Best EGT location

[david-b]

Hey all;
Just bought an EGT gauge for the car and was wondering where the best location for the probe actually is. I've heard far, like by the tip of the exhaust or so. True? Thanks.

[TalonEclipseMixGsx]

My aftermarket exhaust manifold came pretapped for a egt gauge. I would think that would be the most accurate reading. I actually bought a gauge, as well, a few months back, just been too lazy to install it.

[SilvrEclipse]

David, heres what I ended up doing. Your suppose to drill a hole in your #4 exhaust runner about 1-2" off the head. Instead of threading the hole and screwing that nut in, I just had it welded to the manifold. It worked very well.

I can get pics if you need them.

[david-b]

That's what I'm trying not to do is weld anything.

Another problem, I've got an aftermarket header which seems kinda thin in my book. I'm wondering now if I can even thread something into it. Which means I may have to get it welded then. I'll have to check out the probe once it comes in.

[SilvrEclipse]

I installed my gauge about 3 months prior to turbo. I had it welded in my header to make sure everything worked. If you dont have access to one Im sure you could take it somewhere and have it done real cheap.

[NateS]

I actually bought a Stewart Warner EGT gauge/sensor. In their directions they recomend for a turboed car to have the egt gauge mounted somewhere on the downpipe. For a N/A car they suggest to have it mounted right into the exhaust manifold. However, mine will be mounted into the exhaust manifold anyway.

[SilvrEclipse]

You actually dont want it on the downpipe. That gives the temps time to cool down so you wont know exactly how hot it is coming out your cylinders. I have heard that if you tap it into your DP add 200 degrees to the temps and thats whats you would get if you had it in the manifold.

[david-b]

It's crazy the difference a couple inches makes. I had a link which I lost that says exactly how far from the head to put it. But I'm at work and I lost it. It should be in runner 4, right?

[SilvrEclipse]

yea the 4th runner. Mine is about 1.5" fron the head I think.

[Thor06]

Thats where my ported 2g mani and my FP mani are drilled. You should be able to just run a tap or self tapping screw through it, it wont make the best of threads, but it should be enough. Personally though, I would just weld the bitch if the manifold isnt cast.

[kjewer1]

Hopefully by "4th runner" people mean 4th runner from the left. You want it in the cylinders that run leanest, which are 1 and 2 (on the right). Putting the EGT probe after the turbo definitely makes it even more worthless than it would normally be right after the head, if you intend to make tuning decisions based on it's measurement. The only compelling reason to put the probe after the turbo is that when the probe eventually fails (and they will) the pieces won't go through the turbo. And I'm sure any manufacturer recomending you do it this way does so for liability reasons. I've had probes go through the turbo and not damage them, probably because it's pretty well melted at that point and relatively soft.

For a tubular manifold, you definitely want to weld a bung on! For a cast manifold, drill and tap. Most probes or their holders are 1/8th NPT. Drill and tap with the motor running, the exhaust manifold pressure will blow most of the chips out the hole. ~2" from the head on runner 1 or 2 will work.

In the end EGT gauges aren't worth all that much on turbo motors. To make an extremely long story short, they are a much better indicator of what you're ignition timing is than what your AFR is. And we can just log timing these days. A wideband costs 2-3 times what a typical EGT gauge does, but it's infinitely more useful. If you choose to run an EGT gauge there is nothing wrong with that, they can provide some interesting data (try playing with turbine housing and wheel size) and alert you to a big problem, just be careful about using them for tuning based on some arbitrary absolute value.

[2of9]

pics would be awesome btw

[david-b]

Originally Posted by kjewer1

Hopefully by "4th runner" people mean 4th runner from the left. You want it in the cylinders that run leanest, which are 1 and 2 (on the right). Putting the EGT probe after the turbo definitely makes it even more worthless than it would normally be right after the head, if you intend to make tuning decisions based on it's measurement. The only compelling reason to put the probe after the turbo is that when the probe eventually fails (and they will) the pieces won't go through the turbo. And I'm sure any manufacturer recommending you do it this way does so for liability reasons. I've had probes go through the turbo and not damage them, probably because it's pretty well melted at that point and relatively soft.

For a tubular manifold, you definitely want to weld a bung on! For a cast manifold, drill and tap. Most probes or their holders are 1/8th NPT. Drill and tap with the motor running, the exhaust manifold pressure will blow most of the chips out the hole. ~2" from the head on runner 1 or 2 will work.

In the end EGT gauges aren't worth all that much on turbo motors. To make an extremely long story short, they are a much better indicator of what you're ignition timing is than what your AFR is. And we can just log timing these days. A wideband costs 2-3 times what a typical EGT gauge does, but it's infinitely more useful. If you choose to run an EGT gauge there is nothing wrong with that, they can provide some interesting data (try playing with turbine housing and wheel size) and alert you to a big problem, just be careful about using them for tuning based on some arbitrary absolute value.

Great info. Now how about for us few N/A people?

[kjewer1]

I never ran an EGT probe on a NA car, so I can't offer any first hand advice there. But I'm still inclined to believe that the EGT isn't very useful, especially considering how cheap and readily available WBO2s have become, which are far more useful.

[SilvrEclipse]

It still not a bad idea to have one though.