Exhaust Gas Temperature (EGT) readings using thermocouple sensor type k

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Exhaust Gas Temperature (EGT) readings using thermocouple sensor type k

Postby ArT » Mon Aug 24, 2015 11:13 pm

Measuring Exhaust Gas Temperature (EGT) is more and more popular specially in modified engines. It's quite simple modification. The most popular solution is based on k-type thermocouple sensors, thermocouple amplifier and measurement instrument.

What exacly is needed for EGT measurements?

  • temperature sensor - any thermocouple type "K" or thermocouple type "K" from inconel (recommended for high load petrol engines)
  • thermocouple amplifier, e.g. EGT-K - signal from thermocouple is really small (in milivolts) and it is not linear. Thermocouple amplifier converts this signal to 0-5V linear output,
  • measurement instrument, e.g. UTCOMP or UTCOMP-PRO or any ECU for tuners (e.g. AEM EMS, GReddy e-MANAGE, Motec, Stack, ACR systems, HRC)

EGT-K is available in single (1), dual (2) or quad (4) channel version, it's compatible with any type-k thermocouple and measure temperature in range of 0-1250 Celsius degrees. In most cases single channel (1 sensor) is enough but sometimes it is necessary to measure temperature for each cylinder so it may be needed 4 sensors or even 8 sensors (and 2x 4ch. EGT-K) for 8-cylinder engine.

UTCOMP can read signal from EGT-K and show temperature on display. You can set also alerts for to high exhaust temperature. It has also data logger feature.

How to connect thermocouple sensor?

Each thermocouple wire has a positive lead and a negative lead. Connect the positive lead of the thermocouple to the TC+ terminal and the negative lead of the thermocouple to the TC– terminal. There are few standards for wire colours but in most cases there are yellow (+) and red (-) OR red (+) and white (-) OR green (+) and white (-) OR red (+) and black (-). If you are unsure which of the thermocouple leads is positive and which is negative, check the thermocouple documentation.

Source: http://www.pyromation.com/Downloads/Data/ColorCodessheet.pdf
thermocouple-type-k_wire_colours.jpg (55.25 KiB) Viewed 14249 times

If you connect it wrong to EGT-K, there is no risk for damage but readings will not work. Please note: if you have shielded thermocouple (or any wire of thermocouple is connected to other metal) than you have to connect negative wire to common ground. If you do not do this than readings will be incorrect and unstable. You do not have to do this when both thermocouple wires are isolated from other conductive materials.

How to assembly thermocouple sensor?

You should use some kind of compression lock, please check example below for 3mm or 5mm thermocouple:
egt-compression-lock-5mm.jpg (7.72 KiB) Viewed 7400 times

egt-compression-lock-3mm.jpg (9.25 KiB) Viewed 7400 times

Inside compression lock is small olive/barrel from soft material which will seal connection when you tighten the nut. External thread (usually 1/8" NPT) should be assembled nearest cylinder head (e.g. in exhaust manifold), but for turbo engines it's recommended to assembly it after turbo from safety reasons. It's recommended to clean (degrease) surface of the probe before clamping compression lock. If possible the end of measurement tip should be in the center of pipe. It's also recommended to stretch the spring at the exit from the probe because it protects cable against breakage.

How to set Exhaust Gas Temperature (EGT) measurement in UTCOMP gauge?

First of all, you need to connect EGT-K output to any 0-5V analog input in UTCOMP (AdcX) and configure input in UTCOMP application:
egt-settings-in-utcomp.jpg (155.84 KiB) Viewed 16458 times

Secondly, you need to configure EGT reading. Go to advanced settings and provide calibration data for EGT-K:
a = 250.0, b = 0.0
egt-k_calibration-settings-in-utcomp.jpg (62.01 KiB) Viewed 16458 times

Finally, you can set customs alerts :-)
egt-alerts-configuration.jpg (74.97 KiB) Viewed 16458 times

EGT-gauge-display.jpg (35.19 KiB) Viewed 16458 times

Full description of EGT-K is available here.
Full description of UTCOMP and UTCOMP-PRO is available here.

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