Ok Im starting my fuel tuning with my AFC and I want to know where to put my EGT probe to help me with tuning? I keep reading from RRE that they are using 900*c for their tests where is the probe location to get those temps. Yes I know my EGT gauges is *F so i know I should be in the 12's with my gauge.

Im not concerned with how to install it I have no problem there I just want to know location. Runner#1/DP/O2 housing etc...

Mine is in my 02 housing

Jamie, read this thread I posed in it a month ago.

http://www.dsmtuners.com/forums/showthread.php?s=&threadid=104367

Some people chose the manifold, but I chose behind the turbo and if you read my and some of the other posts it will give you some great results.

That was a good bit of information, but I am suprised about something. In all of that no one mentioned that if you put the probe in the o2 housing and it breaks, no biggie. If it's pre-turbo and it breaks you are SOL, thats a big reason to not put the probe pre-turbo.

Originally posted by DSMJim
Jamie, read this thread I posed in it a month ago.

http://www.dsmtuners.com/forums/showthread.php?s=&threadid=104367

Some people chose the manifold, but I chose behind the turbo and if you read my and some of the other posts it will give you some great results.

Click to expand...

thanks to jim, i'm putting mine in my dp, and it should be easier to put in than in the manifold too.

Dustin

Good remarks...I never thought of it breaking and blowing into my turbo. I'd rather be safe than sorry...

Thanks Jim I'll be by your neck of the woods tonight sat maybe you guys will be out. I can't wait for the injectors! Im gonna get the EGT hooked up to aid the tuning.

NP

This scares me becuase I just installed mine on the manifold and I just read a post where a guys probe broke and went into the turbo. But what I was wondering what is the chance of this happening is this something where its pretty much bad luck or its a pretty good chance it will break?

Originally posted by DSMJim
Jamie, read this thread I posed in it a month ago.

http://www.dsmtuners.com/forums/showthread.php?s=&threadid=104367

Some people chose the manifold, but I chose behind the turbo and if you read my and some of the other posts it will give you some great results.

Click to expand...

That's assuming a linear temperature drop across the turbo, which is a pretty big assumption.

mines in the DP about 1.5" from the O2 housing

If you put the EGT probe somewhere downstream from the manifold, your readings will not be accurate. Alot of cooling happens to the gas from the manifold to the downpipe. For tuning purposes it really doesn't matter since the temperature variations will still be very observable. But you won't have an accurate reading of how hot your engine is running. If you ask me, I'd tap it in the manifold. Then again, if you tap only ONE of the runners in the manifold you won't neccessarily know how hot the other three cylinders are running either.

Originally posted by sonicnofadz
If you put the EGT probe somewhere downstream from the manifold, your readings will not be accurate. Alot of cooling happens to the gas from the manifold to the downpipe. For tuning purposes it really doesn't matter since the temperature variations will still be very observable. But you won't have an accurate reading of how hot your engine is running. If you ask me, I'd tap it in the manifold. Then again, if you tap only ONE of the runners in the manifold you won't neccessarily know how hot the other three cylinders are running either.

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not trying to start anything here, but did you read the post dsmjim posted? he expains the theory of putting it in the dp or o2 housing; after the turbo...but imho think of it this way, at 50mhp your speedo is probably pretty accurate right? how accurate do you think it is at 160? same with the egt, at the manifold its almost maxing out all the time, so its not that accurate, but if its not close to maxing then it may be a little more so....like i said, not trying to start anything, just seeing if you understand why some of us are saying to put it after the turbo. yes it may cool a little, but not that much. the turbine isn't made for cooling the exhaust temp, so its not going to help that much.

Dustin

Yeah I know that there isn't going to be ALOT of cool down from the manifold to the o2 housing. They are both two very large pieces of iron that will soak up alot of heat. However, YES there will be alot of cooling from the manifold to the downpipe. The down pipe is a piece of sheet metal. Its basically one gigantic heat sink. So depending on how fast your going (how much air is passing by the downpipe) the downpipe is going to cool down ALOT faster than the 02 housing or the manifold, simply because it doesn't have as much mass. Yeah I read what dsmjim posted, but I somewhat disagree. If you measure the temperature at different locations on a car, lets say the 02 sensor housing, the beginning of the dp, the middle of the dp, and your muffler, your going to get a whole lot of variations if your traveling lets say 60mph. Why is this so? Because of physics. Your exhaust is heating up the passing air which is cooling the exhaust gasses inside the pipe. I'm not trying to be belligerent here either, just trying to share some thermodynamics I've learned in college.

I know in my diesel truck we run them in the manifold because there can be as much as 400-500*F of EGT tem change from pre to post turbo. I know this first hand because I was post and moved to pre the reason being that in an engine like in my truck at 1500*F you are only there for a few seonds and she is all over. Ideally we stay around 1300*F max WOT EGT, but in the car for some reason the manifold EGT is very high it must be the location in relation to the flame in the exhaust header.
I know in our snowmobies where we put the probe in the head pipe is critical because 2" either way and you are in the hot spot in the flame or the cold spot and render the gauge useless. So its critical has anyone tried going closer to the head just out of curiosity?
I will be going in the DP because of the high manifold egt what is the point of having a maxed out gauge all the time its not going to tell you anything but that its hot.

There's about 50-100C change from #1 to dp on these cars (depending on speed, etc). I like to know the real temp I'm seeing (and use a higher range EGT (expensive) that can handle it without maxing out). Unlikely it'll break off and the turbo will get to munch on it, but if it does, hey, time for a bigger turbo

When I bought this car, the guy before me had the EGT tapped at the #1 runner but it wasn't working anymore. Turns out that the probe had melted and stopped reading. I head the probe replaced. I'm not too worried about it breaking off since it'd probably melt first instead.

I'm probably just going to upgrade to a higher quality EGT that read to 1800 or 2000.

Has anyone compiled a table that interprets EGT readings with the probe in the manifold?

ROW

Here's my 2 cents:

http://www.dsmtuners.com/forums/showthread.php?s=&threadid=116658

Originally posted by sonicnofadz
If you put the EGT probe somewhere downstream from the manifold, your readings will not be accurate. Alot of cooling happens to the gas from the manifold to the downpipe. For tuning purposes it really doesn't matter since the temperature variations will still be very observable. But you won't have an accurate reading of how hot your engine is running. If you ask me, I'd tap it in the manifold. Then again, if you tap only ONE of the runners in the manifold you won't neccessarily know how hot the other three cylinders are running either.

Click to expand...

I'm not sure what you mean when you say it will not be accurate in the downpipe. It's not accurate in the manifold either. Besides when it's in the manifold it's just reading a different number how does that help you? Do you tune your car based on some magical number somebody thought up a long time ago that says "Your EGT in Runner #1 should be 1550 and no higher" ? There is no magical number and what somebody else says or how their car runs has absolutly no bearing on how your car will run.

When you tune your fuel and timing to make the most hp for your setup, keep an eye on your EGT to make sure it's not something crazy but ignore it for the most part. Then long after your all done tuning your car, have a look at what your EGT is. Every car and setup is different so your car will be happy at a different EGT then my car. So if yours is happy at X EGT then that is where you want to be. I dones't matter if the probe is in the manifold or the tip. As long as the guage doens't move from that position and move other then expected when your driving hard. If you think putting it in the #1 runner is giving you a more or less acurate reading your not understanding the point of what an EGT gauge is for. I could take a brand new probe and put it in your car and it will give your gauge a different reading then the one you have in your car now. Some of them vary by as much as 50deg from probe to probe.

DSMJim said:

Do you tune your car based on some magical number somebody thought up a long time ago that says "Your EGT in Runner #1 should be 1550 and no higher" ? There is no magical number and what somebody else says or how their car runs has absolutly no bearing on how your car will run.

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There is a magical number - the melting point of aluminum.

the melting point of aluminum is like 1650.... i have seen welltuned pump gas cars with no knock run WELL ABOVE that...

djpast said:

the melting point of aluminum is like 1650.... i have seen welltuned pump gas cars with no knock run WELL ABOVE that...

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He is kidding. We all know that is the combustion chamber temp (well egt probe temp is colder than combustion chamber temp) not the temperature of the piston. The heat from combustion is not really absorbed into the piston all that much really.

DSMJim said:

He is kidding. We all know that is the combustion chamber temp (well egt probe temp is colder than combustion chamber temp) not the temperature of the piston. The heat from combustion is not really absorbed into the piston all that much really.

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So it seems that it's a good idea to put EGT probe in O2 housing. But Jim, I didn't really got how you came to the difference between readings in manifold and O2 housing be exactly 200F. Miata has a different exhaust system and making such a parallel is imho improper.

Thanks to your and Tsunari posts I want to put my Autometer EGT probe into O2 housing, but how do I know what should be the maximum readings in there before the melting of engine components starts?

Mines going in the DP.

Stazik said:

So it seems that it's a good idea to put EGT probe in O2 housing. But Jim, I didn't really got how you came to the difference between readings in manifold and O2 housing be exactly 200F. Miata has a different exhaust system and making such a parallel is imho improper.

Thanks to your and Tsunari posts I want to put my Autometer EGT probe into O2 housing, but how do I know what should be the maximum readings in there before the melting of engine components starts?

Click to expand...

This is what I'm trying to get people to understand.

You don't watch the EGT guage when your tuning your car and hope to see a particular number. Take your car to the dyno and setup your air fuel and watch your timing until you have the car at an air fuel and timing level that makes the power you want. Or do it on the street with a logger like we have been doing for years. Or go to the track and set it up until you have the air fuel in the 11.5-12.0 range which we all know to be perfectly acceptable for a turbo car, whatever you want. Now after your car is set and you just ran a fast 1/4 mile time (so you know your car is all set) start to pay attention to your EGT more and see what the numbers are reading. Whatever EGT you are now seeing is what your car is happy with and where the guage should read with the air fuel and timing setup properly. EGT is a product of Air/Fuel and Timing. If those are set properly then your EGT will be inline as well.

Once your car is tuned you can now see, ok XXXX is where my car is happy so if it get hotter then that then I know something is up. I does not matter if the guage points towards a piece of cake, as long as it doesn't go higher and point towards a double layered cake then all is good. What the number happens to be is not important, obviously unless it's something crazy. Lets use common sense when taking this into account, right? If you move the probe even one inch it will change the readings on the gauge drastically. This is why you can not just take a particular number that somebody is throwing around as the gospel. This is also why it doesn't matter where the probe is. Once your car is setup and you see that EGT on yoru car with your probe where ever you put it is XXXX number then that is where YOUR car is happy.

I highly recommend people do not use EGT to tune with, however that is just my method. I have found that EGT gauges are wildly different when you go from car to car (even with the probe in the same location, manifold or O2 whatever) Even if you change your probe but keep your gauge you get a totally different reading with it installed in the same spot. It's for this reason that you don't worry what the number is particurarly just that it's reading the same thing all the time and doesn't change (at WOT obviously, part throttle it will change depending on how much your pushing the gas)

Lets set the record straight, I dont think putting it in the manifold is a bad idea, it is fine as well however I chose my downpipe personally. For my method of tuning it does not matter where the EGT is. It could be in the muffler for all I care. I'll just know that the gauge is going to read really low then. Well thats a bit far, but you get the idea. I can easily weld up a hole in my SS downpipe (which I made by the way) and not worry about it rather than trying to plug a hole in my $400 cast Turbonetics manifold.