lets all figure out how to make a fast EGT probe

[acannell]

okay so when I floor it and its at WOT climbing through 4th i REALLY doubt that exhaust temperatures are taking 10 seconds to reach their final value, but thats what my autometer egt gauge says.

i would think the exhaust gas stream would instantly reach its new temperature based on the air fuel ratio, just like when you adjust an acetylene torch mixture it instantly changes temperature.

the problem is the EGT probe is 3/16" diameter and is passed into the exhaust manifold runner via a brass fitting, which it fits into very snugly. this means that the probe is ALSO measuring the exhaust manifold temperature, which i am sure changes much more slowly than the actual exhaust GAS temperature, and is what is probably slowing down the response of the probe, along with the probes relatively LARGE mass

what is needed is a MUCH smaller probe, which is passed into the exhaust manifold with some kind of insulating material like a ceramic or asbestos to greatly increase the thermal resistance between the probe and exhaust manifold.

any ideas?

i think some kind of asbestos tube for the probe to pass through "captured" inside a brass fitting with a through-hole screw on lid might work, along with a 1/8" or smaller probe

[acannell]

insulator tubes:

Thermocouples: Protection Tubes and Insulators

[ATaylorRacing]

It is more than likely the gauge, not the probe...about all the probes are alike, but the gauges can read temp as little as once or twice per second while others can read 100 times per second.

[jim34]

Somethings not working right if it takes ten seconds to respond. could be placement, bad engine tune, bad gauge or thermocouple.
I had a bad westec gauge that was slow and didn't read correctly.

[puppet]

GENUINE MITSUBISHI TRANSMISSION PARTS

[acannell]

Nicccceeeeeee Drooooooollll Orderrrinnnggg Noowwwwww

[acannell]

all probes are absolutely NOT alike. a bare tip probe with an exposed junction will have a sub-second response time (like the one puppet posted) while a 3/16" probe like I am using will have a multi-second response time. check out mcmaster.com in the thermocouple section for a list of probes and their associated response times.

plus, like i said, the fact that the probe that came with my autometer gauge is in direct contact (and for about 1/2" of its length) with the METAL exhaust manifold which has a MUCH lower thermal resistance than the exhaust GASES, what I have is an EMT probe...exhaust MANIFOLD temperature probe

for instance: I get my egts up to 1500F then let off the gas and put it in neutral...the gauge still reads 1500F and takes about 5 seconds to get down to 1300F...im ABSOLUTELY sure my exhaust gas temperatures arent anywhere NEAR that IMMEDIATELY after i take my foot off the gas

[acannell]

i cant wait to get that probe i hope they have it in stock. its EXACTLY what i want

[jim34]

Well like I said before if it takes a long time to respond then theres something wrong because ive seen more than one egt gauge and they dont take more than a second to do anything, that is the same probe that comes with the zeitronix afr meter and you will need a digtal gauge to take advantage of it.

Why would your gauge keep climbing after youve let off the gas ? mine drops immediately makes no sense and changing probes is just waisting money

[xrattiracer]

you could certainly run an exposed junction probe, but it would last about an hour. thats the tradeoff you have to make, response time vs longevity.

[puppet]

Those probes come with a year warranty and I know guys running them longer than that.
They're good.

[speeduphoria]

Quote:

Originally Posted by puppet GENUINE MITSUBISHI TRANSMISSION PARTS

Hey those guys are in my backyard pretty much. I forgot about them, thanks for refreshing my memory, lol. I've read good things about TRE

[ATaylorRacing]

Quote:

Originally Posted by acannell all probes are absolutely NOT alike. a bare tip probe with an exposed junction will have a sub-second response time (like the one puppet posted) while a 3/16" probe like I am using will have a multi-second response time. check out mcmaster.com in the thermocouple section for a list of probes and their associated response times. plus, like i said, the fact that the probe that came with my autometer gauge is in direct contact (and for about 1/2" of its length) with the METAL exhaust manifold which has a MUCH lower thermal resistance than the exhaust GASES, what I have is an EMT probe...exhaust MANIFOLD temperature probe for instance: I get my egts up to 1500F then let off the gas and put it in neutral...the gauge still reads 1500F and takes about 5 seconds to get down to 1300F...im ABSOLUTELY sure my exhaust gas temperatures arent anywhere NEAR that IMMEDIATELY after i take my foot off the gas

OK...I stand corrected on the probes, just all of the ones I have used myself were alike...A EGT temp will drop immediately when no longer at WOT. I only use large digital units so I can see the temps at a glance and they have a memory of highest EGT during the pass, or lap...until reset or shut off.

[janus]

Hey ATaylorRacing, what gauge do you have?
acanell, did you already receive that probe and how is it working with the autometer EGT, and does the autometer gauge have a background light?
thanks

[acannell]

the autometer does have background light
i have not received the gauge, they never answer when i call, and havent returned my email