Author Topic: EGT Probe question (Read 19064 times)

saurkraut · « **Reply #45 on:** November 17, 2006, 10:11:17 am »

The opinion in this "discussion" is that post turbine may be a valid measurement.

There is no one here that has taken the time to mount two probes and record the data.

Slave2school offered to get the data for you for 50 bucks.

Pre turbine measurement is proven to be valid and is currently used and endorsed in this application. It has been field tested, and there is no evidence of probe failure in this application.

jackbombay · « **Reply #46 on:** November 17, 2006, 10:12:30 am »

Quote from: "larry104"

jackbombay, I don't know you. But I'm not trying to convince anyone or put people down. I just have a tough time accepting something without solid proof. I'd simply like to see numbers to back up the claims. :mrgreen:

Inaccurate gauges drive me nuts, subtracting a theoretical 200* degrees to determine the turbine inlet temp is not my deal, why not measure the actual parameter you are interested in? It's more work, and there is a minuscule risk of probe failure, we weight those factors differently.

larry104 · « **Reply #47 on:** November 17, 2006, 10:14:33 am »

Quote from: libbybapa

Oops, yup, 1600. Nice irrelevant nit to pick there. Regardless, everything else I posted stands. 1600 and you're likely in trouble and not from your probe. Are you really not getting it? Or just trying to prolong the attention your getting?

Andrew

Andrew, as I said, 1,600 F with negligible vibration. VW diesels vibrate, alot, which can fatigue certain metals at elevated temperatures, though as you say max temps are lower than what I was working with. You know much more about diesels than I do. I'm learning, and Ilike to base decisions on facts, not anecdotal information. Sorry.

HarryMann · « **Reply #48 on:** November 17, 2006, 10:33:00 am »

Larry,

Don't be sorry, this has proved an inspirational opportunity to moot pros and cons on an abstract subject that doesn't really affect any of us much... and keep away from more meaningful stuff

just so happens I'm ordeing an EGT setup now, in the UKk, and have given the specs to my man and he's sourcing what he thinks is the best he can get for my application: I'll either say Yes or say No when I hear his proposals, but none of them sound expensive c.f. the Aircraft Spruce or other US offerings..

I've quoted 1650F for a pre-turbine placement, gauges to suit, length of wiring extended to suit - and they supply to light aircraft owners mainly.

Hopeful, and having manifold off, will drill where I think fit M8 thread and pray....

larry104 · « **Reply #49 on:** November 17, 2006, 11:04:14 am »

Quote from: HarryMann

Larry,

Don't be sorry, this has proved an inspirational opportunity to moot pros and cons on an abstract subject that doesn't really affect any of us much... and keep away from more meaningful stuff

just so happens I'm ordeing an EGT setup now, in the UKk, and have given the specs to my man and he's sourcing what he thinks is the best he can get for my application: I'll either say Yes or say No when I hear his proposals, but none of them sound expensive c.f. the Aircraft Spruce or other US offerings..

I've quoted 1650F for a pre-turbine placement, gauges to suit, length of wiring extended to suit - and they supply to light aircraft owners mainly.

Hopeful, and having manifold off, will drill where I think fit M8 thread and pray....

Thanks, and good luck with your EGT installation.

HarryMann · « **Reply #50 on:** November 17, 2006, 11:58:57 am »

No, unfort. aircraft gauges seem to read down to about 400C and thats it, as I say, they're more interested in steady state soak temps than much else. As long as the top end goes up high enough, I'll be happy... some even only have a 4 to 9 range, 400 to 900C

Buit bet they're pretty accurate within that range

Slave2School · « **Reply #51 on:** November 17, 2006, 12:38:35 pm »

The westach gauge I have reads from 100F-1900F

HarryMann · « **Reply #52 on:** November 17, 2006, 02:51:17 pm »

Thats handy to know when my source gets back to me... 100~1900, nice wide range that.

Slave2School · « **Reply #53 on:** November 17, 2006, 02:57:53 pm »

This is exactly the one I got.

http://aircraftspruce.com/catalog/inpages/westegt2.php

larry104 · « **Reply #54 on:** November 17, 2006, 02:59:55 pm »

Quote from: HarryMann

Thats handy to know when my source gets back to me... 100~1900, nice wide range that.

I have a Westach combo EGT/boost gauge that reads from 100 to 1500 F.

http://www.genosgarage.com/prodinfo.asp?number=WM-CG-8

larry104 · « **Reply #55 on:** November 17, 2006, 03:03:22 pm »

Quote from: jackbombay

Quote from: larry104
jackbombay, I don't know you. But I'm not trying to convince anyone or put people down. I just have a tough time accepting something without solid proof. I'd simply like to see numbers to back up the claims. :mrgreen:

Inaccurate gauges drive me nuts, subtracting a theoretical 200* degrees to determine the turbine inlet temp is not my deal, why not measure the actual parameter you are interested in? It's more work, and there is a minuscule risk of probe failure, we weight those factors differently.

These EGTs take away some of the guesswork. Green good. Red bad.
http://www.genosgarage.com/prodinfo.asp?number=ISS-R3607VWR
http://www.genosgarage.com/prodinfo.asp?number=ISS-R3607TR

larry104 · « **Reply #56 on:** November 17, 2006, 03:17:23 pm »

Quote from: saurkraut

You are right. No one has mounted two thermocouples on their engine and recorded these measurements. I doubt anyone ever will, except Slave2School. He clearly offered to do it for fifty bucks. So there is a valide offer to produce the data you desire.

I might just take him up on that! :lol:

Turbinepowered · « **Reply #57 on:** November 17, 2006, 03:20:49 pm »

Quote

These EGTs take away some of the guesswork. Green good. Red bad.
http://www.genosgarage.com/prodinfo.asp?number=ISS-R3607VWR
http://www.genosgarage.com/prodinfo.asp?number=ISS-R3607TR

So... they shifted the "yellow" zone back some. That's not going to make your sensor react any more quickly, and if you sustained right at the edge of the yellow in the post-turbine setup (~900F) you would be well into the yellow range of the preturbine setup (~1100F), if it's a straight-shot 200F drop across the turbine.

You said you're doing some calculations; what data are you using in these calculations? Turbo efficiencies, ratios, sizes, engine RPMs, even fuel type used? Boost pressure? Intercooled or non-intercooled; there's a whole lotta stuff that goes into determining EGTs, and a whole lot more that determines how much temperature drop you get across any given turbine.

Personally, I'd rather not "guess" anything at all. If I had the money, I would be monitoring each individual cylinder's output. And each individual cylinder's input, too, black-box style. I am sorely tempted to find a temperature guage that would let me monitor input temps... if only because that would be a cool way to prove some intake cooling mods I'd like to try.

Slave2School · « **Reply #58 on:** November 17, 2006, 03:39:24 pm »

I thought about getting this just so it could be done easily (each cylinder) http://aircraftspruce.com/catalog/inpages/aerospace_logic.php but the need to eat out weighs the novelty.

larry104 · « **Reply #59 on:** November 17, 2006, 04:42:06 pm »

Quote from: Turbinepowered

Quote
These EGTs take away some of the guesswork. Green good. Red bad.
http://www.genosgarage.com/prodinfo.asp?number=ISS-R3607VWR
http://www.genosgarage.com/prodinfo.asp?number=ISS-R3607TR

So... they shifted the "yellow" zone back some. That's not going to make your sensor react any more quickly, and if you sustained right at the edge of the yellow in the post-turbine setup (~900F) you would be well into the yellow range of the preturbine setup (~1100F), if it's a straight-shot 200F drop across the turbine.

You said you're doing some calculations; what data are you using in these calculations? Turbo efficiencies, ratios, sizes, engine RPMs, even fuel type used? Boost pressure? Intercooled or non-intercooled; there's a whole lotta stuff that goes into determining EGTs, and a whole lot more that determines how much temperature drop you get across any given turbine.

Personally, I'd rather not "guess" anything at all. If I had the money, I would be monitoring each individual cylinder's output. And each individual cylinder's input, too, black-box style. I am sorely tempted to find a temperature guage that would let me monitor input temps... if only because that would be a cool way to prove some intake cooling mods I'd like to try.

Turbine delta T depends on turbine inlet temp, pressure ratio across the turbine, turbine efficiency, and the ratio of specific heats, which I am assuming is air (k=1.4). Mass flow into the turbine is what flowed into the compressor and engine, plus fuel. The air portion can be gotten from a turbo map. Engine air demand (flow rate) scales with rpm and displacement. Compressor power demand scales with boost pressure ratio, flow rate, and compressor efficiency. Intercooler efficiency, depending on the intercooler, is a published number. No, I haven't measured IC delta Ts. Again, all this is rough. I need to double check things and, ideally, verify the results with some real data.