Gday guys,
Disclaimer:
This thred is designed to give a guide about the general accuracy of this product specific to my individual unit. Keeping in mind every instrument out there will have different results based on the QC of the manufacture and how it has been treated over its life. Myself Nor this forum will take any responsibility for the miss use of this information.
Aim :
To determine the accuracy of automotive instrument
Type:
EGT - Autometer 52mm, Cobalt 6945 series.
Range: 0 - 2000F (-17 - 1093c) with increments of 10F - 0.5%
Temp element: Thermocouple K-Type
Test instrument:
Fluke 744 Documenting Process calibrator. NATA certified & Calibrated 01/2013
Price:
Aprox $150 - 250 USD / AUD
Operator:
Myself - Qualified Instrument technical
Method:
The build quality and how the instrument has been treated in its life will usually determine its accuracy. The Fluke 744 process calibrator will be used to simulate known temperature values, and compared with what is shown on the gauge display & calculate the error. Will conduct a rising and falling calibration check in 50F increments from 0 - 2000 - 0
Note:
Current unit has been installed for aprox 6 months with around 10hrs of run time.
Calibration results
Note:
Have only documented the rising reference signal as the falling values were exactly mirrored (as expected)
Response time seems good - under 0.5sec between when the reference value was placed and instrument reflecting the reference.
Reference Temp Gauge Temp Error DegF Error %
0 0 0 0%
50 40 -10 20%
100 90 -10 10%
150 140 -10 7%
200 190 -10 5%
250 240 -10 4%
300 290 -10 4%
350 340 -10 2.9%
400 390 -10 2.5%
450 440 -10 2.3%
500 490 -10 2.0%
550 540 -10 1.9%
600 590 -10 1.7%
650 640 -10 1.6%
700 700 0 0%
750 750 0 0%
800 800 0 0%
850 850 0 0%
900 900 0 0%
950 960 +10 1.1%
1000 1010 +10 1%
1050 1070 +20 1.9%
1100 1120 +20 1.8%
1150 1170 +20 1.8%
1200 1220 +20 1.7%
1250 1270 +20 1.6%
1300 1320 +20 1.6%
1350 1370 +20 1.5%
1400 1420 +20 1.5%
1450 1470 +20 1.4%
1500 1520 +20 1.4%
1550 1570 +20 1.3%
1600 1620 +20 1.3%
1650 1670 +20 1.2%
1700 1720 +20 1.2%
1750 1770 +20 1.2%
1800 1820 +20 1.1%
1850 1870 +20 1.1%
1900 1920 +20 1.1%
1950 1970 +20 1.1%
2000 2000 (over range) n/a n/a
Conclusion
Unfortunately device only reads in 10F increments and not able to determine accuracy beyond its own resolution.
Between 500 - 2000 refects an accuracy of aprox +/- 2%. Slight loss of accuracy of device in low range below 500F. To most people would not be a concern if measuring EGTs at the exhaust port Unfortunately most automotive instruments lack the ability to correct any calibration/accuracy errors. Due to the market these instruments are aimed at (and priced to suit) it seems the manufactures cannot outlay the funds to develop the supporting electronics and/or software to be able to continuously recalibrate their instruments.
General Feedback
Bang for buck - Build quality of gauge feels nice and tight. Quality bright digital read out easy seen in day or night within peripheral vision. Simply unit easy to install and use, relatively well priced that has acceptable accuracy and response time above 500F.
Feel free to reply with feedback.
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