Dabear
I have a D180 mounted on an Australian Warbird fitted with a P & W R 985 Radial engine (9 cylinders). Up to now I have been monitoring cylinders (2, 3, 5, 6, 8, 9,) which works fine but obviously does not give you the complete picture.
I am rewired my DYnon CHT/EGT Harness terminating all of the junctions in the engine bay area with gold pinned connectors and have a switching arrangement for cylinders 7-9,
I have used three 12 Pin Connectors arranged as follows:
1. Cylinder 1-3 CHT /EGT T/C thru Connector direct to DYNON
2. Cylinder 4-6 CHT/EGT T/C thru connector to Multi Pole Rotary SW to DYNON as 4-5-6
3. Cylinder 7-9CHT/EGT T/C thru Connector to Multi Pole Rotary SW to DYNON as 4-5-6
Background to Connectors:
I am using three hi quality connectors rather than “Faston Type” connectors for two reasons- Firstly whenever you create a join in T/C wire you create “in effect” another mini T/C unless you are using similar materials. If you’re wiring joins are inside the cockpit area the temperature variations as not large and the errors produced are small. If your connectors are in the engine bay area, tempt variations can be quiet large and variable depending upon location of joins, as will the tempt variation of CHT (25C). I have used the connectors to make all of the connections more “thermally stable” and the same Tempt as they are located together and I am routing some cooling air to minimize thermal variations. Additionally I can reverse 4-6 & 7-9 connectors and have a hard wire solution to monitoring on alternate flights if my SW arrangement fails
From my experimentation and test flying so far, the system works finie, however the following points should be noted.
It is important to keep joints and connections to a minimum and always use the same connection materials on both sides of all T/C joints as this will cancel out errors on either side of T/C Junction. Use the same Brand /Spec wire for any changes as this will also reduce errors.
Wire connection to rotary switches can be a problem as crimping not generally possible. Siver Soldering is the next option (not ideal) and very difficult with K type wire CH/AL.
Try to keep all connectors at the same tempt & materials common.
Try OMEGA in USA for rotary selector switches especially for this purpose.
I have used Westac EGT/CHT senders (ie 2.5" clamp-Ktype & 18MM Rings J type) and these work fine.
I hope this helps regards
Ron 777