Testing of Constant Speed Internal Combustion Engines According to Indian Standard.

Today in this article I will discuss the Testing of I.C engines according to Indian standards 1600-1960. 

Testing of Constant speed Internal combustion engine-

This cycle is applied to testing of constant speed, reciprocating internal combustion engines of the following types used for general purposes :

1. Compression Ignition Engine- 

A compression ignition engine is a type of internal combustion engine in which ignition of the fuel-air mixture occurs without the use of a spark plug. The fuel-air mixture is injected into the cylinder during the intake stroke, and compressed by the piston during the following compression stroke. This high temperature and pressure environment cause auto-ignition of the fuel, which initiates combustion without the need for a spark. Compression ignition engines are also known as diesel engines, after one of the most common types of fuels used in this type of engine. Other fuels that can be used include biodiesel, ethanol, and natural gas. One advantage of compression ignition over spark ignition engines is that they are typically more efficient in converting fuel to energy. 

2. Carburetor Type Engine- 

Carburetor type engine means the Spark ignition engine. It is called a carburetor engine because the air-fuel mixture is compressed into the carburetor before being fed to the cylinder. This air-fuel mixture is ignited at the last of the compression stroke. The combustion process is held in the cylinder with a spark of the dark plug.

3. Gas engines- 

A gas engine is an internal combustion engine that runs on combustible gas, such as natural gas, propane, or butane. Gas engines are used in a variety of applications, including cars, trucks, boats, and other vehicles. They are also used in industrial applications such as generators and pumps. Gas engines are typically more efficient than traditional gasoline-powered engines, making them an attractive option for many applications. Gas engines are also a type of internal combustion engine. 

General requirements for the test- 

The manufacturer shall supply the performance characteristics of the engine prior to the commencement of the test. The engine shall be tested as offered to the purchaser. All parts shall be in stock and all parts essential for engine operation shall be included. Accessories used on the engine under test shall be listed.

Preparation for test- 

The engine shall be completely stripped and examined physically so that design features and also the condition of the various parts may be noted before the tests are commenced. After the physical examination, the dimensions of the main working parts, listed below, shall be checked and
recorded :

(a) Cylinder head,

(b) Valves, valve seats, valve springs, and valve guides,

(c) Cylinder liners,

(d) Piston assembly,

(e) Connecting rod, small end and big end bearings, and comic no and 1.

(1) Crankshaft, including bearings and journals,

(g) Governor springs.

The engine shall then be re-built by the manufacturer and mounted on a suitable test bed. It shall be run in such a manner and for such a period as recommended by the manufacturer. After the run, the engine oil shall be changed according to normal practice. The valve and ignition or injection timings shall be checked with the manufacturer’s specifications. The grades of fuel and lubricating oil used shall be those recommended by the engine manufacturer.

Preliminary run- 

The engine shall be subjected to a preliminary run of 49 hours at rated speed under operating temperatures as specified by the manufacturer, in non-stop cycles of 7 hours each, conforming to the following cycle, the period of each run being a minimum one cycle :

Load Running Time(hours)
25% of the rated load 1*1/2
50%of rated load 2
75% rated load 1*1/2
100%of rated load row4 col 2

During the preliminary run, special attention shall be paid to engine vibration and quietness. The oil pressure shall be checked from time to time. Oil, coolant, and fuel leaks shall be rectified and faulty components replaced as may be found necessary. A complete record of such attention and of the running time of components changed shall be kept. After the preliminary run, the performance test shall be conducted in accordance with the methods described in IS 1601-1906.

Performance Test According to 1600-1960(Indian Standards)- 

The complete performance test for a variable-speed engine will comprise the following determinations at suitable speeds over the engine speed range of the engine specified by the manufacturer.

(i) At each suitable speed :

 (a)Maximum BP

 (b) Maximum torque

 (c) Frictional power

(ii) Specific fuel consumption at 100, 80, 60, 40, and 20% of the maximum load at the corresponding speed.

(iii) Fuel consumption rate in grains per hour at no load and minimum speed.

Preparation for test- 

Test runs shall be made on an engine as being offered to the consumers. Before starting the tests, the engine shall have been thoroughly run in, and the fuel and lubricating oil used during the test shall be specified by the engine manufacturer. In general, the engine operating temperatures and the lubricating oil pressure during the test shall be maintained at values recommended by the manufacturer. The Test procedures are- 

Engine adjustments- 

The distributor, carburetor, or fuel pump rack, as the case may be, shall be set at its nominal specified value at idling in contrast to its nominal adjustments for maximum power at each speed.


The temperature of the inlet air shall be measured at the entrance of the induction system.

Number of runs- 

In every test, a sufficient number of runs shall be made throughout the speed range. A run shall be made at the lowest steady speed at which the engine operates.

Duration of runs- 

Performance data shall be obtained under stabilized operating conditions. The duration of the experimental run depends upon two principles :

(a) No data shall be taken until load, speed, and temperature have been stabilized.

(b) Recorded data shall be average sustained values maintained over a period of at least one minute, with no significant change occurring during that time.

Power test- 

For all power tests with results to be plotted versus speed, a single series of stabilized runs at ascending speed is sufficient. This series of runs should progress continuously from the lowest to the maximum. If the engine requires to be idled between runs to avoid excessively high temperatures, sufficient time should be allowed for the engine again to reach its stabilized condition before taking the reading.

Engine speed- 

Engine speed should be held as constant as possible by means of applied dynamometer load at wide open throttle, or by throttle adjustment at part load. 

Friction power- 

The friction power test shall, if possible, follow immediately after the power test. If this is not possible the test shall be conducted under conditions similar to those for the power test. 

Fuel consumption- 

Fuel consumption shall be measured simultaneously with brake power. The fuel consumption measurement shall not be started until the engine is stabilized. A measuring interval of not less than 60 seconds shall be used when measuring speed and fuel consumption. All specific fuel consumption figures shall be based on observed brake power. 


1. Obseved brake power is given by  Bp=(F-s) 2πN (R-r)/60
2. Mechanical Efficiency,  n= BP/IP
3. Indicated power- IP= BP+FP
4. Specific fuel consumption- specific fuel consumption shall be computed on the basis of a gram of the fuel per observed brake power hour. 
5. Five hundred-hour endurance test, after completion of the performance test, the engine shall be run for 500 hours at rated speed, in cycles of 16 hours of continuous running, each cycle being made up as follows:

Load Running Time(hours)
100% of the rated load 4(including warm-up period
50%of rated load 4
110% rated load 1
100%of rated load 3*1/2

At the end of each 16-hour cycle, the engine shall be stopped and necessary servicing and minor adjustments may be carried out in accordance with the maker’s schedule. Before starting the next cycle, the engine shall have reached very nearly room temperature. The engine shall be topped up with engine oil if required, and the quantity consumed recorded. In case the duration of the endurance test is longer than the period of oil recommended by the engine manufacturer the oil shall be changed according to the manufacturer’s time schedule. The amount of make-up oil used during the test shall be used to establish the oil consumption rate. One liter sample of the oil drained during each oil change and a one-liter sample of the fuel used shall be sent to the laboratory for analysis. The power and fuel consumption shall be determined by repeating the performance test. 

At the conclusion of the test, the engine shall be stripped, its condition noted and the dimensions of the main working parts checked and recorded. 

Also, read-

What is the Indian Standard act 1600-1960?

Indian Standard act 1600-1960 is a code for testing the Internal combustion engine under various conditions. 

What is mechanical Efficiency? 

Mechanical efficiency is the measurement of the effectiveness of a machine, converting the energy supplied to useful work. It is defined as the ratio of the output work done by the machine to the input work supplied to it, expressed as a percentage.

What is Indicated power?

Indicated power is a measure of the power output of an internal combustion engine, calculated from the engine’s pressure and volume changes during a complete cycle of operation. The maximum potential output of the engine, assuming 100% thermal efficiency. Indicated power is used in engine design and analysis to determine the size and performance of an engine, and to assess its potential for improvement through modifications or optimization. It is expressed in units of horsepower or kilowatts.

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