Engine Dynamometer - Install Engine (14-01) Section 14 - Engine Testing - Group 14 M11 Page 14-24 The air flow piping requires 4 inch I.D. aluminized steel piping. The flow circuit must have as few bends as pos- sible maximizing the length of straight sections. However, when bends are required, use long elbows. Do not use mitered elbows, or anything that changes the air flow direction quickly. To reduce intake air restriction, air flow direction changes must occur gradually. During engine test monitor the pressure drop through the remote aftercooler. Install one end of a manometer to the Compuchek fitting in the turbocharger compressor outlet elbow.
Install the other end of the manometer to the Compuchek™fitting in the intake manifold. Although less accurate than a manometer, two individually calibrated press (in Hg) gauges can be used to monitor pressure drop. The pressure drop between these two locations must not be greater than 102 mm Hg [4 in Hg]. If the pressure drop is greater than 102 mm [4 in Hg], check the remote af- tercoolers and air flow piping for plugging. Clean and replace if necessary. During engine test, also monitor intake manifold tem- perature. Install a thermocouple (Fluke) in the 1/2 inch pipe tap in the intake manifold.
The intake air heats up as it passes through the intake manifold so the temperature must be measured as close to the intake manifold elbow as possible. If the intake manifold temperature exceeds 66°C [150°F] during the test, make sure that there is an ample supply of clean cool water flowing through the aftercoolers. Un- der no circumstances must the intake air temperature be allowed to exceed 77°C [170°F]. Visually inspect the engine for coolant leaks. Repair all leaks found.