# EGT Probe placement



## aminidab (Apr 30, 2002)

I'm installing an EGT probe in the hopes of preventing any more piston melting in the future. I was wondering what everyone thinks is the best place to put the probe. From reading info here and on sr20forum, there are 3 different places I've sent people put the probe.

In the cylinder #1 runner about an inch from the head
In the collector just before the turbo flange
Right after the turbo

Obviously the readings would be much lower if it were installed after the turbo, and it would take longer for the readings to change. Which would mean it could be possible to not notice a problem before it's too late.

For the other 2, the tradeoffs I see are cylinder #1 is the leanest and putting it there would be closer and more accurate. But that would only give a reading for that cylinder and wouldn't indicate a problem with a different one.

I'm leaning towords putting in the collector right before the turbo flange, what do you guys think?
Oh and I don't really know much about welding, would it be fine if I just got a muffler shop to weld the fitting in?


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## Chuck (Nov 19, 2003)

definatly put it in the collector.. it will get readings from all cylandars.. so it will be a generalized over span of heat.. only thing i worry about.. if the EGT sensor melts, or something breaks off, its next destination is your turbo...


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## dave_f (Dec 11, 2002)

I put mine in the collector right beofre the turbo. I think that would be the best spot for it.
-dave


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## aminidab (Apr 30, 2002)

Ok Looks like I'll probably put it in the collector then. I'm also planning on getting a 1/8 NPT plug so I don't have to have the probe in all the time.


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## aminidab (Apr 30, 2002)

I got my the EGT bung weled into my manifold today. Here are a couple of pics. They were taken with a cell phone, so they look kinda crappy.

EGT Fitting 
EGT Fitting Closeup


If you can't tell from the pics, I got it welded into the #1 runner, about 1/2 inch from the turbo flange.

Another thought I had, the NPT plug I was going to use when I didn't have the probe installed is made of brass. Doing some basic searching around the net I found that the melting point of brass is around 1680 to 1800F. Do you think that's too close to the max temps I would see(figuring 1600F max)?


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## se-r-57 (May 1, 2002)

Just get a steel or a stainless plug. Put some antiseize on it.


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## javierb14 (Jul 9, 2002)

i usually place my EGT probe in the runner about 1.0 in. away from the head flange. though if i were concerned about preventing a future failure, i would invest in guage that has some sort of peak/hold function that displays injector duty cycle and or MAF voltage......the techtom comes to mine 

http://www.technosquareinc.com/cmx.htm

there are also a few wideband controllers/displays available that have some cool features. such as datalogging your AF ratio vs RPM. you can use a PDA to datalog too, you dont have to carry a lap top everywhee


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## aminidab (Apr 30, 2002)

javierb14 said:


> i usually place my EGT probe in the runner about 1.0 in. away from the head flange. though if i were concerned about preventing a future failure, i would invest in guage that has some sort of peak/hold function that displays injector duty cycle and or MAF voltage......the techtom comes to mine
> 
> http://www.technosquareinc.com/cmx.htm
> 
> there are also a few wideband controllers/displays available that have some cool features. such as datalogging your AF ratio vs RPM. you can use a PDA to datalog too, you dont have to carry a lap top everywhee


Cmon if I didn't have my laptop, I wouldn't feel like brian o'conner :loser: 
Seriously though I'd love to have something like that but I'm sure it would cost plenty of $$$. Realisticly I'd probably be more interested in something like this: http://www.sr20forum.com/showthread.php?t=68821


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## wes (Apr 30, 2002)

I mountedmine so that the probe protrudes in to the collector. It points downward and pretty much places the tip close to the center of the collector. I also chose this so that the probe was not visible when installed as the wiring and probe are on the back side of the manifold. 










Where will your be pointing in that position? I just looked at my manifold and it looks as though your's will point up in the runner? Have you put the probe in place to check that? Regardless it should give you a good reading.


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## aminidab (Apr 30, 2002)

The probe points directly towords the center. The tip ends up being maybe 1/2 inch away from the center of the collector.
I'll try and take some better pictures today or tommorrow.

From looking at it I thinking the reading should be affected by the other cylindars.


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## wes (Apr 30, 2002)

aminidab said:


> The probe points directly towords the center. The tip ends up being maybe 1/2 inch away from the center of the collector.
> I'll try and take some better pictures today or tommorrow.
> 
> From looking at it I thinking the reading should be affected by the other cylindars.


Cool that's the way you want it. Although after taking my head off today cylinder 3 is also where my gasket was blown. The only thin gis it was a very minor leak. gasket ring was fine but you could tell it wasn;t sealed properly allowing coolant to leak in around it. Motor looks great and the coolant cleaned #3 nicely. I am thinking 3 runs the hottest hence your issue as well. Perhaps the EGT very close to the head on #3 would allow us to monitor the hot spot per se. I will rpobably have a bung welded in place so I can experiment with placement.

Also Nissan changed the head gasket for the GA16. MUCH nicer than the original design. Different material all together.


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## Chuck (Nov 19, 2003)

what.. a nissan oem replacement gasket is different than the stock one?


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## wes (Apr 30, 2002)

Chuck said:


> what.. a nissan oem replacement gasket is different than the stock one?



No. Nissan re-designed the head gasket. The new one is a different material than the old one.


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## aminidab (Apr 30, 2002)

wes said:


> Cool that's the way you want it. Although after taking my head off today cylinder 3 is also where my gasket was blown. The only thin gis it was a very minor leak. gasket ring was fine but you could tell it wasn;t sealed properly allowing coolant to leak in around it. Motor looks great and the coolant cleaned #3 nicely. I am thinking 3 runs the hottest hence your issue as well. Perhaps the EGT very close to the head on #3 would allow us to monitor the hot spot per se. I will rpobably have a bung welded in place so I can experiment with placement.


Huh so maybe it was a good thing I put in at the end of the #3 runner. It's not a complete coincidence though, that was part (a very small part) of the reason I put in there.



> Also Nissan changed the head gasket for the GA16. MUCH nicer than the original design. Different material all together.


Hmm well in the end I did also have to replace the head gasket on the new engine(don't ask), but I used one from an autoparts store, so who knows which design it is. Ordinarily I would have used the Nissan one, but thats how it worked out.


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## Chuck (Nov 19, 2003)

hmm. i may consider getting the nissan OEM new gasket.. considering as i am going to be replacing my head.. btw, i seen adminidab's HS manifold and disco potato.... and let me say, that is one pissed off combination.. jesus.. also, i got to see all the little nick nacks.. and a completly torn apart engine.. its a very interesting site.. 

but i seen how he got the temp sending unit welded in... damn good quality weld..

Lol.. he said "that thing was a pricey manifold, so i was nervous having someone weld into it".. you know.. hotshot ought to include that already pre-welded in..


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## wes (Apr 30, 2002)

Chuck said:


> hmm. i may consider getting the nissan OEM new gasket.. considering as i am going to be replacing my head.. btw, i seen adminidab's HS manifold and disco potato.... and let me say, that is one pissed off combination.. jesus.. also, i got to see all the little nick nacks.. and a completly torn apart engine.. its a very interesting site..
> 
> but i seen how he got the temp sending unit welded in... damn good quality weld..
> 
> Lol.. he said "that thing was a pricey manifold, so i was nervous having someone weld into it".. you know.. hotshot ought to include that already pre-welded in..


Hard to include it pre welded as there are different size bungs for different probes. Depends on the gauge company and probe used. 

I am hoping the re-design of the gasket makes it better, time will tell. I wouldn't feel comfortable using a non OEM gasket though. Did your have metal inserts arounf the oil jacket passages and combustion chamber openings? My gasket appeared to not seal well around cylinder 3 on the front and back of the motor. All of the other chambers had carbon around the entire metal insert which is normal and you could see evidence of coolant passing the metal ring. I am goind to check the head and block carefully around that area to make sure it is within spec.


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## Chuck (Nov 19, 2003)

im not sure yet wes, im waiting for my head to be polished.. once i get it taken off.. ill look at the gasket, hell, ill take pictures... we can see from there..

you know i wonder if maybe your head wasnt tightend in the correct order.. you said you didnt have good seal around #3.. well.. hmmm


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## javierb14 (Jul 9, 2002)

OEM nissan parts :thumbup:


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## Chuck (Nov 19, 2003)

well see if it holds together my turbo ga... Go nissan!!


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## wes (Apr 30, 2002)

Chuck said:


> you know i wonder if maybe your head wasnt tightend in the correct order.. you said you didnt have good seal around #3.. well.. hmmm


Impossible as I did the install  And because it held for over 3000 miles after the cylinder head install. 

I can tell you I will be using an angle wrench this time instead of a torque wrench.


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## Chuck (Nov 19, 2003)

Lol


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## aminidab (Apr 30, 2002)

wes said:


> I am hoping the re-design of the gasket makes it better, time will tell. I wouldn't feel comfortable using a non OEM gasket though. Did your have metal inserts arounf the oil jacket passages and combustion chamber openings? My gasket appeared to not seal well around cylinder 3 on the front and back of the motor. All of the other chambers had carbon around the entire metal insert which is normal and you could see evidence of coolant passing the metal ring. I am goind to check the head and block carefully around that area to make sure it is within spec.


I know the head gasket I bought has metal inserts around the combustion chamber openings, I don't remember if there are any around the oil passeges though. Head gasket appears to be working well at this point, I've driven the car around 200 miles without any problems so far. Also there dosen't seem to be any oil in the coolant or coolant getting into the exhaust ports. Time will tell how well it holds up to boost though. I would have preferred to get an OEM gasket, but this is the way it turned out.


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## javierb14 (Jul 9, 2002)

aminidab said:


> http://www.sr20forum.com/showthread.php?t=68821


interesting.....im going to have some of my EE buddies take a look at this stuff.

oh ya, here's my EGT


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## NotAnotherHonda (Aug 7, 2003)

when im lonely, i get hard-ons looking at your welds javier...


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## javierb14 (Jul 9, 2002)

haha.....i dunno what to say.


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## aminidab (Apr 30, 2002)

So I finally got my turbo setup re-installed and I have a couple of questions about EGTs. I've read that a max of around 1400-1450 is ok and I know that 1600F is too high, but what is the point where it's not safe to go beyond?

In doing some testing I saw the EGTs get up to 1460-1480 on a long gear pull, and I let off. Is this too high?
If I kept going I don't think the temp would have gotten much higher, maybe 1500 but this is still higher than I would like to go. Any suggestions on what would cause the temps to get this high? I know it could be running lean, one thing I want to check is what the MAF voltage is at these temps. Is there anything else I should check?


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## dave_f (Dec 11, 2002)

what are you running for timing?





aminidab said:


> If I kept going I don't think the temp would have gotten much higher, maybe 1500 but this is still higher than I would like to go. Any suggestions on what would cause the temps to get this high? I know it could be running lean, one thing I want to check is what the MAF voltage is at these temps. Is there anything else I should check?


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## aminidab (Apr 30, 2002)

The timing is set at 10 degrees.


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