EGT Installation

Here are pictures of the holes that I drilled and tapped while I had my head off of the car. Read on from some facts, and answers to common questions regarding EGT gauges on GLHTs and TDs in general.

An Exhaust Gas Temperature gauge is used to mesure exhaust gas temperature as it's name impies.

Our motors tend to typically run hottest in the #4 cylender, so that is where I would reccomend placing the probe. NOTE: According to several well respected turbo dodge owners with 4 probe EGT gauges, the #3 cylinder tends to run hottest in their cars. This could be caused by the fact that most people running stock exhaust manifolds tap the #3 cyl. where it sees gas from other cyls. as well, and therefore produces a hotter reading. As the second picture at the top of the pages shows. I have a hole tapped for the #3 and #4 runners so I can do some testing on my car to see which cyl. runs the hottest. Most gauges will use a type K thermocouple which threads into a hole that is in the manifold. Ideally you would want this hole to be about 1-1/4 in. from the head. The probes are most often a compression style fitting, so you can intall the probe while the head is still in the car by drilling your hole with your appropreate size bit, and tapping the hole. The compression fitting will allow you to place the probe at the depth you need, as many of them are too long for full penetration into the runer from the side. The gauge takes the reading from the tip of the thermocouple, so make sure that it is not touching the wall on the opposite side of the runner, as it will read much lower than it actually is.

Most of the fittings used will be a 1/8th-28 NPT fitting. I would reccomend using a magnet, and drilling slowly to catch most of the metal shavings that result from drilling the hole. When tapping you could just use a little bit of grease on the tap to capture most of the shavings.

I would shoot for about 1450*F-1500*F. Some people (Read Gary Donovan) have run much higher EGTs that this, but the typical motor SHOULD be safe at this level. Each motor is different however, so I would keep a close eye on things and check you plugs regularly to ensure everything is looking good.