The Pro II, Pro I-A, and the SC1000 data recorders each have a dedicated terminal for the connection of an exhaust gas temperature cable. Monitoring and relaying each of the EGT’s are done using components from three groups: the thermocouples, the junction boxes, and finally the cable that connects the junction boxes to the recorder itself. Each group is addressed here individually.

Exhaust Gas Thermocouples

Thermocouple probes are inserted into the header to measure the temperature of the exhaust gases as they exit the cylinder head. Racepak offers two types of thermocouples for this purpose, Bullet probes and Stinger probes. Bullet probes, a higher grade of thermocouple, are used exclusively on nitro-methane burning applications where there is a potential for detonation and temperature shock (extremely rapid changes in temperature). The Stinger probes are used on all other applications. Both types are available in two diameters, .250” for automotive applications, and .187” diameter for motorcycle applications. Thermocouples are attached to the header by means of a weldment bung that is welded to the header tube. The thermocouple probe is then secured at the desired depth with a compression nut and ferrule.

A selection of lengths for individual thermocouple probes, or prepackaged sets, are offered below. See the accompanying illustration for measuring instructions.

EGT Junction Boxes

Signal condition for the EGT thermocouples is provided within the conventional-style data recorders, making the need for separate signal conditioning modules unnecessary. But rather than routing up to eight individual thermocouple wires from the headers to the data recorder, we have provided these junction boxes to clean up the clutter. Each junction box is constructed to accept up to four thermocouple probes. A single divided-end EGT cable (see below) is then used to complete the connection with the data recorder. EGT junction boxes are numbered to help identify which cylinder each wire serves.

EGT Cables

The cable used to connect the exhaust gas temperature junction boxes to the data recorder are divided into two legs at the junction box end. The legs are 22” and 40” respectively from the split. This allows the cable to be routed along a frame rail on one side of the engine, with the longer leg of the cable being used to cross over to the junction box on the opposite side of the engine. To accommodate all routing methods we offer two different cables. Order the standard cable if the short leg of the cable will be attached to the box serving cylinders 1,3,5,7 (Chevy, Chrysler, & others), or 5, 6, 7, 8 (Ford). Order the reversed cable if the short leg will be connected to the cylinders on the other bank of the engine.

The overall length of this cable can be custom ordered in one foot increments between 8 and 15 feet. The overall length is measured from the recorder end to the tip of the longest leg.