution:replacement of the turbo is not necessary; remove the obstructions and renew the defective components.

Problem: excessive use of engine oil.Possible cause:excessive use of engine oil.Solution:defective turbo. Solution: repair/replace turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:air leak between turbo and inlet manifold.Solution:replacement of turbo is not necessary; check the connection and replace components.

Possible cause:internal engine problems.Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.


8. PROBLEMS AND SOLUTIONS

Turbo World T +�1 (0)�� 57 06 07 Turbo World T +�1 (0)�� 57 06 07

Possible cause:obstruction between turbo and inlet manifold. Solution:replacement of the turbo is not necessary; remove the obstructions and renew the defective components

Possible cause:obstruction between turbo and exhaust manifold.Solution:replacement of the turbo is not necessary; remove the obstructions and renew the defective components.

7. Problem: oil leak in the air inlet side of the turbo.Possible cause:defective turbo.Solution:repair/replace turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:exhaust gas leak from the turbo.Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.


Possible cause:oil discharge or sump ventilation blocked. Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:obstruction between turbo and exhaust manifold. Solution:replacement of the turbo is not necessary; remove the obstructions and renew the defective components.

5. Problem: blue exhaust gas.Possible cause:defective turbo.Solution:repair/replace the turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:air leak between turbo and inlet manifold.Solution:replacement of turbo is not necessary; check the connection and replace components.


Possible cause:oil discharge or sump ventilation blocked.

Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.


6. Problem: turbocharger makes a lot of noise.Possible cause:air leak between the air filter and the turbo.Solution:replacement of turbo is not necessary; check the connection and replace components.

Possible cause:defective turbo.Solution:repair/replace turbo; telephone +31-(0)33-2570607 for more information

Possible cause:air leak between the turbo and the inlet manifold.Solution:replacement of the turbo is not necessary; check the connection and replace components.

Possible cause:exhaust gas leak from the turbo.Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.

Possible cause:oil discharge or sump ventilation blocked.Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.


8. Problem: oil leak in the turbine side of the turbo.Possible cause:defective turbo.Solution:repair/replace turbo; telephone +31-(0)33-2570607 for more information.


Possible cause:oil discharge or sump ventilation blocked.Solution:consider replacement of the turbo; telephone +31-(0)33-2570607 for more information.


9. QUALITY CHECkLIST

The following checklist can be used once the cause of a defective turbo is known and the decision to replace it has been made. Should there be something wrong in the proximity of the turbo, this should come to light with the installation directions below.

1 Check the oil supply pipe

Dismantle and check the oil supply pipe. Clean the pipe. If any form

of blockage is established, the oil supply should be immediately

replaced. Check for kinks in the pipe as well. Make sure that liquid

gaskets are never used.

� Refresh the oil

Don't forget to renew the engine oil and oil filter. If this is not done

on time the turbo may be damaged. Old or dirty oil hinders lubrica-

tion of the internal mechanism and therefore causes damage of the

bearings and shaft.

� Check the oil discharge pipe

Dismantle and check the oil discharge pipe. Clean the pipe. If any

form of blockage is established, the oil discharge should be imme-

diately replaced. Check for kinks in the pipe as well. Make sure that

liquid gaskets are never used.

4 Check ventilation of the oil sump and condition of the engine

If the engine is in poor condition, pressure can build up in the oil

sump. This means that oil vapours are formed, and these vapours

are released via the sump ventilation (or crankcase breather). In

many cases the sump ventilation is connected to the turbo's air sup-

ply pipe. The turbo blows these vapours towards the engine, causing

incomplete combustion to occur. Check the pressure in the oil sump

and the sump ventilation. Furthermore, blocked sump ventilation

causes oil discharge problems for the turbo.

5 Check the air pipes Always fit a new air filter and clean the air suction hose. If an

intercooler is fitted, oil residues may have to be removed. The hose

from the turbo to the engine has to be checked carefully. The inlet

manifold also has to be checked for possible residues from the

previous turbo damage.

Turbo Manual40 41

9. QUALITY CHECkLIST

6 Check the oil pressure

Use a clean trough to collect the oil from the oil discharge pipe.

Ensure that the oil circuit is filled without the engine running. This is

sufficient to allow any possible dirt or soot residues to be extracted

via the pipe and therefore ensure that the turbo's bearings are not

damaged.

7 Attachment on the manifold

The exhaust manifold may still contain remnants of metal from the

previous turbo damage. This must be removed. A cracked manifold

can damage the new turbo. Check this carefully.

8 Remove all stopcaps

Stopcaps have been fitted in the turbo so that no foreign objects can

get into it during transmittance. The caps should all be removed,

with the most important being the oil supply plug.

9 Check the oil supply

Fill the turbo with oil. Install the oil supply and ensure that no dirt

can enter the turbo's bearing housing. Run the engine for one

minute without starting the turbo. Then let the engine run idle for

five to ten minutes.

10 Check the connections

Gradually increase the number of revolutions of the engine during

testing and check all connections for possible leaks. All bolt

connections should be verified when the engine is warm.

11 Check the turbo pressure

The turbo pressure should be checked using a turbo pressure meter,

available in Turbo World's assortment. Adjustment of the actuator is

done at the Turbo World workshop in advance.

Turbo Manual4� 4�

The cleaning ProcessOn arrival the turbo is dismantled and analysed. The components are

then cleaned thoroughly. A special washing machine and an industrial

oven are used for this. This cleaning process improves the quality

of components such as the bearing housing and turbine shafts. The

reason for this lies in the fact that less intensive use of the following

process, surface treatment, is required. This process can cause

the measurements of components to change, which can in turn lead

to problems

The surface treatment processCast iron components are blasted automatically with a strong particle

blaster. Another blasting machine is used for aluminium parts which

works using a ceramic glass bead (photo 10.2). The bearing housing

receives yet further treatment in the form of an ultrasonic cleaning bath

to ensure that no dirt is left behind. Finally, all components are greased

in order to prevent corrosion. They are then transferred to the next

process in our advanced workshop.

10.2 Sand blasting

10.1 Washing machine

Turbo World delivers reconditioned turbochargers for every type of engine. The workshop possesses four specialized disciplines: cleaning, surface treatment, control and balancing. These four specialities ensure that the reconditioned turbocharger equals or even exceeds the quality of a new turbo.

After all, during factory production components are manufactured

in series within fixed margins and tolerances, without specific

attention being given to each separate component. This does

not apply during the reconditioning of a turbo. The tolerances of

each component are checked with high precision. A reconditioned

turbocharger therefore satisfies the ideal factory specifications

better than a serial product.

10. IN THE WORkSHOP


…an engine in bad condition can be the cause of

a rising oil pressure in a turbo? And that this will

definately lead to oil leakage from the turbo?


…changing the original characteristics of a turbo

leads to a shortened lifecycle of a turbo? Driving

with excessive turbo pressure will eventually lead

to bearing damage.

Turbo Manual44 45

final inspection before the turbo is fitted onto the engine. For this we

use a Vibration Sorting Rig (photo 10.6), a machine made compulsory

by large turbo manufacturers.

If the turbo comes through the final inspection it is well and truly

in order. The most precise balancing processes in particular ensure

that no single detail is left uncovered. After the balancing process we

measure the play on the bearings and compare this value with the

original manufacturers tolerances. Finally the turbochargers actuator

is set against original manufacturers values as well.

10.6 Vibration Sorting Rig machine

10.5 Core balancing machine

The control processThe turbine shaft is checked for straightness before it can be

installed into the internal mechanism of a turbo. To do this, Turbo

World uses a straightness meter. The bearing points of the turbine

shaft and the bearing housing are remeasured using hand tools to

check that they indeed fall within the permitted tolerances. After

balancing, the space around the bearings in the internal mechanism

is checked and verified using manufacturer's data. Work on the

turbo is then completed. The final step is to adjust the actuator

according to factory specification (photo 10.3).

The Balancing ProcessBefore a turbo arrives at the garage where it is to be fitted into the

car, it has already undergone various treatments. Balancing is one

of the most important parts of turbo reconditioning. The reason for

this is simple, considering the number of revolutions that a modern

turbo can achieve (more than 230 000 revolutions per minute). Any

imbalance in these revolutions will, either immediately or later, lead to

major damage inside the turbocharger.

Before balancing a turbo it is very important to carry out a proper

dynamic balancing of the wheels. That is: with two correction

surfaces. Each component is balanced separately.

For this we use a Schenck balancing machine (photo 10.4). The

components are then installed in such a way that the turbo becomes

one complete working unit. Since the added components are

not all individually balanced, the rotating section of the turbo is

balanced once again as a whole. We use an internal mechanism

balancing machine for this (photo 10.5). The last step is to check the

turbochargers for possible vibrations at revolutions expected from

engines. Such vibrations can lead to excessive noise. This is an ideal

10. IN THE WORkSHOP

10.3 Measuring tolerances before balancing

10.4 Schenck rotor balancing machine

Turbo Manual46 47

11. DO THE TURBO TEST

Multiple Choice Test Question 1. How does a turbo work?

A. Injection of extra fuel causes a turbine effect, which causes the engine to run better.

B. The supply of extra air and fuel results in increased engine power.

C. The supply of compressed air ensures better combustion and greater power.

D. The turbine wheel "mixes" the air and fuel, resulting in better combustion.

Question 2. When did the first turbo appear?

A. Just before the beginning of the 20th Century, before 1900.B. Between the two world wars, with the rise of the petrol engine.C. Immediately after the Second World War.D. In the fifties, partly as a result the increasing popularity of

Formula 1 motor racing.

Question 3. Name four advantages of a turbo compressor.

A. Greater engine power, a more effective combustion process, lower emission, a more beneficial weight/power ratio.

B. Greater engine power, less wear and tear of the engine, lower emission, a more beneficial weight/power ratio.

C. Greater engine power at high revolutions, a more effective combustion process, lower emission, a more beneficial weight/power ratio.

D. Greater engine power at low revolutions, a more effective combustion process, lower emission, a more beneficial weight/power ratio.

Question 4. How is air from the turbo cooled?

A. With the lower temperature of the outside air.B. With lubricant.C. With an intercooler.D. Answers B and C are both correct.

Question 5. Why do the cooling fluid pump and oil pump usually continue to work for a short while after an engine with a turbo is switched off?

A. Answers B and D are both correct.B. The lubrication still present protects the bearings.C. This is necessary to pump the pipes empty.D. To discharge heat from the turbo and to prevent material stress

Question 6. Name three measures to avoid damage of the turbo bearings.

A. Don't accelerate immediately after a cold start so that oil can be supplied and metal contact prevented.

B. Don't switch the engine off immediately after a long or deman-ding journey, otherwise oil pressure is lost and wear and tear due to metal contact can occur.

C. Let the engine run idle for a while so that the turbine housing can temper and the engine oil is less thermally stressed to prevent charring (or coking).

D. Regularly – preferably once a month – undertake maintenance with suitable oil.

Question 7. What is understood by the "turbo lag"?

A. The diameter of the internal mechanism (or central hub rotating assembly) of the bearing housing.

B. The phenomenon that a turbo really begins to work at a certain number of revolutions.

C. The space under the bonnet where the turbo should be placed.D. The limits of the modification possibilities for increasing a turbo

oneself.

The world of the turbo48

Answers

1c 2a 3a 4c 5d 6b 7b

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Turbo Manual