Product category:
Testing, analysing and monitoring equipment
News Release from: Labcell | Subject: M400MR multi-range blow-by meters
Edited by the Engineeringtalk Editorial
Team on 20 January 2006
Prodrive buys blow-by meters for engine
test cells
Prodrive Automotive Technology has bought three M400MR multi-range blow-by meters from Labcell for use in its engine test cells.
Prodrive Automotive Technology has bought three M400MR multi-range blow-by meters from Labcell for use in its engine test cells Compared with the previous method, the instruments are easier to use, faster, more accurate, and result in some engine tests being completed more quickly
Blow-by refers to the passage of combustion gases past the piston rings and valve guides to the crankcase.
It gives an indication of engine wear and lubricant performance, and is typically measured at the start and end of an engine test sequence.
In some cases, however, numerous measurements will be made throughout a test.
Traditionally blow-by has been measured by connecting a gas flow meter between the crankcase and the inlet manifold (from which the gases are normally ingested back into the engine for recombustion); measurements would be taken by an operator watching a totaliser on a flow meter and using a stopwatch to time a 30s period - the normal time over which engine measurements are made.
This procedure is labour-intensive, tedious and subject to human error.
Furthermore, the result has to be manually logged, then transferred to the PC-based reporting software package used to gather automatically most other test parameters.
In contrast, the digital M400MR instrument can be connected to the data acquisition (DAQ) system by a standard BNC connector.
Measurements can be automatically taken upon receipt of a signal from the PC-based software running the test, and the instrument - which is configurable via the RS232 serial link - can be set to take a flow rate measurement over a 30s or other period and calculate the average before transmitting this back to the DAQ system.
Suitable for measuring blow-by on spark-ignition or compression-ignition engines, the M400MR operates using the vortex-shedding principle that gives fast response, assures zero stability and is insensitive to the temperature, pressure and viscosity of the blow-by gases.
There are no moving parts so the instrument is easy to clean and service, as well as being reliable.
Accuracy is 1% and repeatability 0.5% of reading, with the operating mode either being as a flowmeter or a flow totaliser.
In one application to develop an engine crankcase breather, Prodrive used the M400MR and reduced the time required to perform a full set of readings by 50% from around two hours to one hour.
Brian Whitby, the Test Engineer using the instrument, said: "We have been using the M400MR instruments for around three months solidly and the operators love them".
"They are so much easier to use, quicker to set up, and simple to transfer from one test cell to another".
"We are definitely saving time by using them, and the comprehensive comparison tests that we ran before purchasing the units gave us full confidence that they are as accurate as the old method".
"Moreover, the digital output saves us having log data manually; instead we just press the logging button and the instrument does the rest".
"It also enables the actual reading to be displayed in real-time on the same screen that is showing other values, which is a huge advance over watching a flowmeter and a stopwatch".
Prior to ordering the instruments, Prodrive had a unit on loan.
This let the company run trials on all sizes of engine from those suitable for small hatchbacks to powerful V8 engines and large capacity diesel engines.
These tests showed that the methods were within 1 litre/min, which is close enough given that an engine running at a constant speed will typically show a blow-by that fluctuates by 2 or 3 litre/min.
Almost every engine tested is subjected to a blow-by test at the start of a test programme to check the internal breathing; a second test is usually run at the end of the test sequence to give a comparative reading.
Such tests would normally be run over one minute, though an engine with little blow-by may be tested over three minutes to give a more accurate result.
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