Installation information:

Exhaust Gas Temperature (EGT) Probe placement in the exhaust path requires special attention. If it is closer than 1½ inches to the cylinder head, probe life will be limited, too far away the probe will be less responsive. Should there be doubt concerning in which exhaust tube or specific placement of the probe, you should check with the engine manufacturer or your engine builder.

There are two basic ways EGT probes are installed in multiple cylinder engines either for monitoring a bank cylinders or each individual cylinder. Monitoring a bank of cylinders give you information on the over all exhaust gas temperature generated by the cylinder bank.

For example when installed in a "V8" cylinder engine two EGT probes are used. Each probe is place in the exhaust header collector just past the point where tubes from one side become common. The probes are connected to high temperature thermocouple wire and a connector and then to a dual channel meter for monitoring. This gives you the average temperature of the four cylinders in each bank keeping the ability to gather the necessary temperature information simple.

You may consider installation of probes in all cylinders for more exact tuning requirements. Again, proper installation and placement of the probes is very important in order to get reliable readings.

EGT systems are not complex or expensive to install.

An advantage of the EGT monitoring verses monitoring the cylinder head temperature is the close to immediate response to change in temperature verses the fuel to air ratio. The peak or point of maximum temperature is the basic reference for performance management. If you have experimented with the exhaust gas temperature sensors at the engine builder’s dyno or engine manufacturers recommended maximum horsepower, you have observed during the tuning process results in the peaking of the exhaust gas temperature via the gradual leaning of fuel and air ratio adjustments. The peak temperature in each cylinder will vary with different power settings, changes in altitude, and ambient temperature. So tuning for specific atmospheric conditions can be critical on race day.

Typically a hand held digital readout like the dual channel or single channel meters The Sensor Connection offers will have the ability to read individual cylinder exhausts or cylinder banks. Multiple channel data acquisition systems will gather and display data from all exhaust port temperature readings simultaneously. The requirements for precision of the data collection of your application will determine the type of data collection system you will need.

Tuning the fuel to air ratio for peak efficiency with an EGT Probe

From the peak EGT, either increasing or decreasing the fuel to air ratio causes a decrease in EGT. Richer than peak EGT cooling occurs because there is excess fuel, and leaner than peak, cooling occurs because there is excess air. So you must have a basic idea of where you are starting from regarding base cylinder exhaust gas temperatures and rich or lean condition of the fuel delivery system.

Peaking exhaust gas temperature (EGT) with a carbureted engine is frequently a vague point because of less efficient atomization compared to electronic fuel injection to the individual cylinders. As a result, carbureted engines tend to operate smoother at +25 degree +50 degree F on the rich side of peak exhaust gas temperature (EGT).

Fuel injected engines typically provide a more precise peak exhaust gas temperature, therefore the EGT system is likewise a more precise method of performance tuning with fuel injection.

A simple definition of peak EGT is the chemically correct mixture of fuel and air, which gives 100% utilization of all the fuel and all the air.

Benefits of EGT sensors for engine tuning:

Operation at peak EGT, particularly on long runs like in road racing or circle tracks, will give a fuel savings meaning less pitting for fuel (increased range) as well as less likelihood of spark plug fouling.

Temperature variations will occur between in between individual cylinders when using a probe for every cylinder. Typical variations of about 100 degree F between each individual cylinder can be observed with fuel injection systems, and about 200 degree F with conventional carburetion. Carburetion variation is greater because the atomization of the fuel is not as effective when compared with fuel injectors. In colder air temperatures, the mixture atomization is poorer for both fuel injected and carbureted engines. However, with the carburetor, the fuel/air ration and atomization is less effective resulting in larger temperature variations when comparing individual cylinders.

Tip: Tuning for Power

When tuning for power typically it is in the range of plus 100 degree F on the rich side of peak temperature. It is generally not considered a practical economic fuel / air ratio for cruising purposes.

Tip: Tuning for Economy

If you want to tune for economy, care must be taken not to create an excessive lean condition can cause detonation and/or pre-ignition resulting in possible engine failure. Damage is caused by maximum leaning in higher engine rpms.

Advantages and benefits of an exhaust gas temperature (EGT) sensor / probes

Operation at peak EGT, particularly on long runs like in road racing or circle tracks, will give a fuel savings meaning less pitting for fuel (increased range) as well as less likelihood of spark plug fouling.

• Aids in making proper adjustment to the fuel / air mixture ratio
• Increased precision in fuel and performance management.
• Gives you the ability to tune for fuel economy
• Decrease in fuel stops.
• Detects some types of engine troubles.
• Aids peak engine performance at cruising speeds.
• Help to prevent spark plug fouling.
• Fits any internal combustion engine.

Why use Thermocouple EGT probes from The Sensor Connection?

We have technically trained staff to help you select the right exhaust gas temperature sensor for your application. We specialize in these hi perfomance thermocouples for racing, R&D and Test labs. [more]