Question 1

Boost pressure is generally measured in ________.

Accepted Answer

Boost pressure is typically measured in pounds per square inch (PSI) as it is a standard unit for measuring pressure in automotive and mechanical systems.

Question 2

Two types of superchargers include ________.

Accepted Answer

Roots-type and centrifugal are two types of superchargers used to increase the pressure or density of air supplied to an internal combustion engine, thereby increasing the engine's power output.

Question 3

Which valve is used on a factory supercharger to limit boost?

Accepted Answer

A bypass valve is used on a factory supercharger to limit boost by redirecting some of the air back to the intake side of the supercharger or to the atmosphere, preventing the supercharger from producing too much boost pressure.

Question 4

How are most superchargers lubricated?

Accepted Answer

The answer of How are most superchargers lubricated?
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Question 5

How are most turbochargers lubricated?

Accepted Answer

Turbochargers are typically lubricated by engine oil under pressure, which is supplied through lines that connect the turbocharger to the engine's lubrication system. This ensures the moving parts within the turbocharger are adequately lubricated to prevent excessive wear and overheating.

Question 6

Two technicians are discussing the term "turbo lag." Technician A says that it refers to the delay between when exhaust leaves the cylinder and when it contacts the turbine blades of the turbocharger. Technician B says the term refers to the delay in boost pressure that occurs when the throttle is first opened. Who is right?

Accepted Answer

Turbo lag refers to the delay in response that occurs from the moment the throttle is opened to when the turbocharger delivers significant boost pressure to the engine. It is not directly related to the time it takes for exhaust gases to reach the turbine blades, but rather the time it takes for the turbocharger to spool up and provide additional intake pressure.

Question 7

What is the purpose of an intercooler?

Accepted Answer

An intercooler is used to reduce the temperature of the air entering the engine after it has been compressed by the turbocharger, which increases the engine's efficiency and performance by allowing it to burn fuel more completely.

Question 8

Which type of relief valve used on a turbocharged engine is noisy?

Accepted Answer

Blow Off Valve (BOV) and Dump valve are essentially the same component, referred to by different names. They are designed to release excess pressure from the turbo system to the atmosphere, which creates a distinctive noise.

Question 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. Who is right?

Accepted Answer

Technician B is correct because a clogged PCV (Positive Crankcase Ventilation) system can cause increased pressure in the crankcase, leading to oil being pushed past seals and burned in the combustion chamber. A stuck open wastegate primarily affects turbocharger performance and boost levels, not oil burning.

Question 10

What service operations is most important on engines equipped with a turbocharger?

Accepted Answer

Regular oil changes are crucial for engines equipped with a turbocharger because the turbocharger relies on a constant supply of clean oil for lubrication and cooling. Dirty or degraded oil can lead to turbocharger failure.

Question 11

Technician A says that volumetric efficiency is a comparison of the actual volume of air-fuel mixture drawn into the engine to the theoretical minimum volume that can be drawn into the cylinder. Technician B says that a supercharger consumes some engine power as it forces a greater amount of air into the cylinders for more power. Who is right?

Accepted Answer

Volumetric efficiency is a comparison of the actual volume of air-fuel mixture drawn into the engine to the theoretical maximum volume, not minimum. Technician B is correct that a supercharger uses some engine power to increase air intake.

Question 12

All of these are advantages of supercharging an engine, EXCEPT ________.

Accepted Answer

Allows the engine to run on lower pressures is not an advantage of supercharging an engine. Supercharging increases the air-fuel charge density, which in turn increases the power output of the engine.

Question 13

Technician A says that a turbocharger uses the normally wasted heat energy of the exhaust to turn an impeller at high speed. Technician B says that there is only one type of supercharger, the roots-type. Who is right?

Accepted Answer

Technician A is correct because turbochargers do indeed use the energy from exhaust gases to spin a turbine, which then drives a compressor to force more air into the engine, increasing its power. Technician B is incorrect because there are several types of superchargers, including the Roots-type, centrifugal, and twin-screw, among others.

Question 14

Technician A says that a bypass valve is used to control the boost pressure on most factory installed superchargers. Technician B says that an intercooler is used on many turbocharged and some supercharged engines to reduce the temperature of air entering the engine for increased power. Who is right?

Accepted Answer

Technician A is correct because a bypass valve (also known as a blow-off valve) is indeed used in supercharged engines to control boost pressure by diverting excess air, preventing damage and ensuring the engine runs smoothly. Technician B is also correct because intercoolers are used in both turbocharged and supercharged engines to cool the air entering the engine, which increases its density for improved combustion and, consequently, more power.

Question 15

Technician A says that a wastegate is used on most turbocharger systems to limit and control boost pressures. Technician B says that a relief valve is also used to keep the speed of the turbine wheel from speeding up during engine deceleration. Who is right?

Accepted Answer

Technician A is correct because a wastegate is indeed used in turbocharger systems to control and limit the boost pressure by diverting some exhaust flow away from the turbine wheel, preventing it from spinning too fast and generating excessive boost. Technician B is incorrect because the primary function of a relief valve (or blow-off valve) in a turbocharged engine is to prevent compressor surge, not to control the turbine wheel speed during deceleration.

Question 16

The term "volumetric efficiency" refers to the ability of an engine to ________.

Accepted Answer

Volumetric efficiency is a measure of how effectively an engine can fill its cylinders with air. The more air (and fuel) an engine can draw into its combustion chamber, the more power it can produce.

Question 17

Which of these is defined as the mass or weight of a substance in a given amount of space?

Accepted Answer

Density is defined as the mass or weight of a substance in a given amount of space, typically expressed as mass per unit volume.

Question 18

When air is pumped into the cylinder, the combustion chamber receives an increase of air pressure known as ________ and is measured in pounds per square inch (psi), atmospheres (ATM), or bar.

Accepted Answer

Boost is the correct term for the increase in air pressure within the combustion chamber when air is pumped into the cylinder. This is a common term used in the context of turbocharged and supercharged engines, where the air pressure is artificially increased to improve engine performance. The pressure is indeed measured in pounds per square inch (psi), atmospheres (ATM), or bar.

Question 19

Many factory installed superchargers are equipped with a ________ that allows intake air to flow directly into the intake manifold bypassing the supercharger.

Accepted Answer

A bypass valve is used in supercharged engines to allow air to bypass the supercharger under certain conditions, such as low engine demand, to improve efficiency and reduce wear.

Question 20

Nitrous oxide injection adds ________ allowing the engine to burn more fuel.

Accepted Answer

Nitrous oxide injection adds oxygen to the engine, which allows it to burn more fuel by increasing the amount of oxygen available for combustion.

Quiz 25: Turbocharging and Supercharging