Which statement best describes the effect of a longer collector on engine power range?

• A. It reduces fuel efficiency
• B. It has no measurable effect
• C. It reduces top-end power
• D. It improves low-to-mid-range power

Answer: (D)

Longer collector length tunes how exhaust pulses from multiple cylinders combine, which shapes how well the engine breathes at different speeds. When the collector is longer, the exhaust pressure waves take longer to travel and reflect back to the cylinders. That timing helps push exhaust out and pull fresh intake charge into the cylinder more effectively at lower to mid RPM, improving scavenging and therefore torque in that range. At higher RPM, the same length can create more back pressure and hinder flow, reducing top-end power. So the best description is that a longer collector improves low-to-mid-range power because it enhances scavenging at those speeds, with potential trade-offs at higher RPM.