The proper engine break-in procedure must be performed at which speeds?

The proper engine break-in procedure must be performed at which speeds?

• A. 60 KM/H accelerating to 100 KM/H
• B. 40 KM/H accelerating to 70 KM/H
• C. 50 KM/H accelerating to 80 KM/H
• D. 20 KM/H accelerating to 40 KM/H

Answer: (C)

During break-in, piston rings and bearings need controlled loading to seat properly. Using a mid-range speed window lets the engine generate enough cylinder pressure and heat to promote seating without the excessive stress of high RPM or the insufficient load of very low speeds. Accelerating from about 50 km/h up to about 80 km/h provides the right balance: enough variation and load to help rings conform to the cylinder walls while keeping temperatures and stresses in a safe range. This range is more effective than starting too slowly, which wouldn’t create enough pressure, or jumping to very high speeds too soon, which can cause wear or glazing before proper seating occurs.

During break-in, piston rings and bearings need controlled loading to seat properly. Using a mid-range speed window lets the engine generate enough cylinder pressure and heat to promote seating without the excessive stress of high RPM or the insufficient load of very low speeds. Accelerating from about 50 km/h up to about 80 km/h provides the right balance: enough variation and load to help rings conform to the cylinder walls while keeping temperatures and stresses in a safe range. This range is more effective than starting too slowly, which wouldn’t create enough pressure, or jumping to very high speeds too soon, which can cause wear or glazing before proper seating occurs.