Turbo Seminar

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Boosting Your Knowledge of TURBO-
CHARGING
Randy Knuteson Analytical / Air Safety
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1905 Patent by Dr. Alfred J. Buchi
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Historical Perspective

• 1905 Sulzer Bros. designs first turbo

• 1910 G.E. begins manufacturing turbos
• 1915 First turbo diesel engine

• 1918 Dr. Sanford Moss altitude tests a 350 hp
  turbocharged engine.

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Historical Perspective

• 1920 New altitude record in a LePere
• Bi-Plane 33,113 feet!

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Historical Perspective

• 1921 John Macready's flight to 40,800' in an
  open cockpit Lusac 11, Lepere biplane.

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Turbo-Supercharged B-36
Six 28-Cylinder Engines
Without Turbos 90 Cylinders per Engine!
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ENGINE HORSEPOWER DEPENDS ON

• The amount of fuel and air an engine burns.

• The density of the charge, not the volume.

Soactual power is determined by the MASS of air
consumed.
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PRINCIPLES OF TURBOCHARGING
Sea-level air density 0.0765 lb. cu. ft.
At 10,000 ft. air density 0.0565 lb. cu. ft.
A Naturally-Aspirated Engine
100 hp _at_ sea-level
73.9 hp _at_ 10,000 ft.
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WHY TURBOCHARGE?

• Power diminishes with an increase in altitude.
• Gain more power and increase engine efficiency
  without enlarging the powerplant.
• Recapture the heat energy normally wasted out the
  exhaust.

GOAL Convert Exhaust Energy into Manifold
Pressure
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A TURBOCHARGER IS AN

• AIRPUMP powered by the unused heat energy
  normally wasted out the exhaust.

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Routing of exhaust and compressor discharge air
Filteredambient air inlet
Compressor outlet
Spent exhaust gases overboard
Exhaust gas inlet (T.I.T.) from the combustion
process
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1650 F
As high as 125,000 RPMs!
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TURBOCHARGING DEFINITIONS

• Turbocharging
• BOOSTED HP increase (31-45MAP)
• Turbo-Normalizing
• NORMALIZED Maintains sea-level performance
  (29.5 MAP) at altitude.

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TURBOCHARGING DEFINITIONS

• Upper Deck Pressure
• From compressor discharge to the throttle plate.
• Manifold Pressure
• From the throttle plate to the cylinder intake
  port.

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Sludge build-up in the wedge can decrease the
oil pressure feeding into the bearing and shaft
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TURBO COMPONENTSCENTER HOUSING home of

• BEARINGS
• For locating the turbine shaft
• SEALS (Piston Rings)
• Prevents high-pressure gases from entering the
  center housing and therefore the crankcase.
• To keep air and exhaust out of the oil.

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30-60 PSI
Piston rings keep air and exhaust pressures out
of the center housing
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TURBO COMPONENTSCOMPRESSOR STAGE (Cold Side)
Discharge Air
Volute shape converts velocity energy into
pressure energy
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Power increase
Exhaust volume increases
MAP increases
TURBO RUN-AWAY COULD EXCEED MAXIMUM ENGINE
OPERATING LIMITS!
Increased compressor discharge
Turbo begins to spin faster
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Decrease power
Decreased exhaust flow
MAP decreases
Compressor discharge decreases
Turbo slows down
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4 BASIC SYSTEM COMPONENTS

• Turbocharger
• Controller
• Wastegate
• Absolute Pressure Relief Valve (PRV)

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4 BASIC SYSTEM COMPONENTS
Aneroid Bellows
Upper Deck Pressure
Oil restrictor Valve
Engine Oil from Wastegaate Actuator
Oil Return to Engine
Throttle Controlled Cam
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4 BASIC COMPONENTS

• Wastegate (Exhaust Bypass Valve)

Oil Outlet to Controller
Butterfly Valve
Piston
Oil Inlet
Drain Port
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4 BASIC SYSTEM COMPONENTS

• Absolute Pressure Relief Valve (PRV)

Spring and Bellows Assy
Valve Face
Escape path for excess Upper Deck Air Pressure
Valve Seat
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Turbo output pressures must be regulated.
Without a control system, the turbocharged engine
would Be extremely unstable.
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Why Use an Intercooler?

• The compressor wheel spins faster at altitude
  producing a hotter charge to the cylinders.
• Decreasing adiabatic efficiency.

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TURBOCHARGERS ARE SENSITIVE TO

• Insufficient lubrication
• Foreign object damage
• Extreme temperatures

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INSUFFICIENT LUBRICATION

• RESULTS IN
• Bearing damage that causes an increase in the
  orbital motion of the turbine shaft.
• Turbine and compressor wheels begin to contact
  their respective housings.

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CONTAMINATED LUBRICATION RESULTS IN

• Damage to bearing(s)
• Collateral damage to turbine and compressor
  housings
• Full floating bearings require 30 PSI minimum at
  inlet (3 GPM)

• Engine Oil should be changed every 25-35 hours
  in a turbocharged engine.

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Lubricating Oil Recommendations

• Lycoming SI 1014M All turbocharged engines
  must be broken-in and operated with ashless
  dispersant oil only.
• TCM M87-12 Rev 1 Straight Mineral Oil
  (MIL-L-6082) may be used not to exceed 25 hours
  or 6 months of operation.

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VERIFY TURBO CONDITION

• Does the shaft spin freely?

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VERIFY TURBO CONDITION

• Wheels should not contact housing.

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VERIFY TURBO CONDITION
Use a light source to carefully examine the
condition of the leading edges of the Turbine
Wheel blades.
Check inducer blades for damage
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FOREIGN OBJECT DAMAGE

• Bolts, valves, and rocks will break pieces from
  the blades or machine them down.
• Abrasive matter (sand, dirt) will wear away the
  underside of the blades.
• Soft material (shop rags) will bend the
  compressor blades backwards.

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Avoiding Turbo Oil Leaks

• Drain ports must point down. (not more than 35
  degrees from vertical centerline)
• Drain line should slope entire length (no sink
  traps).
• Check hoses for internal de-lamination.

• No sludge at outlet From coking of bearing
  housing.

• Restriction or faulty check valve(s)

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TROUBLESHOOTING LOW/FLUCTUATING MAP

• Restriction in Duct Between Air Cleaner and
  Intake Manifold.
• Restriction in Engine Exhaust /Intake Manifold
• PRV Opens Prematurely (At Too Low a Pressure)

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TROUBLESHOOTING LOW/FLUCTUATING MAP
Leaking Cover Gasket

• T/C Output Low/Sluggish
• Engine Oil Pressure Low
• Controller/Wastgate Dirty or Sticking
• Controller Cover Gasket Leak

No Split-Lock Washers
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CONTROLLER MALFUNCTIONS

• Dirt / Debris in Poppet Valve
• Worn Poppet Seat Assembly
• Case / Gasket Leakage

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Wastegate Malfunctions

• Sticking / Frozen Butterfly valve

Caused by
Lead and E.G. deposits build-up on pivot bushings
Cure
Mouse Milk
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Testing the Wastegate Assy.
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How NOT to Check the Condition of the Pressure
Relief Valve
WARNING Never advance the throttle boosting
manifold pressure beyond red-line to determine if
the absolute pressure relief valve is
functioning. This is an emergency controller.
DONT TEST THE ABSOLUTE PRESSURE RELIEF VALVE ON
THE ENGINE!
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Overspeed/Overshoot/Overboost

• Overspeed

• Operating an engine above its rated speed or RPM.

• Overshoot

• Automatic controls cant respond quickly enough
  to the inertia of the turbocharger speed as it
  increases when the throttle is rapidly advanced.

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Overspeed/Overshoot/Overboost

• Overshoot

• Lycoming says

If overshoot does not exceed 2 inches and 3
seconds duration, it may be disregarded.
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Overspeed/Overshoot/Overboost

• Overspeed
• Overshoot

• Overboost

• Occurs when the manifold pressure exceeds the
  limits at which the engine was tested and FAA
  certified.

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OVERBOOST CAUSED BY

• Rapid throttle movement
• Exhaust By-Pass Valve fails to open.
• Sticking Wastegate
• Air in the oil feed to the controller
• PRV (pop-off valve) fails to open at
  predetermined crack point.

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UNACCEPTABLE OVERBOOST

• TCM SB67-12
• OVERSHOOT / OVERBOOST
• 3-6 INCHES Check System, Adjust or Replace
  Malfunctioning Components.

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UNACCEPTABLE OVERBOOST

• LYCOMING MSB-369J

• Not exceeding 5 inches Hg. or 10 seconds
  Normal 50 hour inspection required.

• Not exceeding 10 inches Hg. Complete engine
  disassembly and inspection.

• Over 10 inches Hg. Complete engine Overhaul
  and crankshaft replacement.

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ACCEPTABLE OVERBOOST

• LYCOMING MSB-369J

• Momentary - not exceeding 3 inches Hg. for 5
  seconds

Log Book entry required.

• Maximum manifold pressure reached.
• Duration of overboost
• Cylinder head temperature
• Ambient air temperature
• Pressure altitude

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ACCEPTABLE OVERBOOST

• LYCOMING MSB-369J

• Visual inspection of compressor and turbine
  wheels
• Manually check for excessive movement of turbine
  shaft in the journal bearings.

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CHECKING BEARING CLEARANCES
Radial Bearing Check
0.003-0.007
0.004-0.009
Axial End Play Bearing Check
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Maintenance of Turbo System

• Preflight Visual Inspection
• Check for security of turbo mountings and
  connections.
• Inspect for evidence of oil leakage, air leakage,
  or exhaust leakage.

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Maintenance of Turbo System

• 50 and 100 hour inspections

• Inspect the hoses and tubing of the air intake
  system.
• Check for leakage due to cracks, damaged gaskets,
  loose clamps or connections.
• Restrictions due to kinks, collapsed hoses, or
  dented tubing.
• Inspect for exhaust leakage.

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Maintenance of Turbo System

• 50 and 100 hour inspections

• Inspect the torque on all V-band clamps

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Maintenance of Turbo System

• 50 and 100 hour inspections

• Check oil feed and return lines.
• Unusual noises or vibration.
• Observe the engine exhaust.
• FOD damage to wheels or evidence of contact with
  housings.

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Turbo Cool Downs

• Allow for a two to four minute cool-down period.
• CHT drop 50 degrees from last power reduction
• EGTs 500 degree drop from Cruise Temps.

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