Car Tuning Forced Induction Systems 2

Question 1

What is 'boost creep' in a turbocharged engine?

Accepted Answer

Boost pressure rising uncontrollably beyond the target level

Answer

Boost creep occurs when exhaust flow exceeds the wastegate's ability to bypass it, causing boost to rise beyond the set target.

Question 2

Which material is most commonly used for high-performance intercooler cores due to its thermal conductivity and weight?

Accepted Answer

Aluminum

Answer

Aluminum offers an excellent balance of thermal conductivity, light weight, and ease of fabrication for intercooler cores.

Question 3

What does a 'twin-scroll' turbocharger improve compared to a single-scroll design?

Accepted Answer

Spool response and reduced turbo lag by separating exhaust pulses

Answer

Twin-scroll turbos separate exhaust pulses from paired cylinders, delivering more energy to the turbine wheel and improving spool-up response.

Question 4

When upgrading to a larger turbocharger, why might low-end torque decrease?

Accepted Answer

A larger turbine wheel takes more exhaust energy to spool up, increasing lag

Answer

A larger turbo's greater rotating mass and larger turbine wheel requires more exhaust gas energy before it reaches boost threshold, increasing lag.

Question 5

What is the function of a blowoff valve (BOV) in a turbocharged system?

Accepted Answer

Vents pressurized intake air when the throttle closes to prevent compressor surge

Answer

The BOV releases pressurized air trapped between the turbo and closed throttle body, preventing compressor surge and protecting the turbo.

Car Tuning Practice Test