EGT Thermocouple Size

[RaggedyMan]

I have searched but not finding what I want.
Can someone tell me what is the correct size for the thermocouple? I just received my gauge, etc from Hewitt and they sent a straight "K", 1/4" 2-3" exha. Perhaps I'm over thinking this and it's why I can't readily find the answer but for one it seems a 1/8" would be easier(?), safer(?) (I'm thinking the smaller I have to drill and tap, the better) and I have no idea what the length of the probe should be and will the straight work or should it be 90*?

 

[rustystud]

When you ordered you EGT gauge you should have specified what thermocouple you wanted. So they sent a 1/4" one ? That should work just fine.

 

[RaggedyMan]

When you ordered you EGT gauge you should have specified what thermocouple you wanted. So they sent a 1/4" one ? That should work just fine.

Therein lies the problem, I had no idea there were options. Reading through a few of the hundreds of posts about installing egt gauges I never got to one that would lead me to believe there was a preference or choice. I assumed (yes, I know) that it was a matter of "buy gauge, install".

Thank you for your response O-Rusty one.

 

[Welder1]

When you order a thermo couple there are several options as to what size fitting, length of probe and cable straight or 90*. The one I used I believe was a 1/8" NPT with a 90* end. That allowed an easier fit to route the cable.

 

[74M35A2]

TC's are part of my daily job. The thinner the TC, the faster its response rate will be, but lower its durability is. Go thinner if you are trying to run the edge of piston melt and knowing when to back down, and then change it maybe every 1-2 years. Or, go thicker for just general info, and not have to worry about it. If you are running the EGT probe post-turbo, then nobody cares if it breaks off and flies out the pipe. If pre-turbo, like most recommend, then could go small dia for fast response, but don't bury it deep in the pipe. That way it will be more durable and if it does break off from vibration, it will be a short piece and can pass right through the turbine wheel with little to no damage. The sensing element (junction) is in the very tip.

No scares on drilling a cast iron manifold either. It produces powder not shavings. Those will blow right through the turbo at first start, even before the turbo begins to spin. No need to use a vacuum, grease on the drill tip, remove turbo, all that.