Twin turbocharger system uses two identical sized turbos matched with 1/2 of the engine's need. Technician B says that compound turbochargers use turbochargers that are the identical size. Which technician is correct?

Twin turbocharger system uses two identical sized turbos matched with 1/2 of the engine's need. Technician B says that compound turbochargers use turbochargers that are the identical size. Which technician is correct?

• A. Tech B
• B. Tech A
• C. Both
• D. Neither

Answer: (B)

Two different turbo layouts are at play here: parallel twin and sequential (compound). In a parallel twin setup, two identical turbos work together to meet the engine’s air demand, with each handling roughly half the load. Matching sizes helps balance boost and response, giving quicker spool and smoother delivery across the mid-range. In a sequential or compound system, the two turbines are arranged in series and are typically different in size: a small turbine spools quickly to start boosting, and a larger one follows to reach higher boost at higher RPM. They aren’t identical because the goal is to stack boost rather than simply share the load. So, the claim that twin-turbo systems use two identical sized turbos is correct. The claim that compound turbochargers use identical-sized turbos isn’t standard for compound setups, which is why that statement is not correct.

Two different turbo layouts are at play here: parallel twin and sequential (compound). In a parallel twin setup, two identical turbos work together to meet the engine’s air demand, with each handling roughly half the load. Matching sizes helps balance boost and response, giving quicker spool and smoother delivery across the mid-range. In a sequential or compound system, the two turbines are arranged in series and are typically different in size: a small turbine spools quickly to start boosting, and a larger one follows to reach higher boost at higher RPM. They aren’t identical because the goal is to stack boost rather than simply share the load.

So, the claim that twin-turbo systems use two identical sized turbos is correct. The claim that compound turbochargers use identical-sized turbos isn’t standard for compound setups, which is why that statement is not correct.