I have an EGT sensor with an 1/8 npt thread which requires an adaptor to fit it into the top of my tubular headers up-pipe.
At first I assumed it would be the same fitting as for the Lambda which is at the bottom but unfortunately not.
The socket size for the bung is 17mm and the threaded part is about 12mm and the thread pitch is the same as a subaru spark plug.
So that's the long way around asking if anyone has fitted a sensor into the boss at the top of the up-pipe on tubular headers and what was the adaptor size please? I think the headers are G2 type.
thanks
Trev

 

My Defi one was just MIG'd into place for £20.

HTH

dunx

 

The Boss fitting on my up-pipe is an M12 x 1.25 thread pitch, so finding an adaptor with a 1/8npt female wasn't a solution, concerns thin walls, metal suitability. There are sensors which fit direct.
The solution is to re-locate the lambda sensor to the top of the down-pipe, my simtek ecu doesn't use this and fit the egt sensor with a M18 adaptor to the lambda position at the bottom headers/up-pipe junction.
Trev

 

Sorry Trev but this is completely wrong. Your Simtek runs closed loop Lambda off boost. When mapping it is switched off to get the map close to the desired Lambda figure. It is then switched on to track Lambda and make trim adjustments so your Simtek does need the Lambda sensor to perform properly.

 

thought it used the O2 sensor at the bottom of the down-pipe, post cat?
Trev

 

On the New Age car and on MY93-96 the Lambda sensor is located at the collector before the uppipe and this sends a signal to the ECU. This sensor is often relocated to the downpipe just after the turbo to perform the same function. This is the narrow band sensor as supplied on the original car by Subaru and it is this that is used by the ECU.