lets all figure out how to make a fast EGT probe

[janus]

hmm that sux. is there any other dependable digital gauge that is both affordable and has a good response time? i want a digital one so bad!

[JMVegas]

Why are you guys so worried about egt's anyways?? Egt gauges should be glanced at after the wide band. Mine reads slow and I don't give a damn, my wide band is instant, and so is my knock sensor. Those 2 are more important than a egt. Egt's just back up what the wide band and knock sensors are telling me.

[janus]

JMVegas, how do you visualize the knock sensor output? sounds like a good way to go, too. i know that we all, but especially me, keep learning new stuff every day
[offtopic]
i have a zeitronix wideband system kicking around, but dont have a gauge for it yet.. could i hook up my narrowband gauge to the analog output port?[/offtopic]
thanks

[acannell]

wow...i have some juicy things on this topic:

first off, this article is CHOCK full of grade-a info on egt probe and gauge response times. this guy took several probes and measured their response time without a gauge, then took a bunch of gauges and measured their response time with a fixed input voltage. VERY interesting.

http://www.turbodieselregister.com/EGT_EVAL.pdf

second, the teamrip.com exposed tip EGT gauge seems to be impossible to get. those people never answer the phone or email in more than a week. so I bought one from here instead:

EGT Gages

its got a 12' cable. kinda expensive at 79$ + s/h but oh well

seems like quite a few people sell exposed tip egts gauges..just google "exposed egt probe" and you will get lots of hits

I think an engines EGT provides valuable info for tuning and diagnostics, and as a warning to transient problems that could lead to severe damage. I'm pretty sure you could have excessively high EGT's even with a good AFR and no knock. Plus I don't want any gauges in my car that are useless, and right now my $150 autometer EGT gauge and probe are worthless for seeing anything at WOT.

[janus]

wow that's a bunch of NICE infos right there. thanks for digging into that and sharing this with us. needs some reading though

anyways, as i have a zeitronix system that also supports EGT i'm also in the progress of choosing a probe.
on the zeitronix site they have one for 85$ which they claim very fast (of course, lol) and this are the more specific infos i got as a reply via email:

Quote:

T/C going from 0 to 100 C, it will take approx. .40 seconds to reach 66.66 C, .40 seconds more to get to 88.88 C and .40 seconds more to get to 96.29 C and so on for a total of 7 time constants to reach 100% of the change. This means that to see the settled temp at 100 C it would take a total 2.8 seconds for the total 7 time constants at .40 seconds each. Realistically, you are at 96.29% of the step change in 3 time constants or 1.2 seconds. In other words this is very low mass and fast EGT probe.

any opinions on this? i'm a bit confused about the numbers might be helpful for somebody looking into buying a zt-2 and thinking about their EGT probe (8' cable) as well. as said, 85$ + s/h is still kinda daylight robbery, but i havent compared it to other probes by the # yet. so it might be still worth getting this one while your at ordering your zt-2 anyway.

maybe someone on TD has this probe in use and has some comments for us otherwise, any comments on the #s?
i will also have a look at the rjc site.

thanks

[acannell]

okay got the exposed tip probe from rjc today and installed it..used an omega HH11 digital thermocouple meter to watch the EGT while driving

turns out I am peaking at 1690F at WOT

the probe is VERY nice and looks like $80. it has Omega engineering stickers on it so its a custom omega thermocouple. responds faster than the omega meter which updates 2.5 times per second. NICE.

[jim34]

Your old probe was simply no good.

[acannell]

yeah no good in that it was slow. it worked just fine just had a very long time constant.

it was a brand new autometer gauge and probe and indicated correct temperatures at idle and cruising.

[ShiftB13]

Quote:

Originally Posted by speeduphoria 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

me too!

[turboAMX]

Placement of the egt probe is critical for correct reading. You need to have approximately 6 inches from the exhaust valve to the probe location. Closer or farther away can lead to inpropper readings due to fuel burn and flame travel.

[detobias]

there are many many different types of (thermocouple) probes available - the 'Mitsubishi' weblink features an exposed junction style which will have a fast response, but may have a shorter life

some EGT gauges are rumored to have a "delay" built into them ; it would be trivial to see if your gauge is that style - an EGT gauge is quit simple a 0-2volt gauge (much like an O2 gauge is really a 0-1v gauge)

(do I have to spell out how you would check yur gage ?)

check out omega.com for a staggering amount of info and choices in thermocouples ; they specialize in that stuff and there is oodles of info on their (poorly designed) website

my eBay thermocouple combined with my "BanksPower" gauge also has a approx 5-7 sec lag time