Intake Temperature Monitor


Why install one of these?

To find out what sort of intake temperatures you are experiencing. It will also show you the effects of Water Injection and the effects of turbo charging...

It will also give you a reassuring indication that your WI is working correctly. It will also help you to size the WI jet, so that you fit a suitably sized nozzle.

Why am I interested in knowing the temperature?

Compressing air results in the air temperature rising. Remember pumping up your tyres on your bike when you were a kid, and how hot the pump got? Well, a similar thing is occurring when the turbo compresses air.

So, turbo charging results in the intake temps rising. An intercooler will reduce these temperatures, and can be assisted with the use of Water Injection.

If the intercooler cannot sufficiently cool the intake temps and they rise beyond a "safe" temperature then there is a real risk that the mixture entering the cylinders can be ignited prematurely, resulting in detonation - click here for an article on "det".

What is a "safe" temperature?

Hmmmm...debatable. In my humble opinion 40oC is a reasonable temperature to aim for, and should be fine. Temperatures exceeding 60oC are bad and should be avoided, (in my opinion of course!).

What sensor have you got?

I have fitted a sensor and LCD screen, purchased from St Albans Car Clinic, you can contact them on (01727) 867747 and e-mail them here. It costs 50 and comes with the sensor and a green backlit LCD screen. I now believe that this same sensor and screen is available from RS components

** Update 24/03/06 - St Albans Car Clinic are no longer able to supply this temperature gauge **

Is the sensor any good?

Yes, been on the car for 18 reliable months. The sensor is small and robust, (unlike other examples I have seen), and the screen is large enough to see, but small enough to mount in numerous locations. The temperature reading also appears to be accurate.

Ok, anything else to consider?

My primary consideration was to fit this directly in the air path and after the IC and after the WI nozzle, to see the effects of WI and the temperature of the air charge entering the cylinders. There's not much point in placing a sensor in a blocked off hose or placing it in an area that's not directly in the air path, is there? You just won't get accurate readings.

The temperature range is ~-10 to 70oC and reads is 0.1oC increments. The refresh time of the screen for temperature change is more than adequate.

How did you fit it?

You aren't going to like short I removed the intake manifold and drilled and taped a hole for it...bear in mind the point I made above.

My probe is mounted in the intake manifold. I drilled and tapped the side of the manifold to accept the sensor. Note that the sensor is directly exposed to the intake air charge. DO NOT drill and tap the manifold without removing the manifold from the car, it is highly likely that swarf will enter the engine via the intake and damage the engine and/or valve train
  The sensor requires an 1/8NPT hole/thread. However, the sensor body is plastic and may fit an appropriately sized hole in some thin material...try a 8.5mm hole
  It may be possible to remove the blanking plug on the side of the manifold...
Note that the sensor is housed in a grey plastic body. The body is constructed so that air can pass through the plastic and over the sensor and then out. Here the outlet has been blocked off by some hose
Next, mount the display in a suitable location. As you can see the display is small and compact and will look neat and tidy in lots of places. The plastic surround for the screen was homemade and is necessary to shield the display from sunlight, or it may be difficult to read
  The screen requires an ignition 12V, earth and the connection to the sensor...
The screen is permanently backlit


This article is intended as a helpful guide as to how I fitted an intake air temperature monitor. If you are in any doubt, or not qualified, do not undertake this modification. Always consult a qualified mechanic.