Poor-Man's Pyrometer?

[boonsur]

I'm always looking for ways to do things on a limited budget (all my "fun" money makes the payments).

My understanding of a thermocouple is a switch which comes on at a certain temperature. Couldn't we get one and run it to an "idoit" light (buzzer), to come on when a critical temperature (1100-1200*F)is reached?

Would this work? Are their reaction times (on/off) sufficient?

How reliable would thermocouples be for this application? (Can they be easily/regularly tested)?

Could it be mounted in a compression fitting, like the sensor probes for the real gauges? (Then the pipe-tapped hole would already be in-place for gauges, later-on).

Approx. how much do thermocouples cost?

Are there "multi-stage" ones, which could switch another light when say 900* was reached?

Seems like a way to get some degree of protection for under $50. What do you think?

ps: I always let my engine idle for a minute (or longer after a hard pull) before shut-down, so proper cooling-off tempature is not a real big issue.

 

[Cooker]

The only question I can answer for you is that VDO thermocouples are ~$35.

 

[Diesel Freak]

A thermocouple is basicly a bi-metalic strip consisting of two dis-simmilar metals. When these metals are heated they generate a small voltage which is proportional to temperature. Your best bet for a pyro would be one made by ISSPRO.

If you wanted to use a switch to operate an idiot light, I would suggest some sort of thermal snap switch, but I have no clue how to get it into the pre-turbo exhaust stream, or if one exists to tolerate such a harsh environment.
-Cliff

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2001 ETH-DEE, Diablo Power Puck, Bosch 275's, Practical Solutions Boost Module and Elbow, LFT Silencer Ring Eliminator, K&N, Straight Piped http://www.mudrunner.sites.cc

[This message has been edited by cdaledh (edited 05-12-2001). ]

 

[BushWakr - RIP]

On a lighter note, I keep threatening my luvely wife that I'm gonna take the pyro outta the truck and let her use it when she makes meatloaf cause it looks like she's running WAY beyond design spec on that oven!
Hey, a laugh never hurts.
Sorry for being slightly off topic.
Bush'

 

[EMDDIESEL]

Mc Master Carr caries different thermocouples that you may be able to use for your idea. But if the one you choose is not designed to be used in an engine exhaust stream, dont put it Pre turbo.

 

[boonsur]

I didn't realize thermocoulpes give a variable signal. May be more trouble than it's worth to try interpreting the voltage values at various temperatures.

Is there such a thing as a simple temperature-operated switch that might work?

 

[illflem]

Someone posted a link not too long ago that had complete pyros for $54, cheapest I've seen by far, think the brand was Stewart- Warner. I don't remember much else, maybe someone else does.

 

[mongoose]

Illflem, did some checking on the stewart-warner pyros. they have one that retails for 59. 00 and some change. the thing is that it only reads from 300-1500 degrees. they also have a boost guage for about 40. 00. here is the link to the pyro and boost guage. the only problem i see with this deal is that the sender is listed seperatly from the pyro. It is listed as an electric water temperature sender and lists for about 46. 00. that brings the total up to over 100. 00

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Daniel McKeehan

1999 2500 QC/Short Bed/4X4 5 speed. Camper Package and of course a Cummins



[This message has been edited by mongoose (edited 05-14-2001). ]

 

[Bob Wagner]

I have a used/still good thermocouple that I will give you for free or I would also offer to sell you a new TC for my cost which would be 20. 00 -25. 00 w/ ss com fitting.

Let me know if you want the freebie?

Bob

 

[boonsur]

Bob,

Thanks huge for the offer; however, I'm not sure how to calibrate the voltage readings to the actual temperatures.

I may talk to the electrical engineers here at work to see if they have any thoughts.

Still looks like I'll have to shell out the coin.

 

[illflem]

Daniel, You found the right link, I buzzed though it fast and didn't read it completely, that's why I thought it was a good deal. At a around $100 it still is cheap, but I have to wonder about using a water temp sender for a pyro.

 

[rich m]

Originally posted by BushWakr:
On a lighter note, I keep threatening my luvely wife that I'm gonna take the pyro outta the truck and let her use it when she makes meatloaf cause it looks like she's running WAY beyond design spec on that oven!
Hey, a laugh never hurts.
Sorry for being slightly off topic.
Bush'

You're a brave man. If "brave" is not the right word, as Dear Abby says, "Please seek professional help. "

 

[redram]

If the one from S/W reads from 300-1500 F, what more do you require?
below 300 F the truck is shut off and if you ever get over 1300 F for sustained periods, you're beyond what most would consider safe design operational limits. Yes, I know that there are 'bombers' out there claiming / running higher EGT's, but if you're in this league, buy that $400 digital pyrometer to match the $thousands of greenbacks spent modding the truck.

The S/W sounds like it will work just fine.

I use an NGK K type thermocouple that reads from 300-2200 but it was originally purchased for my Wankel race motor (jet the carb for 1550-1700).

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[Hale on wheels]

boonsur,
You could use a thermocouple and send that signal to a comparator, and have that trigger your light, but you would need to figure out the voltage range of the thermocouple and then have a set reference voltage to turn the switch on at the desired temp. It would actually be more trouble to do than a gauge, but I guess it would be cheaper.

 

[R.ebel]

I've wanted an inexpensive EGT idiot light for some time, things happen fast in the heat of battle. Is anybody out there an electronics wizard? This weekend I'll try to get a operational voltage range for the Isspro probe by taking live readings. May also try to contact Isspro for their data on the egt probe.

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1997 2500 SLT 4X4,5 spd,3. 54's,Pacbrake,Rancho 9000's,Centerforce,K&N,Isspro,BD 300 HP pump, Jardine 4", 370's and 16cm housing, blocked dowel pin

 

[Deezal Man]

Maybe this bad example... but I think it is relevent. Additionally, boonser... don't take my thoughts the wrong way, your point is well taken. Just want to point something out... many of us forget.
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I often run across guys who recently purchased new +$10,000 sport bikes.

The conversation turns to helmets and leather riding gear. The normal answer is "thats too expensive" or I can't afford it. #ad


Amazing how they could afford a $10,000 bike, but couldn't afford $1,000 worth of riding gear to save their skin.

The way I see it, the bike can be replaced.

Just ask my buddy who totalled his 2001 ZX-9... . and didn't have a scratch on him because of the leather.

My point being, how can you afford a Dodge Cummins and not afford a gauge?

I'm not saying you have

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98. 5' Emerald Green 24v 2500 Auto/3. 54 4x4 SB QC 285. 75. 16's Bridgestone Dueler A/T's on 16" x 8" Alcoa's under Rancho 9000's. Everything but leather. PIAA 1200's, AMSOIL dual filter relocation system, Smittybuilt Stainless Steel Nerfs, Rhino Liner(Junk).

 

[unclebilly]

Search for EGT on Ebay - the Aviations ones are slick - they are unamplified so they need no extra 12V power.

I got a 2 5/8" EGT that goes from 0 - 1000C for under $15 and it works excellent. It is out of an old wartime plane (complete with NATO #'s) and hence has to be more accurate than a cheap Autometer or Isspro. The Westachs and Alcors usualy gor for under $50.

You can use any K-type probe with them from VDO or ALCOR (www.alcorav.com) or whoever and run the proper chromel / alumel wire (from those guys) or Omega.com. Yes, you can use a swagelok or similar fitting with a shielded probe - I'd get an inconel one.

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91. 5 CTD 4X4, 5" Stacks, Tweaked Pump, 33" Boots (in the summer), Unlimited Slip,
Big, Bad Dodge

 

[Jim Guidry]

If you don't care anything about the low end, (I didn't, I ALWAYS idle for a long time before shutoff), use the Autometer 600f-1500f meter. I got mine for around 60 bucks with a coupon from Carparts, complete w/thermocouple. Works like a champ.

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'96 Regular Cab, 121k, SLT 2WD auto 3. 54, Vista topper, Pillar-mounted Autometer Boost/Pyro, transmission temp and oil pressure guages under dash, starwheel spun, stock plate and housing slid back to stock. Debombed to keep my transmission alive!