Saab 900 Engineering features 1979 [OCR]

8/10/2019 Saab 900 Engineering features 1979 [OCR]

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onte nts

he S aa b app roach - a ph i lo sophy wi th an e ye to the fu tu re 2

Correct ly con ceived and p ro p erly built 4

A stre amlin ed b o d y d e sign s aves fuel 6

he ex ter io r in its en t i r e ty an d in detail 8

he S aab safety cage I 0

Safet y of the occ upan ts 2

O n e o f the most co m fo r t ab l e in te riors in an y car. an ywhere 4

h e dr iver s s eat - a w o rk p l ace 6

D river s e nvironm ent 8

Heat ing and v entilation 20

o see and to be seen 22

Self-rep airing bumpe rs 24

E n g in e an d gear box 26

S aab urbo - th e car of the fu tu r e 30

R o ad beav io r 34

R o ad ho ld ing in theor y and prac tice 8

h e so r t of s afety marg in a l l cars s ho u ld h av e 4

L uggage and s to w age spaces 44

Techn ical s pecifi cations 46


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Saab 91979 model rangeSaab 9 GLi3 doors

Saab 9 MS3 doors

Saab 9 GLE5 doors

Saab 9 Turbo

3 doors

Saab 9 Turbo5 doors

2-litre fuel-injected engine developing I 15 hp 85 kW)

SAE net I I 0 hp . 81 kW . catalyst equipped) Manual orautomatic transmission.

2-litre fuel-injected engine developing 115 hp 85 kW)SAE net 110 hp. 81 kW . catalyst equipped) . Manual orautomatic transmissi o n.

2-litre fuel-injected engine developing 115 hp 85 kW)SAE net I I 0 hp. 81 kW. catalyst equipped). Manual orautomatic transmission.

2-litre fuel-injected and turbo charged enginedeveloping 135 hp IOO kW) SAE net. Manualtransmission.

2-litre fuel-injected and turbo charged enginedeveloping 135 hp I 00 kW) SAE net. Manualtransmission .


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ome re w rds of inno vationsand new a pproach . .

G r e a t Britain

T he Don S afety Tro phy in 19 72

U S A

Fina list in the nominatio n for the t itle of C ar ofth e Year a mong im p or ted br a nds n 19 7 6(S aab 99 E MS) and 1 977 (Saa b 99 Turb o)

G e r m a ny

Oscar for car sa f e ty(Hobby )

Au s tria

Overa ll winner in Com p uter test1975 (Das K Lirier)

Denm ark

Outr ight winn er in compara t ive test in 1977(Bilen )

Sw e den

G o ld medal f or car saf ety in 1 97 2(T h e Swedis h Automo bile Assoc iation)Ca r oftheYearin 1972 (Tekn ikens Varl d)

O verall win ner in N ordtest ' ' i n 1972 an d 1973(Vi Bilagare)

Golde n Gear n 1978 fo r the de v elopment ofthe S aab Turb o(V eckans A ffarer and Ekonom isk F6reta gsled-ning)


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streamlined body design saves fuelTests on cars qf he same size and performanc e class as the Saab 900 show thatthe.fuel consumption of he car in normal everyday u se can be reduced by about10 by lowering the drag coefficien t (i.e. the air resistance coefficient) from 0 5to 0.4. The drag coefficient can be regarded as a sort of quality.factor for the ex -ternal.form qfthe car.

On the other hand, the lowest possible air resistance (drag) s not the only aim.Consideration must also be given to the influence of orm optimization on theroad behaviour and directional stability qf he c r in gusty cross-winds, forinstance. t high speeds, the air.flowing over the body qfa car may give rise to

an appreciable lifiing.force on the rear wheels which reduces the road grip.Other areas which must be studied include the ventilation and air conditioning,fouling of the windows, the size and location of the cooling air intake, formationo f vortices and the dispersion o f he exhaust gases behind the car.

DRAG AND POWER DEMAND

The drag coefficient is often used as a sort ofquality factor for the form ofa car body. Thedrag coefficient is relatively independent of thesize of the car and is between 0.32 and 0.50 onmodern cars. The lower the coefficient. themore favourable is the shape.

An interesting observation is that the frontalarea of present-day European cars varies verylittle (the s catter is 4 l. although the aerodynamic differences are many times greater. Theaverage drag of current European cars is about0 .46 and that of modern mass-produced cars

for everyday use is hardly below 0.40. On theother hand. the scatter is more than JO ) , .

A series of full-scale wind tunnel tests hasenabled Saab designers to adjust gradually thebasic design of the 900 body by minor detailmodifications towards its final optimisedform. The final result was a compromisewhich accommodates most of the demands oncomfort. safety. appearance and low drag.

The drag on a car is dependent on a number offactors - form of the body and its projectedfrontal area . its speed and the atmosphericconditions .

Formula : Wwc,,.F

c \ x F x __ x v F 22

Drag

Drag coefficientProjected front area of thevehicleDensity of airSpeed of the vehicle

The power demand is fairly low as long as thespeed of the vehicle is moderate and there isno wind. At 45 mph (70 km / hl. for instance.the drag of a normal medium-size car may beof the order of 150 - 200 N. and the corresponding power demand will be J - 4 kWabout 5 hpl. But at a road speed of 60 mph

(I 00 km / hl. the engine must supply a further7 - 8 kW I 0 hp) or thereabouts to the drivenwheels in order to overcome the drag. At 93mph ( 150 km / hl. the engine must develop 35- 40 kW or 50 expensive horsepower(27 times as much as at a third of this speed or8 times as much as at half the speed).

The relationship is clear: if a given speed isdoubled . the drag will be increa sed by 2 2 = 4times . if the road speed is tripled. the drag willincrease by J 2 = 9 times . etc.6

The power demand increases even more steeply. rising as the cube of the speed instead of thesquare 2 3 = 8. 3 3 = 27. 4 3 = 64 , etc.). Ifthepower demand at 20 mph 0 2 km / h) is 0.5 kWthe power demand at 80 mph I JO km / h) willbe0.5 x 4 3 = 32 kW.Head winds and. to an even greater extent.cross-winds naturally increase the powerdemand and the fuel consumption. Measurements have shown that when a car is driven at70 mph I I 0 km / h) in a strong cross-wind.the engine must develop an extra I 0 - 15 kWI J - 20 hp) and will consume about 5 litresI .3 US gallons) more fuel per 60 milesI 00 km) as compared to calm conditions.

Since far from all of the engine output reachesthe driven wheels - transmission lossesabsorb some of the power - a very largeproportion of the engine output is used up forovercoming the drag at high road speeds.

A -OW DRAG IS MERELY ONE ASPECT

The first aerodynamic test on the Saab 99 in1964 revealed that the drag coefficient was aslow as 0.36. A I :5 scale model was used forthe test. But the 99 has since undergone certain modifications . such as being fitted withnew bumpers. and the present-day Saab 99Sedan therefore has a higher drag coefficientthan the original model.

But the lowest possible drag is not the onl y

consideration. The ventilation. the dispersionof the exhaust gases behind the car and manyother factors must also be taken into account.When Saab designed the hatchback model ,one of the aims. for instance , was to ensurethat the rear window will be self-cleaning .Tests under the worst conceivable roadconditions revealed that the results achievedexceeded all expectations. The air flowsdownwards along the window. without givingrise to appreciabl e vacuum. The air can besaid to form a curtain between the glass andairborne dirt.

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MORE FAVOURABLE SHAPE

The factors which a car designer can affect arethe shape and size of the car body. The factthat the Saab 900 is far larger inside than itsexterior would suggest is a tribute to the competence of Saab designers. The remainingfactor is, thus. the shape of the car.

Wind tunnel tests on full-scale cars prove thatthe Saab 900 has an even lower drag coefficient than the corresponding 99 models. TheSaab 900 has been designed and styled foroptimum directional stability under all conditions - even in gusty cross-winds. The designof the rear window and the luggage compartment lid and the transition between the sidesurfaces and the rear sections are all of vitalimportance to the exceptionally good directio

nal stability in windy weather. The deeplycurved windscreen and the absence of sharpcorners which often cause turbulence contribute to the exceptionally low wind noise inthe car.

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LOW WIND NOISE

A sun roof is fitted on certain models andmarkets. The wind noise caused by the Saabsun roof is exceptionally low - even at highspeeds. This is due to the curved windscreendeflecting part of the air to the sides instead ofupwards and to the ideal design of thetransverse ridge forward of the sun roof.Many competing cars are not provided withthis ridge and the separate wind deflecto r fittedinstead often merely causes more wind noise .

SPOILER AT THE FRONT AND REAR

Years ago many car manufacturers startedexperimenting with spoilers fitted at the frontand rear of their competition cars. in order toincrease the top speed and improve the roadbehaviour at high speeds. The spin-off oneveryday cars can be seen today. On theSaab 900 , the front spoiler is integrated intothe body. The spoiler reduc es the fuelconsumption and increases the directionalstability at high speeds. The 3-door Turbo is

also fitted with a spoiler at the rear.The front spoiler is made of black thermoplastic rubber . which is resistant to flying chipsand low temperatures. and is pliable and resilient. The spoiler will normally deflect withoutbeing damaged if it should strike an obstruction at low speed. So the ample ground clearance is not affected in practice.


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oc --- ...--Weak sensation Normal heat T r rf heat

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t---hermostat switches offI I

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rI I:::; Weak sensationo of heatQj minutesc _

EOS: len minutes 0 2 3 4 5 6 7 8 9 1 11 12 13 14 15

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E MS Turbo M S GL E Turbo

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fo r e

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tim e


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MBDA EMISSION CONTROL

b 900 cars for sa le in the Western andky Mountain states and all 900 Turbo 's are

ipped with a new Lambda Control systema threewa y catalyst. This is a dramatic de

ure fr o m other ca talyst systems.

roblem with most catalysts currently usedhat th ey only work to ox idize the carbon

oxide (CO) and the unburned hydrocars (HC) thanks to exess oxygen in exhaust.

oxygen is present either from a lean mixor through secondary air being injected

the exhaust stream before it reaches theal ys t. The exess oxygen. however . does not

k e it possible to eleminate the pollutant. nius oxides (NO) . To remove NO, catalytiy . a deficiency of oxygen is required. t

seems that it qould be impos s ible to ree all three pollutants. CO. HC and NO,ugh one catalyst.

there is one pos s ibility. Within a very narran ge o f air-to-fuel ratios the oxidizing re

ons for CO and HC and the reducing reacs for NO, overlap. This narrow range is

metime s called th e three component winw

de s ign goal is to control the engine's airuel ratio so precisely during all engine opeons so that it remains within thi s win

. or the stoichiometric v a l u e a n air

ucl ratio of 14.5: I. (The symbol Lambdaally indicate s multiples of 14.5: I) .

Saab Lambda Control system consists ofbasic components. which work together

ollows:An oxygen sensor which is mounted in theaust manifold and which continuouslyses the oxygen content of the exhaust.An electronic control unit which receives ainuous signal from the oxygen sensor and

n sends a signal to:A modulating valve which contiuously ads the pressure in the fuel distributor to main the proper air-to-fuel ratio at al l times .A full-throttle enrichment switch which

override the oxyge n sensor during fullottle acceleration.The three-way catalyst which at the properto-fuel ratio oxidizes hydrocarbones andon monoxide and at the same time takes

gen away from oxides of nitrogen . Tracesplatinum and rhodium are used in the catac material.

ELECTRICAL SYSTEM

The electrical distribution box is located on theleft-hand side of the engine compartment. Thecables to the interior of the car are not run inthe conventional manner through a hole in thebulkhead. On the Saab 900. three multi-poleconnectors arc used instead. and this providesbetter protection against corrosion. dirt andmechanical damage . The electrical distributionbox can accommodate 22 fuses and I 0 relays.The Saab 900 models for the U.SA and Canada have a breakerless electronic ignition system. The ignition setting can be checked andset by means of an electronic instrument connected to special terminals in the electrical distribution box. The equipment has high accuracy and the ignition can be set very quickly.But scope is still availab le for using a stroboscope lamp.

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GEARBOX

The advantages and disadvantages of themanual gearbox versus the automatic transmission are the subject of much discussion.Without ende a voring to take sides in thediscussion. th e following facts can be stated:

The normal driver can achieve betteracce leration with an automatic transmissionthan with a manual gearbox (at a givenengine output). However. very experienceddrivers can accelerate faster by manualgear-changing. since they can utilize betterthe maximum output of the engine.

The top speed of a car with a manualgearbox is J - 4 higher .

Investigations have shown that the driversof cars with automatic transmission aremore relaxed. This is due primarily to thefollowing factors:

They have fewer manual operations tocarry out (they concentrate more on thesurrounding traffic)They have better control of the car (bothhands on the s t ~ r i n gwheel , simpleroperation when crawling in densetraffic. starting uphill. driving on a slippery road. etc .)They can never start the engine with agear engaged (the cause of many accidents and near-accidents on cars withmanual gearbox)

At a constant road speed. a car with auto

matic transmission has a fuel consumptionwhich is about 5 higher than that of a carwith a manual gearbox. However. in busycity traffic. the consumption is about thesame.

Owing to the absence of a clutch . the automatic transmission involves lower maintenance costs than the manual gearbox.

MANUAL GEARBOX

The manual gearbox is of sturdy design andhas four fully-synchromeshed forward speeds. The gearbox is separated from the enginecrankcase . but is integrated with the final driveand differential. to form a separate unit withits own lubrication system. The drive shaftshave double universal joints. the outer ofwhich are of the Rzeppa type . to providesmooth steering and an accurate feel in thesteering wheel. even on fast cornering. The inner and outer universal joints are both permanently lubricated. The power transmissionsystem has combined splash and circulationlubrication. The crown wheel of the finaldrive pumps oil through an oil way to the gearbox and primary drive . Other oil ways return

the oil back to the final drive. The gearcase isprovided with cooling fins.

The Saab 900 is equipped with a hydraulicallyactuated. single dry plate Borg Beck clutch.The primary drive consists of a duplex chaininstead of gears. The advantage is reducedwear and minimized chatter at idle . Since theclutch is fitted at the front of the engine. it ismore easily cooled. and this extends the usefullife of the friction linings . Service work on theclutch is also facilitated .

AUTOMATIC TRANSMISSION

The automatic transmission on the Saab is thewell-proven Borg-Warner type 35. It has beenspecially matched to the demands of the Saabca r . and is integrated with the engine.The torque converter. chain . gearbox anddifferential are integrated into one unit. andthe automatic control equipment of thetransmission is incorporated into the frontof the gearcase. where it is easily accessiblefrom below .

The torque converter is oil-filled and consistsof three components: The pump . the turbineand the stator. The pump impeller is connected to the engine crankshaft. whereas the turbine drives the input shaft of the automatictransmission. The stator is fitted on a freewheel coupling with a fixed hub. The oildelivered by the pump impeller causes theturbine to rotate. When the driving and driven

wheels rotate at different speeds. the statorguides the oi l back to the pump impeller insuch a direction that the torque of th e pumpimpeller increases. The torque amplificationmay vary from a maximum of about 2.3: Idown to I: I . and all amplification ceases whenthe turbine rotates at about 90 of the pumpimpeller speed.

Owing to the torque converter. the caraccelerates briskly and smoothly from lowspeeds. without the need for changing down.The Saab automatic transmission thus has alarge amount of over lap . which eliminatescontinual changing up and down when driving in city traffic. Gear-changing tqkes placeentirely automatically. since the pump. gover

no r . valves and servo pistons of the hydraulicsystem actuate the various units in the transmission to suit the road speed and enginespeed conditions. Overriding changing down- known as k ick -down- is available at speeds up to about 55 mph (85 km / h) by brisklydepressing the accelerator pedal to the limit s ofits travel.


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aab Turbo the car o the futureThere is certainly no other car in the world I can think of right now that isapable of carrying.five adults in comfort while match ing the performance, ridend handling andfuel economy balance of he Saab Turbo. It's in a class byself. . . the most exciting sports sedan in America . .

Motorsports Weekly, US.A.)

. . ranks among the best and most exciting automobiles we have ever tested.We were impressed with the Saab Turbo to the point that it will probably become

e standard by which all other cars are judged. Need we say more?A utosport, Canada )

Brilliant, exciting, thrilling. . The words.flowed unabated/ram our enthusiasc road test staff . . here is a car which brings a new dimension to motoring. Itoes ways beyond our expectations . .Wheels , Australia)

ft is difficult to put into words the charm andfascination of his remarkablear. As a combinatio n o.f performance, refinement, andfuel economy, it standsone, and the integrity qf ts engineering and the quality of ts.finish are secondnone. you were to concludefromthe above tha t this is just about the best mo

r car which is at present being made, anywhere, you wouldn't be far wrong.A utosport, Gt. Britain)

Directional stability isfautless, even at high speeds. Cross-winds are hardly noceable. The ca r has a slight amount qf understeer on cornering. load variaons, even when they are intentional, arebarely perceptible. The brake systemiscs all round) is entirely ade quate for the increased engine output.

A uto-Zeitung, Germany)

E UNIQUE

AAB TURBOCHARGED ENGINE

e turbocharging of automotive engines isthing new. and Saab-Scania has accumula

d a wealth of experience from the turboarging of truck and bus engines. But theab Turbo engine is unique by being therld s first to be matched to the wishes andeds of the everyday motorist.

rbo is the abbreviation for turbocharger. i.e.bine-driven compressor. In a turbochargedgine. the exhaust gases are routed through abine, which is thus induced to rotate at very

gh speed. The maximum speed is above0 000 re volutions per minute.

e turbine (A) drives a centrifugal comp resr B) which. when it has attained a sufiently high speed, pressurises th e intake aira few tenths of a bar. t is this pressure in

ease which is known as turbocharging (orpercharging). Turbocharging thus suppliesore combustion air to the cylinders than thegine would be capable of drawing naturally.ore fuel ca n there fore be injected and burn As a result. the engine delivers apprecia bly

ore energy for every piston stroke and thuss a higher output.

CREASED

OW SPEED PERFORMANCE

e turbocharging technique applied by Saabfers from that so far employed by someer car manufacturers. The Saab method ofbocharging starts to increase the perfor-

mance at low engine speeds. The engine delivers maximum torque at 3 000 rpm. This iswhat makes the Saab Turbo engine unique. Itis matched to suit everyday motoring insteadof the competition car driver's demand for extremely high top speeds.

The turbocharged fuel injection Sa ab engine

develops 135 hp I 00 kW) at 5000 rpm. Theperformance is comparable to that of appreciably larger en g in es - such as six-cylinder oreight-cylinder en g in es - although at an appreciably lower fuel consumption. Larger engines consume more fuel and the massivepower resources are of no particular benefit,most of the time . on the road. The performance of a smaller engine is more than adequate during 8 85 % of all motoring situations. In the Saab Turbo. the economy of thefour-cylinder engine is maintained and the penalty of high fuel consumption is incurredonly when the extra power is actually used.

INGENIOUS

CHARGING PRESSURE VALVEThe characteristic feature of the Saab Turboengine is the exceptionally small turbinewhich can easily be accelerated to boost thepower substantially, even at low engine speeds. The duty of the compressor is to pressurize the combustion air supplied to the engine.But the pressure must not be too high.

since it may otherwise cause self-ignition andmay damage the engine. A charging pressurevalve C ) - sometimes known as the wasteg a t e - continuously maintains the chargingpressure at the correct level. regardless of variations in the engine speed. This charging pressure valve is so special that Saab-Scani a hassubmitted patent applications for it. This ishow it works under various conditions:

ld/i11g speed or /ig/111hro11/eAt idling speed or light throttle. the intake airis drawn through the air cleaner to the air now

meter of the fuel injection system and then tothe compressor section of the turbocharger.The air then nows through the throttlehousing and intake manifold to the combustion chambers. The exhaust gases from the engine now through the turbine which willrotate without absorbing or delivering power.At idling speed or light throttle, the chargingpressure valve is closed and all of the exhaustgases now through the turbine.

Heavy acceleratio11orfi1/l1hro11/e

On heavy acceleration or at full throttle. thegas now through the turbine will increasesignificantly. This will also cause the turbineto rotate at a higher speed. and the compressorwill start supplying combustion air to the engine. In other words. the engine will be supplied with more air and fuel. and its output willincrease. If the accelerator pedal is depressedfurther , the charging pressure valve will openand will by-pass some of the exhaust gasesacross the turbine. since the pressure wouldotherwise exceed the maximum permissiblevalue.


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he Guldkuggen , (the Golden Cogwheel) is the.foremost an nual w rd inwedish business.for innovative thinking in engineering or commerce. The prize

winner is selected by jury and.for 1978 the head o fSaab-Scania's EngineDepartment was presented with this outstanding w rd for pioneering efforts inhe development q f he Saab turbo engine.for passenger cars .

VERSPEED AND HIGH PRESSURE

ROTECTION - DOUBLE SAFETY

the charging pressure at the intake manifoldhould nevertheless exceed the maximum perissible value. a pressure switch will automac a l l y - although temporarily - interrupte fuel supply to the engine. The car should

hen. when convenient. be driven lo a workhop for service. A pressure gauge on theashboard indicates at all times the variations

the charging pressure with the output of thengine .

n view of the high reserves o f power of theurbo engine . it would be easy to overspeed it.articularly in low gear. To prevent this . theurbo engine has been equipped with a safetyevice which limits the speed to a maximum

6000 rpm . When the engine speed has risen6000 rp m . a relay will interrupt electric cur

nt to the fuel pump until the engine speedas fallen back to an acceptable level.

he pictures show the arrangement of therbocharging system and the locations of the

arious components in a non catalyst.

I . Turbocharger2 Charging pressure valve3. Enrichment switch4. Deceleration solenoid5. Pressure switch

6 Control pressure valve7 Pressure controller8 Solenoid valve9 Fuel / air mixture meter

I 0 Speed limiter ignition pulse sensing fuel

pump relay)

TURBOCHARGING AND TUNING

ARE TWO DIFFERENT THINGS

The turbocharging of an engine in accordancewith the Saab method is not analogous totuning in the accepted sense. On the contrary.The turbocharged Saab Turbo engine deliversits maximum torque at a lower speed. and thecompression ratio is lower than that of thestandard engine.

The useful life of an engine is dependentprimarily on two types of w e r the speed-dependent wear and the temperature-dependent wear. The speed-dependent wear of the

Saab Turbo engine is probably lower than thatof the standard engine. This is due to the 6000rpm rev limiter and to the fact that the overallnumerical transmission ratio is I 0 lowerthan that of the standard transmission. and theengine speed is thus correspondingly lower ata given road speed. This higher ratio naturallyalso

reduces the fuel consumption. The movingparts of the engine - the crankshaft. connecting rods. main bearings and valve mechanism- are therefore subjected. in practice . to lesswear at a given road speed than those of theconventional fuel injection engine.

The temperature-dependent wear is no higher

in the turbocharged version of the engine thanin the conventional fuel injection engine. Theexhaust gas temperature is approximately thesame in both versions. although the exhaustgas now is appreciably higher in the turbocharged engine. This demands a better coolingcapacity and better heat dissipation at certainpoints. Components exposed to heat are therefore protected. modified or uprated to withstand the extra engine output with a comfortable margin. This applies. for instance. to thecooling systems for water and oil. to the intakeand exhaust valves . pistons. piston rings andthe exhaust system. The engine requires nospecial spark plugs . The turbocharged enginetherefore has the same good idling and lowspeed performance as the conventional fuelinjection engine.

The Turbo engine is also equipped with an ignition distributor with a double acting pressure capsule which retards the ignition by fivedegrees when the turbocharger comes intooperation. This reduces the risk o f self-ignition( knock ) at high speeds.


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Roadholding in theory nd practiceThe Saab was one of he best cars for winter conditions. ut the 900 has an

almost I 0 cm longer wheelbase and is even steadier.Expressen, Sweden)

WHY DOES A SKID OCCUR?

When a tire runs on the road surface. the

ubber at the contact surface at any instant cane regarded as a block resting on the road. Asoon as the tire is subjected to driving . brakingr lateral forces. frictional forces come intolay. F max is the maximum frictional forcehich the rubber block can withstand without

moving.

max = Nhere

= Coefficient of friction= Normal force (load on the wheel)

o the rubber block . the direction of the forceimmaterial - the relat ionship F = . N is

alid regardless of the direction of the force.f the forces acting on the tire should exceedhe maximum permissible frictional force. there will start to slide on the s u r f a c e - theheel will spin or skid sideways.

The various forces acting on the tire whilehe car is travelling can be illustrated graphially by a parallelogram of forces. The circlenscribing the parallelogram can be used toalculate the magnitude of the lateral forcehich the tire can withstand when subjected

o certain driving or braking forces - theadius of the circle represents a yardstick ofhe resultant force which the tire can withand. When the maximum braking or driving

apacity is utilized. one or several tires may benable to withstand any lateral forces whatv e r one or more tires may therefore starto skid sideways. so that the car is thrown offourse.

VERTAKING ON A SLUSHY ROAD

When the road behaviour of a car is discussed.he concepts of understeer. oversteer andeutral steering are often used. If a car takes aorner at high speed and the radius it describes

greater than that corresponding exactly tohe movement of the steering wheel . the car isaid to have understeer. Under the sameonditions. if the radius described by the car ismaller than that corresponding to the steering

wheel travel. the car is said to have oversteer.eutral steering describes the behavior of aar which lies between the two behaviorsescribed above.

n a car with rear wheel drive (which isormally characterised by understeerl, thebility of the rear wheels to withstand lateralorces is impaired when the car is accelerating.

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The rear wheels thus have a greater tendencyto run off course than the f ront wheel s - inother words. the normal understeer of the carmay instead become oversteer when the car isaccelerated hard. The car may therefore bedifficult to manoeuver on a slippery surface.such as when overtaking on a slushy road oracross a mound of snow between the lanesof a road. In the figure . .

D 1 and D are the driving forcesF 1 is the rolling resistance

F2 is the rolling resistance + the resistancepresented by a mound of slushy snow. forinstance.

Since F 2 is greater than F 1 a horizontal turning moment will be applied to the car. If therear wheels are simultaneously subjected tohigh driving f o r c e s - as is normal on overtak i n g a serious risk is involved due to thetires not being capable of withstanding the lateral forces caused by the horizontal turningmoment. The car will skid off course.

si


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uggage and stowage spacesIf there is a sedan with more usable interior space, more places to put things,

more room to carry things, more space to haul things, more ways to store thingswithout exposing them to prying eyes, we flat don t know o f t(Road Test about the Saab 99 Cambi Coupe, August 1977)

The Saab 900 has a hatchback body , and Saabwas one of the first car manufacturers tolaunch this very practical type of body in anup-to-date version. The hatchback was an unconventional model which combined the bestproperties of a conventional sedan, a coupeand a station wagon. without being burdenedwith any of their disadvantages. As compared

to an estate car . for instance, the load-carryingarea is of about the same size , although thebody styling is much more elegant. the soundlevel is lower, the rear window tends not tofoul , the fuel consumption is lower and spaceis available for concealing valuable luggage.

THREE VERSIONS

The load-carrying area can be convertedsimply and quickly to three different versions:

- 21.2 cu ft (600 litres) of luggage space,12.5 cu ft (350 litres) to SAE standards

5 seats . parcel shelf in position)23 cu ft (650 litres) of luggage space.15.4cu ft (435 litres) to SAE standards 5 seats ,parcel shelf removed)53 cu ft (I 500 litres) station wagon space2 seats)

A further 3.2 cu ft (90 litres) or I. I cu ft (30litres) to SAE of space is also available belowthe rear of the luggage compartment floor.

THE PARCEL SHELF

CAN BE RAISED OR REMOVED

The ordinary luggage compartment is 44. l inI 2 cm) long at floor level and accommodates12.5 cu ft 050 litres) by SAE s tandards- in

other words. about this volume of standardluggage units can be accommodated. The parcel shelf can be raised or removed altogether,and the car can then be loaded right up to theroof. The parcel s helf can be placed on thefloor. A plastic-covered metal wire net is available as an accessory and can be fitted bet weenthe back-seat backrest and the roof.

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CONVENIENT LOADING

The large rear door ensures convenient loading of bulky goods . The complete absence ofa sill allows even heavy luggage to be loaded

quickly and simply. The height of lift is nomore than 21 in (53 cm).

The space typical of a compact station wagoncan be obtained by folding down the back seatand the backrest. The conversion is quick andeasy. The load-carrying floor is flat and is covered with an edged carpet made of syntheticfiber. The spare wheel is located to the left andis easily accessible. even when the car is loaded. In the stat ion wagon mode the loadcarrying floor is 71. 7 in ( 182 cm) long andabout 89 .6 (215 cm) diagonally.

The rubber-covered bumper can be used as asupport and a ramp when loading heavyand long items. Since the door is hinged at theroof, the opening is substantial - the vertical

height is no less than 31.5 in (80 cm). Themaximum width of the door opening is 41 .7 inI 06 cm). During loading , the parcel shelf canbe locked in the raised position by means of aspring-loaded latch.

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IMPACT-ABSORBING.

INSULATING AND FIRE-RESISTANT

The wheel housings and side walls are linedwith molded panels made of0.4 in I 0 mm)thick plastic foam material with a surface covering of tough vinyl. The material is impact

absorbing. sound and heat insulating and fireresistant. t is resistant to oil and is easy to keepclean. The rear door is similarly lined. Thedoor is equipped with an inner handle. so thatit can be closed without getting your handsdirty. A well-protected lamp is switched onand off automatically as the rear door is opened and closed.

EXTRA SPACE

A 3 .2 cu ft (90 litres) compartment is providedbelow a panel at the extreme rear of the luggage compartment. The floor is covered with anylon carpet. The compartment provides apractical space for a spare fuel can . warningtriangle , tow rope. tools , jack . etc .

ILLUMINATED

GLOVE COMPARTMENT

The glove compartment can be locked bymeans of the ignition and door key. Whenopen , the glove compartment lid remains inthe horizontal position . t is provided with tworecesses on the inside, intended as holders forglasses or mugs, a practical feature when taking a break during a journey. The glove compartment is illuminated.

)INSTRUMENT PANEL RECESS

A practical recess intended for coins. cigarette

packets and other small items which maycome in handy during a journey is provided atthe top of the instrument panel.

The front doors are provided with roomypockets .

LARGE ASHTRAYS

The large ashtray is located at the bottom edgeof the instrument panel, with the cigarettelighter above it. Ashtrays are also fitted in botharmrests at the back seat.

FRONT AND REAR TOW LUGS

All Saab 900 models include provisio n forsimple fitting of a tow hitch. Tow lugs areprovided at the front and rear.


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Technical specificationsSaab 900 1979 year models

Dimensions and weightsOUTSIDE DIMENSIONS

Overall length including bumpers ........ 4764 mm 187.6 in)Wheelbase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .......... 2525 mm 99.4 in)Front overhang I 050 mm 41.3 in)Rear overhang . .. .. .............. . .. 1189 mm 46.8 in)Overall width . .. ........................ ............. . .. 1690 mm 66.5 in)Track, front. all except 3-door Turbo ... 1420 mm 55.9 in)Track, front. 3-door Turbo ....... .. ..... .......... 1430 mm 56.3 in)Track. rear. all except 3-door Turbo 1430 mm 56.3 in)Track, rear. 3-door Turbo .... ... .. ............ . . . .. 1440 mm 56. 7 in)Height at curb weight) ... ....................... . . ... 1420 mm 55.9 in)Ground clearance at curb weight ona nat surface) ........................................ .Clearance angle. front

INSIDE DIMENSIONS

Headroom between front seats and rooflining SAE H6 l ). cars without sun roof .Headroom on cars with sun roof.Headroom between back seat and rooflining SAE H63) for the outer passengers 2)Headroom for the centre passenger 3) .Width at shoulder height at the front

150 mm 5.9 in)18

955 mm 07 .6 in)934 mm 06.7 in)

956 mm 0 7 7 in)975 mm 08 .4 in)

SAE W3l. 3-door models ...................... . . . ... .. .. 1328 mm 52.3 in)Width on 5-door models. . . . . . . . . . . . . . . . . . . . . . . 1350 mm 53.2 in)Width at shoulder height at the rearSAE W4l. approx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Width at hip height at the frontSAE W5). 3-door models.

Width on 5-door models ................. .Width at hip height at the rearSAE W6), 3-door models ............ .. .

Width on 5-door modelsElbow room at the rear.

1355 mm 53.4 in)

.. 1233 mm 48 7 in)

.. 1343 mm 529 in)

.. 1296 mm 51.0 in)1357 mm 53.4 in)

3-door models ....................... . ......................... 1531 mm 60.3 in)Width on 5-door models ................................... 142 7 mm 56.2 in)Max. effective legroom at the front to theaccelerator pedal SAE L34) ............................. I 04 7 mm 41 .3 in)Effective legroom at the rear to the an k leoint centre SAE LS I) . 929 mm U6.6 in)

2) The specified dimension applies to G L models. The corresponding

dimension on the EMS and 3-door Turbo is 950 mm 07 .4 in) andon the GLE and 5-door Turbo. 945 mm 37 .2 in).

3) The specified dimension applies to the 3-door GL. Correspondingdimensions on other models: 970 mm 08.2 in) on the EMS and 3-door Turbo. and 962 mm 07 9 in) on the GLE and 5-door Turbo.

LUGGAGE COMPARTMENT SPACE

Length of luggage compartment noorSAE L203) . . ........... ........... ........... ........... .. . .. 1117 mm 44.0 in)

Length with the back seat folded down ........ 1821 mm 71.7 in)Total volume of the luggage compartment 600 dm 3 2 I .2 ft 3)Luggage compartment capacity SAE VI) 350 dm 3 12.4 ft 3)Capacity with the parcel shelf removed 435 dm 3 15.4 ft 3)Total load-carrying volume with back seat folded . 1500 dm 3 53 ft 3)Extra space below the luggage compartment noor 90 dm 3 3.2 ft 3)Load volume index SAE VJ). approx ....................................... 1550

Height of the rear door openi ng vertical) 795 mm 01.3 in)Height from the ground to the bottom edgeof the rear door opening. approx. ............... . 530 mm 20.9 in)Width of luggage compartment noorbetween wheel housings SAE W201) .............. . .. 991 mm09.0 in)Width of luggage compartment openingatnoorlevel SAEW203) ................................ . .. 9 0 7 m m 0 5 . 7 i n )Width at waist level SAE W204) ..... I062 mm 41.8 in)

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WEIGHTS

Curb weights3-door GLi3-door EMS5-door GLE3-door Turbo5-door Turbo

.. 2685 lb. 1220 kg)...... 27 30 lb 124 0 kg)

2775 lb 1260 kg)...... 2775 lb 126 0 kg)

2 8 8 5 I b I 3 I 0 kg)

Note: The specified curb weights are applicable to the lightest variants. Add about 44 lb) 20 kg) for sun roof or automatic transmission.The sun roof and automatic transmission together increase the weightby 77 - 88 l b ( 3 5 - 4 0 kg)

Gross vehicle weight rating .................................... 3830 lb. 1740 kg)Weight distribution, percentage of curb weightresting on the front wheels ........................ 5 7 . 7 - 6 0Recommended maximum weight of load inexpanded luggage compartment ..................... 480 lb. 220 kg)The total load-carrying capacity is always at least 950 lb 430 kg),

which corresponds to 5 persons each weighing 150 lb 70 kg)+ I 7 5 lb80 kg) of luggage . For every decrease in the number of passengers inthe back seat by I person. the load can be increa sed by 65 lb 30 kg).Highest permissible weight o f trailerwithout brakes ....................................... .Highest permissible load on the roof .

MotorALL VERSIONS

In-line . four-stroke. water-cooled gasoline engine.Overhead chain-driven camshaft.Number of cylinders 4Cylinder bore 90 mm 0 .54 in)Piston stroke 78 mm 0 .07 in)

I 000 lb. 450 kg). .... 220 lb. I 00 kg)

Displacement 1.985 dm 3 12 I cu in)Mean piston speedat5000rpm 13.0m/s 42 .7ft /sec)

The engine is mounted in the longtitudinal direction of the car. withthe clutch end facing forward and the cylinders inclined at 45 to theright. From the clutch. power is transmitted by means of a primarychain drive to the gearbox located below the engine. The cylinderblock is made of a special alloy cast iron. whereas the cylinder head isa light alloy casting. The crankshaft is forged and is supported by 5main bearings with replaceable bearing shells. The camshaft is a special casting and is also supported by 5 bearings.

The intake and exhaust ports in the cylinder head are arranged in across-now pattern. The pistons are made of light alloy.

The crankshaft drives an auxiliaries shaft which. in turn. drives the oil

pump , water pump, ignition distributor and. on carburet ter engines.also the fuel pump. Lubrication is by oil circulation under pressureand the lubrication system incorporates a full-now oil filter. Closedcircuit crankcase ventilation.Lubricating oil capacity.including filter 3.5 I 0 .7 U.S. qtslLubricating oil capacity.including filter and oil cooler 4.0 I 4.3 U.S. qts)


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F UE L INJEC T ION ENGI NES E XCLUDIN G THE T U R B O )

a ars for the U S A federal regio nE ng in e for all mo dels of t he 9 0 0 G L . EMS and GLECo m pression ra tio 9 . 2: IRa tin g SA E net (ap p ro xc o rre s p o nding to D I NPea k to rque . DINFu e l i njection sy s t e mRec o m m e n d e d octane numberIg niti o n t imingBrea ke rles s ign i t ion system E miss io n co ntrol e qu ipment

No coo le r for the en gine oil

85 kW (1 1 5 hp) at 5 5 0 0 rpm16 7 Nm ( 123 ft lbs.) at 3 5 0 0 rpmB o sch Cl Continuou s Injectio n )94 RO N Resea rch Octane Number )20 b e fo re TD C at 200 0 rpm

V ac uu m -c o n tr o l led decel era t ionv al v e. tw o -s t a g e EG R Exhaust GasR ec i rcu la t ion) p u l se -a ir in jec t io n .ti m in g a d v a n ce de lay va lve

b a rs for alifo rnia an d certain hig h altit ude areas in the U S AE n g ine for a ll Saab 900 mo d e l s with Calif ornia sp eci f ica t ion - exclth e T u rb o mo d e ls .Co m pr e ss ion r atio

Ra tin g SAE n e tPea k to rque . SAE netFue l inje ction system Fue lIg niti o n t imi ngBrea kerl ess ignition systemE miss io n cont ro l equipme nt

No co o le r for the engine o il

8 .7: I

81 k W l lOh p)at5500 rpm161 N m ll 9 f t . lbs .la t3500 rp mBosch Cl Le a d -free fue l 91 RON20 b e fo re TDC a t 2 0 0 0 rpm

Vacuum- contr olled d e celera t ionv a lve . La m b da System and cata lyst .

1 4 2

cl a r s f or the anad ian m arketBasic e ngine fo r E MS an d GL E m odels t o Ca nadaC ompression ra t io 9 .2 : IRat ing . D I N 8 7 kW ( 118 hp) at 550 0 rpmPe a k torque . DI N 16 7 Nm ( 123 ft lb s .) at 3 7 0 0 rpmTop speed . approx . E M S 17 6 k m / h . GL E 17 1 km / hAc c e lera t ion 0 1 0 0 k m / h.approx . EMS 12 2 s . G LE 13 .8 s

Bosch CI Continuou s In je c tion)uel in jec t ion sy stemRecomm e nded octane numb erPosi t ion of p is ton on fi r ing:

9 7 R O N (R e se a rc h Octane Number)

- Cars with manu al gearbox 20 b e fo re TD C at 200 0 rpm

- Cars with autom . t ra n sm is -si o n 23 b e fo re TDC at 200 0 rpmEx h a ust gas e mi s s i o n control e quipment :- Cars w ith manual gearbo x Vacuum -contr olled de c elerati o n

v a l v e . t i mi n g advance delay va lve - Cars wi t h autom . tran s m is -

s ion Va cuum -controlled deceler a t ionvalv e . t wo -s t a g e EGR E xhau s t Ga sR eci rcu la t ion)

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Engin eerin g Feature sSa a b 90 0 1979 m ode l range

Fo r int ernal use only

Saab 900 Engineering features 1979 [OCR]

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