In an EGR engine, the piston stroke length is often longer than in the same model without EGR; the other technician claims it has nothing to do with EGR, and some EGR engines have shorter strokes than non-EGR models. Which answer reflects both technicians’ view?

• A. Both Technicians
• B. Technician A only
• C. Technician B only
• D. Neither Technician

Answer: (A)

Stroke length is fixed by engine geometry and design choices, not dictated by EGR. The piston travel is set to meet displacement, compression ratio, and torque goals, which can lead to longer or shorter strokes depending on the model. EGR’s role is to recirculate exhaust gas to reduce NOx and control combustion temperature; it doesn’t impose a universal rule about how long the piston’s stroke must be. As a result, some engines with EGR have longer strokes than their non-EGR counterparts, while other EGR engines have shorter strokes. Because both scenarios can occur across different engine designs, both technicians’ views can be true in different contexts. Therefore, recognizing that the real-world relationship varies with the specific engine design makes the option that both technicians are correct the best choice.