PLANETARY GP 7G4244 - Caterpillar

to ensure that it will allow full governor travel.k) API gravity of fuel used. The power rating of the engine and the expected manifold pressure are based on fuel of 35° API gravity. If lighter fuel is used, the power output from the engine, and the speed range over which the manifold pressure will remain constant, will be reduced. If the fuel used has a specific gravity other than 35° API, refer to step 2 on page 11 to get the corrected horsepower.l) Proper operation of the pressure ratio control and the bypass valve. Test Procedure - Natural Gas Engines
The 4S6553 Engine Evaluation Test Group can be used to make operating adjustments on natural gas engines and to determine the approximate power output of natural gas engines.The manifold pressure gauge and differential pressure gauges can be used to make all the operating adjustments to the fuel system of natural gas engines. The tachometer can be used as a reference when making adjustments, but it is recommended that an accurate digital tachometer be used when taking critical speed readings.The manifold pressure gauge can be used to make an approximate setting when balancing the manifold pressure in the two banks of a V-type engine. One needle can be connected into each bank to read the pressure in both banks. As the accuracy of this gauge is marginal for the final setting, it is recommended that the banks be balanced as closely as possible with the manifold pressure gauge, and then one of the differential pressure gauges be used for the final adjustment. The differential pressure gauges can be used for making all of the carburetor and regulator adjustments. Use of the 3B9389 Fittings at the test ports will speed testing by permitting switching of the gauges between ports without the need to shut off the engine. See the appropriate Operation Guide and Service Manual for test port connections, procedures and proper values.The power developed by a natural gas engine, either naturally aspirated or turbocharged, can be determined from the manifold pressure (boost), temperature of the air-fuel mixture in the manifold, and the BTU content of the fuel. Always measure the manifold pressure under the carburetor butterfly for all horsepower calculations. This power determination is accurate only for an engine in good condition with all adjustments correct. Under laboratory conditions, accuracy as close as 3% is possible. Under field conditions, accuracy may be less.Use the following procedure to check the power output of a natural gas engine.1. Run the engine under load until it is at operating temperature. Make a record of the following information at full load speed. Inlet manifold pressureEngine speedAir inlet temperatureAir inlet restrictionExhaust back pressureFuel delivery pressure2. Refer to the charts on pages 24 through 37 of engine horsepower vs. manifold pressure (under the carburetor butterfly) for the engine being tested to determine the power developed by the engine under standard temperature conditions using 1000 BTU per cu. ft. natural gas for fuel. These charts