EGT point Pre Turbo 2003 GU

Just as an aside how did the readings compare before and after you spliced it in.
My Autometer model specifies that NO MODIFICATION should be done to the wiring at all as it has been correctly calibrated at the factory. Any modification may result in incorrect readings.
Definitely shouldnt be cut to length just rolled up and secured.

G'day Graham,
No I didn't cut/alter the wires in any way. I mounted the DPDT switch on top of the plastic case that the gauge was mounted in and took the ends of the thermocouple directly to the switch inputs. Then I connected the switch to the input terminals on the back of the gauge....about 2" of additional cable.

I checked with Ian at Thermoguard before I did it (he supplied me with the extra thermocouple and knew what I was planning to do).

The Patrol has been "gone" from grasp for almost 2 years now, but the memory of seeing the manifold reading around 560oC going up the freeway out of Adelaide, while the dump pipe was showing about 350oC, will live long in my memory. The manifold also reacted much more quickly than the dump pipe.

Roachie

Hi Gents,

If I may put in my two cents worth?

Graham, I don't have a lot to do with analog dial type EGT gauges/pyrometers (mine are electronic digital types), but I believe the very small thermoelectric voltage from the thermocouple has to drive the moving-coil meter movement directly. This means the impedance of the extension wires between the thermocouple tip and the meter is significant in the overall loop impedance. That's why, I believe, Autometer, VDO, etc. say not to cut or join the wires but just to coil-up any excess.

In industry, thermocouple leads may be anywhere from a few cm to over 100 m in length. But they are connected to electronic instrument amplifiers with extremely high input impedance and cold-junction compensation (as in my kits) and the lead impedance becomes insignificant. So, provided the correct thermocouple and extension cable are used (generally type-K for EGT applications), the leads can be any length.

Now, as Roachie says (How are you? I haven't been on here for a while), with an electronic gauge it's quite feasible to switch between two (or more) thermocouples provided the job's done correctly. All the wiring must be done to a high standard as were dealing with very small voltage levels. All the thermocouples need to be terminated as close as possible to the digital indicators input terminals (so the cold-junction compensation will still work).

Between the lead terminals, the switch and the indicator terminals, ordinary copper wire can be used and can be any practical length. (That is, while all Roachie's wiring is very close to the indicator terminals, it is possible to have the selector switch some distance from the indicator). As well as Roachie's installation, I supplied a couple of other dual-input systems, some for dual EGT/Coolant temp as I have in my vehicle.

Hope this was of interest. Ian.

Then buy your EGT kit here for about $206 posted against $350 for exactly the same one locally
They are good to deal with and send the stuff quickly. I bought an Autometer 5744M (Metric)
Make sure you ask for the metric model the one pictured is a Farenheit model but the text is correct

http://www.atlanticspeed.com/productcart/pc/viewPrd.asp?idproduct=5119
If you want a black faced one they have them as well just do a search on the site. It comes with thermocouple and all fittings.
Shown is a pic of mine mounted in a pillar pod in my Croozer

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