Different EGTs with different probe locations (1 Viewer)

[Adam B]

Background:

When I originally installed my pyrometer probe 3 years ago I wanted to do it without removing the exhaust manifold and turbo but I also didn't like the idea of drilling and tapping directly above the turbo and losing an unknown amount of chips into the turbine. So...I chose a location where the chips would fall straight down and I could retrieve them with a magnet. It worked very well but that location ended up being the nice thick part between cylinders #4 and #5. I had never seen a 2 piece exhaust manifold before and had no idea that I was drilling right through the joint. Bad spot.

So after a couple of years of leaking exhaust I finally had the chance to relocate my probe to the ideal spot this past weekend when I was swapping turbos. I drilled and tapped in the front of the manifold directly above the turbo where the flow of exhaust from 1,2,3 meet up with 4,5,6. Good spot.
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Results:

What I find very interesting is how my EGT gauge responds with the probe in the new location.

The temperature goes up MUCH faster now that I'm getting flow from all 6 cylinders.

The temperature also drops noticably faster and seems to settle to the 350F range quicker than before.

I haven't had a chance to do any sustained runs with a heavy load because it's all been city driving for the past few days but tomorrow I'll head out for the weekend and run my test hills with my usual heavy foot so I'll find out if the actual max EGTs read any different or if it's just a faster response.

Does anyone else have similar / different results from different locations?

 

[Radd Cruisers]

My 12Ht has the probe pre-turbo and the gauge responds very quickly to throttle changes.

~John

 

[Tapage]

I never try another location ..

But my pyro can go faster than my rpms .

 

[ForealBoreal]

I did the exact same location as tapage.
I was a bit shocked how the temps got hot quick when climbing big hills.
But I purposly drove like a granny on hills before the install.
I did a granny test and a normal test and I was ok for the hills I encounter.
I think the 3 inch exhaust keeps things really cool. I am really happy now
Victoria bound in the am!

 

[Adam B]

That's where mine is now.

 

[ForealBoreal]

how did you end up plugging the hole?

 

[Adam B]

I just ran the tap deeper than I originally had, so that the 1/4NPT plug I used would actually be threading into the inner part of that stupid exhaust manifold joint, if that makes sense. The short part of the ex manifold goes inside the long part and the plug is going through the outside part into the inner part. It seems to be at least somewhat sealed...whatever that means. Obviously that means my manifold isn't going to be able to expand "normally" at that stupid joint but if it can't expand between any other cylinders why worry about it expanding between #4 and #5?

Did I mention that the exhaust manifold joint is stupid?