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EGT Position


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I'm finaly making plans to fit the Def front end to my engine and also fit the uprated watercooled turbo that I've had sat on the shelf for about 2 yrs.

The problem is I also want to fit an EGT before it gets fitted.

I have 1 of these from Si R


To fit to 1 of these


The problem is which position is better or easier to fit. Can you drill tap the manifold and put the brass boss into the manifold direct or does it need a boss brazed in and then the brass boss screws into that?

Anyone local to Warminster or Maidstone know of anyone with the skills/tools/time to do the job for me. I have a big packet of hobnobs or beer ;)

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My probe (that word always makes me snigger....) is about 2 inches from the head in the manifold closest to the bulkhead (Number 4? I can never remember...)

Mine came with a steel boss so I welded that to the manifold and screwed the probe into that.

I'd be inclined to get a tap the same size as the boss and drill / tap the manifild. That way, if the thread on the soft brass gets damaged the probe will still be usable.

I could help out with it if you get stuck.....

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Thanks for that advice. How much can you bend the thermocouple? There must be a point when it gets to bent and won't function properly. I'll have a word with a mate in Kent and see what he knows

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You need to ask the man who supplied the probe how much it will bend. The radius of the bend is as important as how many degrees it goes. The probe I use came from Kalestead and is bent through 90 degrees, and the radius was just what felt comfortable to me, as it bent in my fingers.

Regarding placement, there will be different opinions.

With a petrol engine the manifolds have long primary pipes, made of thin material that looses heat quite rapidly, so the hottest point is any exhaust valve. Thus the probe is positioned with the tip almost poking into the port in the cylinder head. However, note that it only gets hit with one burst of very hot gas every 720 degree combustion cycle. For most of that 720 degrees it's 'cooling down' (the term is relative). Thus the temperature is an average value, something under the peak value.

Manifolds on turbocharged diesel engines have short primaries, and are made of thick material that doesn't lose heat as quickly. If you can place the tip of the probe where it is wiped by each exhaust pulse, there is no cooling off period, and the temperature is shown more accurately.

In the positions you have shown, one only sees a single exhaust pulse, the other might see two pulses, but more likely one. I would be looking to put the tip of the probe on the turbocharger side of the turbocharger to manifold joint. You might be able to mount the probe in the manifold, and by bending the probe, position the tip in the right place. Or go through the turbocharger housing, in that short stub of pipe between the flange and the rotor housing.

Alternatively, can you get in from underneath the manifold (as you have it positioned) so the tip is pointing directly along the line of the airflow into the turbocharger, the tip being level with the join?

Just because the manifold and the turbocharger housing look like manky cast iron, don't assume this is the case. My BMW manifold looks exactly the same, but when I came to drill and tap it, the drill and tap cut it like butter, and the cut edge was beautifully shiny, displaying a high nickel content. The Kalestead probe didn't come with a big brass adaptor that you show, just the smaller adaptor and gland nut. I thus tapped the manifold for the small adaptor, which is probably stainless steel. Using just the small adaptor makes it easier to place in the manifold or housing.

Hope this helps.

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Thanks for that. So before I attack my manifold with a file tomorrow , Does anyone know if the manifold is cast or not? I've also e-mailed the supplier to X- ENG to see if they know the max bend allowed on the TC.

Will now wait for the reply before I commit to any work then.

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My supplier says "don't bend it". However, the thermocouple is just a bead at the end of the tube so I reckon you could bend it a bit, so long as the tube neither cracks or kinks.


The functional part of the probe is the very tip. You can bend it almost

45 deg - they bend is onle a function of the stainless steel tube

bending and does not affect the temperature sensing part of the probe at


This is the response I got MadMan who sell the kits in SA. So now am unsure as to what to do. I think I'll bow to Tonk's knowledge and expierience and go for his position

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