Crankshaft counterweighting — inline four-cylinder engines A typical in-line four-cylinder automotive crankshaft commonly uses how many counterweights (balance weights)?

Introduction / Context:
Counterweights on a crankshaft reduce bearing loads and vibration by balancing rotating and partially balancing reciprocating masses. The number and placement depend on engine design.

Given Data / Assumptions:

• Modern, production in-line four-cylinder passenger car engine.
• Four crank throws, 180° apart.

Concept / Approach:
An inline-4 typically has four crankpins. Many designs use two counterweights per crank throw (leading and trailing), resulting in a total of eight counterweights to reduce bending moments and improve smoothness.

Step-by-Step Solution:

Verification / Alternative check:
Crankshaft photos and parts catalogs for common inline-4 engines (1.5–2.5 L) show 8 counterweights, though some lightweight or older designs may use fewer as a compromise.

Why Other Options Are Wrong:

• 4: used in some older or cost-reduced designs but not typical for modern refinement.
• 12 or 16: excessive for an inline-4, more typical in multi-throw engines with different architecture.
• 0: two-stroke small engines may omit, not automotive inline-4.

Common Pitfalls:
Confusing balance shaft usage (to address secondary imbalance) with crank counterweights; they serve different purposes.

Final Answer: