Car Tuning Forced Induction Systems 5

Question 1

What does 'compressor map' data help a tuner determine when selecting a turbocharger?

Accepted Answer

Whether the turbo will operate in an efficient range for the target airflow and boost pressure

Answer

A compressor map plots airflow versus pressure ratio with efficiency islands, allowing tuners to verify the turbo will operate at high efficiency for a given power target.

Question 2

What is the primary function of a check valve (one-way valve) in a boost reference line for an external wastegate?

Accepted Answer

Allows boost pressure to flow in only one direction to control the wastegate solenoid

Answer

A check valve in a boost reference line ensures pressure signals travel in only one direction, preventing vacuum or reverse-flow conditions from interfering with wastegate control.

Question 3

Why do many turbocharged engines require head studs rather than head bolts when run at high boost levels?

Accepted Answer

Head studs clamp the head more evenly and maintain clamping force better under high cylinder pressures and thermal cycling

Answer

Head studs thread into the block and clamp with a nut, providing more uniform clamping load and superior resistance to the high cylinder pressures and thermal expansion cycles of forced induction.

Question 4

What is 'shaft play' in a turbocharger and what does excessive shaft play indicate?

Accepted Answer

Movement of the turbo shaft in radial or axial directions indicating bearing wear

Answer

Shaft play is the physical movement of the turbocharger shaft within its bearings; excessive play indicates bearing wear and can lead to compressor or turbine wheel contact with the housing.

Question 5

What is the purpose of a 'boost controller' (manual or electronic) in a turbocharged system?

Accepted Answer

Regulates or raises boost pressure by managing wastegate actuator duty cycle or bleed rate

Answer

A boost controller manipulates the pressure signal to the wastegate actuator, keeping the wastegate closed longer to allow boost to rise above the actuator's spring-set base pressure.

Car Tuning Practice Test

Car Tuning Practice Test

Car Tuning Forced Induction Systems 5