EGT probe where to put it and why?

[Stazik]

Excellent post! You are right. If you want to know what's your engine temperature is - put probe in the manifold, otherwise put it elsewhere, note the point when car runs fine and be warned by anything above that.

But let me make that clear, why everyone is talking about 1600-1650 F? Is it a reliable maximum temperature for stock 4g63 if measured in the manifold 2" away from the block?

Another thing that confuses me in regard to probe placement is that every exhaust part consumes heat unequally throughout the time, for example if you're riding 60mph at 5k rpm your EGT will be different than driving 120mph at 5k rpm, because of incoming air cooling down the system obviously.

So my conclusion is, that in case you’re not afraid parting melted probe by turbine propeller maybe it’ll still make sense to place the probe as close to the block as possible, so readings are more accurate. Therefore when readings change, their change will be more accurate when less heat-consuming parts are between probe and the block.

 

[hellotbone]

Jim makes perfect sense on his reasoning and can tune the hell out of a car he tuned mine last night. Well said Jim.

 

[tsunari]

Ok think of it this way . . . In all the cars I have driven, the oil pressure, engine temp, etc . . . gauges have been different. Some read a little high, while others read a little low. What I do with my cars is once I make sure nothing is wrong (car isn't over heating, oil pressure is INFACT adequate, etc. . .), I make a mental note of what the gauges are reading and tell myself- ok . . . this is NORMAL. If the oil pressure drops much below this while cruising, etc. . . I've got a problem. OR if the coolant temp gets much above this, I'd better stop.

Pretty much the same thing that Jim is suggesting.

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?

 

[DSMJim]

Ok think of it this way . . . In all the cars I have driven, the oil pressure, engine temp, etc . . . gauges have been different. Some read a little high, while others read a little low. What I do with my cars is once I make sure nothing is wrong (car isn't over heating, oil pressure is INFACT adequate, etc. . .), I make a mental note of what the gauges are reading and tell myself- ok . . . this is NORMAL. If the oil pressure drops much below this while cruising, etc. . . I've got a problem. OR if the coolant temp gets much above this, I'd better stop.

Pretty much the same thing that Jim is suggesting.

Praise Jesus! Somebody understands what the hell i'm talking about...

Hellotbone : With another 30 mins we could have done a whole lot more, was lucky I coudl slip out then without any problems.. ...

 

[Cirus_93TSI]

if your egt probe isnt in a runner on your manifold, then its in the wrong place and its not giving you a correct reading. your egt is supposed to measure the temp of the exhaust gas BEFORE the turbo, if its after the turbo you have no idea how hot your manifold and turbo are, which is what your trying monitor and keep from getting too hot by buying an egt. how hot the air inside your downpipe is doesnt mean crap, by that point the exhaist air has already passed through the turbo, and the turbine wheel, and 5 feet of metal, and has transfered alot of its heat to that metal.

the point of an egt guage is to see how hot the air going into your turbo is, to keep from damaging the turbo or the exhsut manifold. if you put your egt probe after the turbo, then your egt guage is nothing but cosmetic, and serves no real purpose.

you can all think what you want, and stick your egt probe 3 inches before your mufler if you want to, it will still give you a reading so you can have another pointless guage for looks alone. but the probe should be before the turbo in the manifold runner if you want to actually see how hot your exhaust gas is and be able to use that reading to tune your car. try and tune at high boost using an egt reading from your downpipe, and you can just wait for your engine to go up in smoke, since what you think the temps are, is really alot less then then actual temps.
all egt temps and tuning advice relating to egt temps are refering to the correct reading from the exhaust manifold, so if you dont put it there, you can just forget all those numbers, cause they mean nothing unless your probe is getting the right reading.

 

[Cirus_93TSI]

oh, and on a side note, i do know people that run dual EGTs on their dsm's. 1 in the manifold, and 1 either before the cat/test pipe, or inbetween the cat/test pipe and the muffler. but i have never known anyone that didnt oput on in the manifold, cause that temp reading is the important one.

 

[tanner261]

oh, and on a side note, i do know people that run dual EGTs on their dsm's. 1 in the manifold, and 1 either before the cat/test pipe, or inbetween the cat/test pipe and the muffler. but i have never known anyone that didnt oput on in the manifold, cause that temp reading is the important one.

What he said

I have no idea why you would want to put an EGT after the turbo, by then it is too late. There is a lot of energy/heat transfer to spin the turbine wheel, and the air has decelerated after making so many bends to get to the downpipe. Idealy you want a probe in each manifold runner, but this can get expensive.

I had a Greddy gauge and probe, the probe eventually failed and went through the turbo but did not cause any damage. I replaced it with an Omega probe with an Inconel tip, part #TC-K-NPT-G-72 Project #EI1202104. It is the most duable/fastest reading probe available from Omega. The Inconel is good past 2000*F, and the probe costs around $60.

 

[DSMJim]

<shakes head>

Ok, whatever. Put your probe where ever the hell you want. I seriously don't know why I even bother some times. :thumbdown

 

[Nub Styles]

Well DSMJim, you really changed my whole idea of what the EGT is used for. I thought there was XXXX temp you were not supposed to exceed and the egt gauge told you whether or not you were within limits of that temperature. But what you're saying is to let the gauge establish a medium with your car's current set-up? And then just keep an eye on it incase temps go way above the pre-established medium? Interesting... In light of this, it seems irrelevant where the EGT goes. I agree after the turbo seems much safer, incase the probe would break for whatever reason. After reading this thread, I've got a pretty good idea of where I'm going to put mine when I get it. Thanks.

 

[bigroy_80]

exactly jim dont let people get you down because they want to say what they think is the right way, and basically brush off your theory. which to me your idea sounds so much like it would be common sense that people would think of it themselves. before readin this i had always thought there was a best place and predetermined temp but you brought out the common sense that just shows that like you said all cars are different meanin there CANT be a predetermined temp. a high temp for one car might be low for another and vice versa. tahnks for sheding light on the people willin to learn such as me.

 

[tanner261]

Have you ever seen a turbo engine being calibrated for the OEM? Ever wonder where they put the probes? One in each manifold runner; before, in, and after each catalitic converter. You will not see that immediate temperature spike in one cylinder if the probe is in the downpipe.

Everyone who says that the EGT is used only as a safety is exactly right. There is no temperature that you should tune for, just keep it under 900*C. The probe will not break/melt if it is high quality.

Put your EGT wherever you want, just know that the results may not mean anything depending on the location.