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What's The Most Effective Location For An Exhaust Temp Sensor

666DAN

By 666DAN,
in Engines & Forced Induction

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666DAN Grand Master

666DAN

Posted
Posted

I've got an exhaust temp gauge to fit and just wanted some opinions on the best location for the sensor, I've currently got a CES stainless split dump with HPC coating...so really didn't want to touch that., but then again I want the temperature sensor to actually be doing a proper job.

Guilt-Toy Grand Master

Guilt-Toy

Posted
Posted

ive sen holes drilled in the rear housings of turbo's that ive imported from japan second hand. they seem to be putting them into the rear housing of the turbo's...

Angus Smart Grand Master

Angus Smart

Posted
Posted

now i would like to add to this question as i've recently fitted one to mine. and put it down in the merging part of the front pipe.

what tempature ranges are good?

they tell you if your running lean/righ etc right?

mattymagoo22 Community Regular

mattymagoo22

Posted
Posted

hi guys i'm still trying to figure the best spot as well, but i really think that your reason for having the exhaust temp sensor is the determining factor i.e is it there just to keep an eye on things, are you checking individual cylinder temps (sensor in every exhaust outlet in your manifold) are you looking to run leaner than 14.7:1 and want to keep your exhaust valves intact?

my turbo had a 1/8 bsp fitting (from memory) just after the flanges from manifold to turbo and I think thats a pretty good spot as your can get an average idea of what you cylinder temps are and the heat that your turbo is copping?

My thoughts on the matter,

cheers Matt.

Dale FZ1 Veteran

Dale FZ1

Posted
Posted (edited)

Exhaust temps are an INDICATOR of rich/lean - if you want to know HOW rich/lean then invest in a wide band O2 kit.

Pyrometer will measure (obviously) temps which are thermally loading the pistons, valves, manifold and turbocharger. All of them have thermal limits.

There are good reasons for inserting the thermocouple into the manifold pre-turbo, but generally it is too difficult/not practical to muck around welding into cast manifolds or a fabricated manifold collector. A disintegrating sensor getting blasted into a turbine would not end happily...

A turbocharger WILL see a temperature reduction across the turbine (energy transferred to the turbine to drive the compressor), so basically if you want any meaningful indicator of thermal loading then mount it as close as practical to your turbine discharge. ie. in the dump pipe.

FWIW, I'm seeing 500-650 with general running about. Closed loop operation about 700, and with extended higher rpm, aggressive throttle openings and boost up to 750.

Edited by Dale FZ1
Angus Smart Grand Master

Angus Smart

Posted
Posted

oh so where i have it is rather pointless. and i know my afr's are well below 10.

not to worry really. fuel pressure i have also which i didnt think i would really need also.

Beer Baron Grand Master

Beer Baron

Posted
Posted
well the standard one is at the cat.. i would like to have it at the cat. before it so i can measure the temps and back off before it runs the cat into melting mode..

the standard one doesn't give you any temp readings though. it's just there to tell you two things. 1. your cat is overheating and 2. dont park on long grass.

it's a waste of time to buy a proper exhaust temp gauge and mount it there. you may as well check your EGTs with the back of your hand...

mattymagoo22 Community Regular

mattymagoo22

Posted
Posted (edited)

yeah the one in the cat is after the matrix and its called an after cat temp sensor as explained above to let you know theres a problem. temps at exhaust manifold upwards of 750oC at the cat around 300oC. EPA can measure temps before and after cat matrix to tell if its still intact.

I really think the best spot is before the turbo. That doesn't mean that you have to weld anything, drill a hole in the turbine housing tap a thread into it, its cast there won't be a problem, just use grease to catch the swarf ( some thread repair guys have tiny vacuums....)

Matt

Edited by mattymagoo22
Dale FZ1 Veteran

Dale FZ1

Posted
Posted

True from a technical perspective. As I said earlier, there is a temp differential across the turbine due to energy transfer into the rotor.

From a practical perspective, I'm happy with installing in the dump within a short distance of the turbine outlet. I may not have the best absolute reading, but it's not a bad indicator.

Unless I had the turbo off, and turbine housing removed or manifold off I'd not be interested in the possibility of sending metal shavings through the turbo.

This discussion is similar to "where is the best place to measure engine oil temps?" ; there are options, some better than others.

WilYawn Enthusiast

WilYawn

Posted
Posted (edited)

I have a GT2510 and it has a small bolt thingy just after the flanges from manifold to turbo. Anyone know what size it is? Would it be a good spot for a EGT sensor?

post-31094-1171077611.jpg

Edited by WilYawn
mattymagoo22 Community Regular

mattymagoo22

Posted
Posted

yeah thats the spot i was talking about and I'm pretty sure its 1/8th BSP pipe thread, there are pyro sensors that will screw in no probs. (don't ask me which but I've seen em and the turbo I bought had one in it but was not sold with the turbo)

the closer to the exhaust valve the better. combustion temps 750oC and up, tail pipe 100oC maybe , the heats got to go somewhere, just my opinion.

It is in no way difficult to tap a thread in the spot pointed out on the above photo( it may already be there just has a plug in it), or in the collector of your standard cast manifold, and when done properly the risk of metal filings 'damaging' the turbine is far from high, however I wouldn't recommend it for the mechanically inept as your concerns may well be realised if done incorrectly.

cheers Matt.

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