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Engine Maintenance. Chapter 1 What Makes the Boat Go. Objectives for the Student. Have a good grasp of the components of the modern marine propulsion system Have an understanding of the principles of the modern marine engine, both two stroke and four stroke - PowerPoint PPT Presentation
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Engine MaintenanceEngine Maintenance
Chapter 1Chapter 1
What Makes the Boat GoWhat Makes the Boat Go
22
Objectives for the StudentObjectives for the Student
1.Have a good grasp of the components of the modern marine propulsion system
2.Have an understanding of the principles of the modern marine engine, both two stroke and four stroke
3.Have an understanding of the general troubleshooting methodologies that can be used and repair work that needs to be done
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The Marine EngineThe Marine Engine
Needed for combustion:Needed for combustion: fuelfuel air (oxygen)air (oxygen) ignition sourceignition source
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The Marine EngineThe Marine Engine
A compressed fuel/air mixture is ignitedA compressed fuel/air mixture is ignited
Burning mixture increases in temperature and Burning mixture increases in temperature and pressurepressure
Expansion of gas is converted to linear piston Expansion of gas is converted to linear piston motionmotion
Crank converts linear motion to rotary motionCrank converts linear motion to rotary motion
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The Marine EngineThe Marine Engine
IntakeIntake fuel/air enters fuel/air enters
the the combustion combustion chamberchamber
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The Marine EngineThe Marine Engine
CompressionCompression mixture is mixture is
compressed compressed within the within the cylindercylinder
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The Marine EngineThe Marine Engine
Power Power compressed compressed
charge is charge is ignited to move ignited to move the piston the piston downwarddownward
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The Marine EngineThe Marine Engine
ExhaustExhaust spent gases spent gases
are expelledare expelled
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The Diesel EngineThe Diesel Engine
IntakeIntake air enters the air enters the
combustion combustion chamberchamber
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The Diesel EngineThe Diesel Engine
CompressionCompression air is air is
compressed compressed to high to high temperaturetemperature
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The Diesel EngineThe Diesel Engine
PowerPower fuel is fuel is
injected and injected and autoignitesautoignites
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The Diesel EngineThe Diesel Engine
ExhaustExhaust the spent the spent
gases are gases are expelledexpelled
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DisplacementDisplacement
Cylinder DisplacementCylinder Displacement The total volume of air that can be moved in The total volume of air that can be moved in
one engine cycle for one cylinderone engine cycle for one cylinder BoreBore
Diameter of the cylinderDiameter of the cylinder
StrokeStroke Total piston travel from Total piston travel from
TDC to BDCTDC to BDC
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DisplacementDisplacement
Volume of a Right Circular CylinderVolume of a Right Circular Cylinder
• V = r2 h
• where
• V = volume
• = 3.1416
• r = radius (1/2 diameter) of cylinder
• h = height of the cylinder (stroke)
r
h
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DisplacementDisplacement
Engine DisplacementEngine Displacement The total volume of one cylinder’s The total volume of one cylinder’s
displacement, times the number of cylindersdisplacement, times the number of cylinders
• Displacement = n V = n r2 h
• where
• n = number of cylinders
•V = volume of one cylinder
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DisplacementDisplacement
Example: Chevrolet 350 V-8Example: Chevrolet 350 V-8 Bore = 4.00 inches (10.16 cm)Bore = 4.00 inches (10.16 cm) Stroke = 3.48 inches (8.84 cm)Stroke = 3.48 inches (8.84 cm)
Displacement = n V = n Displacement = n V = n rr22 h h
Displacement = 8 x 3.1416 Displacement = 8 x 3.1416 x (2.00 inches)x (2.00 inches)22 x 3.48 x 3.48 inchesinches
Displacement = 350 Displacement = 350 inchesinches33 or 350 cubic inches or 350 cubic inches or 350 cubic inches or 350 cubic inches displacement or 350 CIDdisplacement or 350 CID
Displacement = n V = n Displacement = n V = n rr22 h h
Displacement = 8 x 3.1416 Displacement = 8 x 3.1416 x (5.08 cm)x (5.08 cm)22 x 8.84 cm x 8.84 cm
Displacement = 5735 cc or Displacement = 5735 cc or 5.7 liters5.7 liters
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Size MattersSize Matters
Engines of Greater Displacement Engines of Greater Displacement Generally Deliver More HorsepowerGenerally Deliver More Horsepower More fuel/air consumed per strokeMore fuel/air consumed per stroke More heat releasedMore heat released More power producedMore power produced
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Engine CompressionEngine Compression
Compression RatioCompression Ratio The cylinder’s total volume at BDC, divided by The cylinder’s total volume at BDC, divided by
volume at TDCvolume at TDC
• Compression Ratio = V / v
• where
• V = volume at BDC• BDC = bottom dead center
• v = volume at TDC
• TDC = top dead center
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Engine CompressionEngine Compression Compression Ratio = V / vCompression Ratio = V / v
V = 8.8496 cubic inches (145 cc)V = 8.8496 cubic inches (145 cc) v = 1.0411 cubic inches (17 cc)v = 1.0411 cubic inches (17 cc)
V / v = 8.8496 / 1.0411 = 8.5:1V / v = 8.8496 / 1.0411 = 8.5:1 V / v = 145 / 17 = 8.5:1V / v = 145 / 17 = 8.5:1
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Horsepower and TorqueHorsepower and Torque
HorsepowerHorsepower measure of workmeasure of work 1 hp = 745 watts1 hp = 745 watts
TorqueTorque measure of rotational forcemeasure of rotational force
pounds-foot (lb-ft)pounds-foot (lb-ft) Newton-meter (Nm)Newton-meter (Nm)
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The Marine Drive SystemThe Marine Drive System
Three Basic Types of Marine Drives:Three Basic Types of Marine Drives: OutboardOutboard InboardInboard Stern Drive, also known as Stern Drive, also known as
Inboard/Outboard or I/O driveInboard/Outboard or I/O drive
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The Marine Drive SystemThe Marine Drive SystemOutboard SystemsOutboard Systems
Power Head
Intermediate Housing
Lower Unit
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The Marine Drive SystemThe Marine Drive SystemInboard SystemsInboard Systems
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The Marine Drive SystemThe Marine Drive SystemStern Drive (I/O) SystemsStern Drive (I/O) Systems
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Thrust UnitsThrust Units PropellerPropeller
2-4 blade (inboards)2-4 blade (inboards) 3-6 blades (outboards)3-6 blades (outboards)
PitchPitch measure of advance (one measure of advance (one
rotation through a solid rotation through a solid object)object)
DiameterDiameter diameter of a circle that diameter of a circle that
describes the blade tipsdescribes the blade tips
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Thrust UnitsThrust Units
Water JetWater Jet Internal impellerInternal impeller Good for shallow water operationGood for shallow water operation Directs thrust using steerable Directs thrust using steerable
nozzle and reverse gatenozzle and reverse gate
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General Troubleshooting General Troubleshooting MethodologyMethodology
Check the ObviousCheck the Obvious Check the EasyCheck the Easy Check SystematicallyCheck Systematically Make No Erratic AdjustmentsMake No Erratic Adjustments
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Remember…Remember…
You should be able to You should be able to identify problems and identify problems and explain them to a mechanicexplain them to a mechanic