2. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 OBJECTIVES After studying Chapter 7, the reader should be able to: 1.Prepare for ASE Engine Performance (A8) certification test content area “C” (Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair). 2.Explain the difference between a turbocharger and a supercharger. 3.Describe how the boost levels are controlled. 4.Discuss maintenance procedures for turbochargers and superchargers.

3. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 AIRFLOW REQUIREMENTS Engineers calculate engine airflow requirements using these three factors: –Engine displacement –Engine revolutions per minute (RPM) –Volumetric efficiency

4. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 AIRFLOW REQUIREMENTS Volumetric Efficiency Volumetric efficiency is a comparison of the actual volume of air–fuel mixture drawn into an engine to the theoretical maximum volume that could be drawn in. Volumetric efficiency is expressed as a percentage, and changes with engine speed. FIGURE 7-1 A supercharger on a Ford V-8.

5. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 AIRFLOW REQUIREMENTS Volumetric Efficiency FIGURE 7-2 A turbocharger on a Toyota engine.

6. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 AIRFLOW REQUIREMENTS Engine Compression Higher compression increases the thermal efficiency of the engine because it raises compression temperatures, resulting in hotter, more complete combustion. –However, a higher compression can cause an increase in NO X emissions and would require the use of high-octane gasoline with effective antiknock additives.

7. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUPERCHARGING PRINCIPLES The amount of force an air– fuel charge produces when it is ignited is largely a function of the charge density. Density is the mass of a substance in a given amount of space. FIGURE 7-3 The more air and fuel that can be packed in a cylinder, the greater the density of the air–fuel charge.

8. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUPERCHARGING PRINCIPLES FIGURE 7-4 Atmospheric pressure decreases with increases in altitude.

9. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUPERCHARGERS A supercharger is an engine-driven air pump that supplies more than the normal amount of air into the intake manifold and boosts engine torque and power. A supercharger provides an instantaneous increase in power without the delay or lag often associated with turbochargers. –However, a supercharger, because it is driven by the engine, does require horsepower to operate and is not as efficient as a turbocharger.

10. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUPERCHARGERS Roots-type supercharger. Centrifugal supercharger. FIGURE 7-5 A roots-type supercharger uses two lobes to force the air around the outside of the housing and forces it into the intake manifold.

11. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUPERCHARGERS Supercharger Boost Control Many factory-installed superchargers are equipped with a bypass valve that allows intake air to flow directly into the intake manifold bypassing the supercharger. The computer controls the bypass valve actuator. FIGURE 7-6 The bypass actuator opens the bypass valve to control boost pressure.

12. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUPERCHARGERS Supercharger Service Superchargers are usually lubricated with synthetic engine oil inside the unit. This oil level should be checked and replaced as specified by the vehicle or supercharger manufacturer. The drive belt should also be inspected and replaced as necessary.

13. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 TURBOCHARGERS By connecting a centrifugal supercharger to a turbine drive wheel and installing it in the exhaust path, the lost engine horsepower is regained to perform other work and the combustion heat energy lost in the engine exhaust (as much as 40% to 50%) can be harnessed to do useful work. This is the concept of a turbocharger. FIGURE 7-7 A turbocharger uses some of the heat energy that would normally be wasted.

14. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 TURBOCHARGERS FIGURE 7-8 A turbine wheel is turned by the expanding exhaust gases.

15. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 TURBOCHARGERS Turbocharger Design and Operation A turbocharger consists of two chambers connected by a center housing. The two chambers contain a turbine wheel and a compressor wheel connected by a shaft which passes through the center housing. FIGURE 7-9 The exhaust drives the turbine wheel on the left, which is connected to the impeller wheel on the right through a shaft. The bushings that support the shaft are lubricated with engine oil under pressure.

16. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 TURBOCHARGERS Turbocharger Size and Response Time Turbocharger response time is directly related to the size of the turbine and compressor wheels. Small wheels accelerate rapidly; large wheels accelerate slowly. While small wheels would seem to have an advantage over larger ones, they may not have enough airflow capacity for an engine. To minimize turbo lag, the intake and exhaust breathing capacities of an engine must be matched to the exhaust and intake airflow capabilities of the turbocharger.

17. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 BOOST CONTROL Both supercharged and turbocharged systems are designed to provide a pressure greater than atmospheric pressure in the intake manifold. This increased pressure forces additional amounts of air into the combustion chamber over what would normally be forced in by atmospheric pressure. This increased charge increases engine power. The amount of “boost” (or pressure in the intake manifold) is measured in pounds per square inch (PSI), in inches of mercury (in. Hg), in bars, or in atmospheres.

18. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 BOOST CONTROL FIGURE 7-10 The unit on top of this Subaru that looks like a radiator is the intercooler, which cools the air after it has been compressed by the turbocharger.

19. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 BOOST CONTROL Wastegate A turbocharger uses exhaust gases to increase boost, which causes the engine to make more exhaust gases, which in turn increases the boost from the turbocharger. To prevent overboost and severe engine damage, most turbocharger systems use a wastegate. A wastegate is a valve similar to a door that can open and close. The wastegate is a bypass valve at the exhaust inlet to the turbine. It allows all of the exhaust into the turbine, or it can route part of the exhaust past the turbine to the exhaust system.

20. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 BOOST CONTROL Wastegate FIGURE 7-11 A wastegate is used on the first- generation Duramax diesel to control maximum boost pressure.

21. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 BOOST CONTROL Relief Valves A relief valve vents pressurized air from the connecting pipe between the outlet of the turbocharger and the throttle whenever the throttle is closed during boost, such as during shifts. There are two basic types of relief valves: –Compressor bypass valve or CBV. –Blow-off valve or BOV.

22. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 BOOST CONTROL Relief Valves FIGURE 7-12 A blow-off valve is used in some turbocharged systems to relieve boost pressure during deceleration.

23. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 IF ONE IS GOOD, TWO ARE BETTER FIGURE 7-13 A dual turbocharger system installed on a small-block Chevrolet V-8 engine.

24. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 TURBOCHARGER FAILURES When turbochargers fail to function correctly, a drop in power is noticed. To restore proper operation, the turbocharger must be rebuilt, repaired, or replaced. It is not possible to simply remove the turbocharger, seal any openings, and still maintain decent driveability.

25. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUMMARY 1.Volumetric efficiency is a comparison of the actual volume of air–fuel mixture drawn into the engine to the theoretical maximum volume that can be drawn into the cylinder. 2.A supercharger operates from the engine by a drive belt and, while it does consume some engine power, it forces a greater amount of air into the cylinders for even more power. 3.A turbocharger uses the normally wasted heat energy of the exhaust to turn an impeller at high speed. The impeller is linked to a turbine wheel on the same shaft and is used to force air into the engine.

26. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 SUMMARY 4.There are two types of superchargers: roots-type and centrifugal. 5.A bypass valve is used to control the boost pressure on most factory-installed superchargers. 6.An intercooler is used on many turbocharged and some supercharged engines to reduce the temperature of air entering the engine for increased power. 7.A wastegate is used on most turbocharger systems to limit and control boost pressures, as well as a relief valve, to keep the speed of the turbine wheel from slowing down during engine deceleration.

27. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 REVIEW QUESTIONS 1.What are the reasons why supercharging increases engine power? 2.How does the bypass valve work on a supercharged engine? 3.What are the advantages and disadvantages of supercharging? 4.What are the advantages and disadvantages of turbocharging? 5.What turbocharger control valves are needed for proper engine operation?

28. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 1.Boost pressure is generally measured in _____. a)in. Hg b)PSI c)in. H 2 O d)in. lb

29. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 1.Boost pressure is generally measured in _____. a)in. Hg b)PSI c)in. H 2 O d)in. lb

30. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 2.Two types of superchargers are _____. a)Rotary and reciprocating b)Roots-type and centrifugal c)Double and single acting d)Turbine and piston

31. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 2.Two types of superchargers are _____. a)Rotary and reciprocating b)Roots-type and centrifugal c)Double and single acting d)Turbine and piston

32. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 3.Which valve is used on a factory supercharger to limit boost? a)A bypass valve b)A wastegate c)A blow-off valve d)An air valve

33. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 3.Which valve is used on a factory supercharger to limit boost? a)A bypass valve b)A wastegate c)A blow-off valve d)An air valve

34. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 4.How are most superchargers lubricated? a)By engine oil under pressure through lines from the engine b)By an internal oil reservoir c)By greased bearings d)No lubrication is needed because the incoming air cools the supercharger

35. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 4.How are most superchargers lubricated? a)By engine oil under pressure through lines from the engine b)By an internal oil reservoir c)By greased bearings d)No lubrication is needed because the incoming air cools the supercharger

36. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 5.How are most turbochargers lubricated? a)By engine oil under pressure through lines from the engine b)By an internal oil reservoir c)By greased bearings d)No lubrication is needed because the incoming air cools the supercharger

37. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 5.How are most turbochargers lubricated? a)By engine oil under pressure through lines from the engine b)By an internal oil reservoir c)By greased bearings d)No lubrication is needed because the incoming air cools the supercharger

38. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 6.Two technicians are discussing the term “turbo lag.” Technician A says that it refers to the delay between when the exhaust leaves the cylinder and when it contacts the turbine blades of the turbocharger. Technician B says that it refers to the delay in boost pressure that occurs when the throttle is first opened. Which technician is correct? a)Technician A only b)Technician B only c)Both Technicians A and B d)Neither Technician A nor B

39. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 6.Two technicians are discussing the term “turbo lag.” Technician A says that it refers to the delay between when the exhaust leaves the cylinder and when it contacts the turbine blades of the turbocharger. Technician B says that it refers to the delay in boost pressure that occurs when the throttle is first opened. Which technician is correct? a)Technician A only b)Technician B only c)Both Technicians A and B d)Neither Technician A nor B

40. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 7.What is the purpose of an intercooler? a)To reduce the temperature of the air entering the engine b)To cool the turbocharger c)To cool the engine oil on a turbocharged engine d)To cool the exhaust before it enters the turbocharger

41. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 7.What is the purpose of an intercooler? a)To reduce the temperature of the air entering the engine b)To cool the turbocharger c)To cool the engine oil on a turbocharged engine d)To cool the exhaust before it enters the turbocharger

42. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 8.Which type of relief valve used on a turbocharged engine is noisy? a)A bypass valve b)A BOV c)A dump valve d)Both b and c

43. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 8.Which type of relief valve used on a turbocharged engine is noisy? a)A bypass valve b)A BOV c)A dump valve d)Both b and c

44. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 9.Technician A says that a stuck-open wastegate can cause the engine to burn oil. Technician B says that a clogged PCV system can cause the engine to burn oil. Which technician is correct? a)Technician A only b)Technician B only c)Both Technicians A and B d)Neither Technician A nor B

45. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 9.Technician A says that a stuck-open wastegate can cause the engine to burn oil. Technician B says that a clogged PCV system can cause the engine to burn oil. Which technician is correct? a)Technician A only b)Technician B only c)Both Technicians A and B d)Neither Technician A nor B

46. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 10.What service operation is most important on engines equipped with a turbocharger? a)Replacing the air filter regularly b)Replacing the fuel filter regularly c)Regular oil changes d)Regular exhaust system maintenance

47. Automotive Fuel and Emissions Control Systems, 2/e By James D. Halderman and Jim Linder © 2009 Pearson Higher Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458 CHAPTER QUIZ 10.What service operation is most important on engines equipped with a turbocharger? a)Replacing the air filter regularly b)Replacing the fuel filter regularly c)Regular oil changes d)Regular exhaust system maintenance