Design, Fabrication, and Performance Evaluation of a Locally Developed Automotive Engine Test Bed Using a Hydraulic Water-Brake Dynamometer

Abstract

The high cost of commercial automotive engine test facilities limits access to reliable engine performance testing equipment in many Nigerian tertiary institutions, thereby constraining practical engineering training and experimental research. This study aimed to design, construct and evaluate a locally fabricated automotive engine test bed incorporating a hydraulic water-brake dynamometer. The test bed was designed for four-cylinder petrol engines with displacement capacities of 1.2-2.0 L, a design power absorption rating of 90 kW and a maximum design torque of 220 N·m. The supporting frame was fabricated from mild steel, while torque was measured using a strain-gauge load cell mounted on a 500 mm moment arm. Engine speed was measured using an optical tachometer, and temperature and fuel-consumption measurements were incorporated into the instrumentation system. The test bed was evaluated using a Toyota 7A-FE, 1.8 L, four-cylinder petrol engine under full-load conditions between 1,000 and 5,500 rpm and at different throttle openings at 3,000 rpm. The results showed a maximum recorded torque of 135.5 N·m at 3,000 rpm and a maximum calculated brake power of approximately 56.0 kW at 5,000 rpm. During part-load testing, torque and brake power increased with increasing throttle opening. The reported direct material cost was ₦286,500, excluding labour and overheads. The findings demonstrate the feasibility of locally fabricating an engine test bed for steady-state performance evaluation and engineering education. Further validation is required to verify fuel-consumption and efficiency calculations and to establish the test bed's full design capacity experimentally.