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Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
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 Posted: Wed Jan 20, 2021 7:51 pm Post subject: |
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How are you going to get the thermocouple ends into the air intake system? You can't bolt to the outside. The wire will need to penetrate a hose or something to be in the flow of air.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Cedric
Joined: 27 Aug 2004
Posts: 2610
Location: Sweden
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| Posted: Wed Jan 20, 2021 10:09 pm Post subject: |
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It depends on what thermocouple it is, but in general the accuracy for these types of measurements isnt that good, they are normally designed for higher temp applications, but probably enough for a reference value, if you can get a good sensor placement. The biggest hurdle can be the response time, which highly depends on the diameter of the sensor tip, not an issue if you do a bonneville run, but if you try to measure things on the roads it can be a big challenge, an open tip sensor type is highly recommended. I have been doing engine testing on road and test cells professionally and have battled with this a couple of times 
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1980 924 Turbo
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Wed Jan 20, 2021 11:02 pm Post subject: |
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| Carrera RSR wrote: | | How are you going to get the thermocouple ends into the air intake system? You can't bolt to the outside. The wire will need to penetrate a hose or something to be in the flow of air. |
Option 1 - overboost port on intercooler
Option 2 - existing S2 temp sensor location
I have the metric adapters to try both locations.
From another thread but relevant
| lildude4life wrote: | Quote:
New IAT in the cold side of the TMIC as well as the brake booster line:
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If the thermocouple isn't accurate or is too slow I’ll look into a different setup. 
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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Fasteddie313
Joined: 29 Sep 2013
Posts: 2596
Location: MI
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| Posted: Mon Jan 25, 2021 2:30 am Post subject: |
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If your AFR is like 11.7 and lower, down to about 10.5 max, I wouldn’t really even worry about your IAT until you are pushing over 15psi..
That IC should do fine for moderate boost..
If you ever decide you need a faster air temp sensor, that sensor you have there would still be excellent for a liquid temp sensor, like coolant, oil pan, ic coolant fluid.. Something like that..
Sensor in that pic above looks like an open element GM sensor, like I have..
I still think it is too slow and too susceptible to heat soak from whatever it’s screwed into..
I’m gonna read your link and see if it has anything on superior options..
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80 Turbo - Slightly Modified |
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Thu Jan 28, 2021 5:31 am Post subject: |
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| Fasteddie313 wrote: | If your AFR is like 11.7 and lower, down to about 10.5 max, I wouldn’t really even worry about your IAT until you are pushing over 15psi..
That IC should do fine for moderate boost..
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I think that 15psi would be the max. The car seems pretty quick at 12psi.
I'm curious to see the temps on boost. At some point I might ad another sensor before the intercooler to see what's really going on.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Thu Jan 28, 2021 5:34 am Post subject: |
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I received the gauge panel today...hope to get everything installed this weekend.
 
 
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lildude4life
Joined: 27 Apr 2015
Posts: 60
Location: Milwaukee WI
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| Posted: Fri Jan 29, 2021 9:19 am Post subject: |
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| chuck21401 wrote: |
I'm curious to see the temps on boost. At some point I might ad another sensor before the intercooler to see what's really going on. |
Chuck, this was from last fall before the weather turned junk. Only at 8.6psi, but it shows pre and Post IC air temps. IC took temps from 98F pre, to 85 which was both ambient and IC water temp. You can see the pre IC temps rise a bit towards the end of the graph. It works quite well.
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"931 EFR" 81 931 S2 w/ EFR 6258 turbo, EFI, Haltech Elite ECU, 240whp |
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Sun Jan 31, 2021 3:08 pm Post subject: |
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| lildude4life wrote: | Only at 8.6psi, but it shows pre and Post IC air temps. IC took temps from 98F pre, to 85 which was both ambient and IC water temp.
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Cool. But to tell you the truth I was expecting something a bit more dramatic...but at relatively low boost levels I'm guessing there's not as much heat to remove?
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler
Last edited by chuck21401 on Sun Jan 31, 2021 3:19 pm; edited 1 time in total |
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Sun Jan 31, 2021 3:14 pm Post subject: |
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I was able to get the intake air temperature sensor and gauge installed today.
Here's the thermocouple - 1/8 NPT fitting into a M12x1.5 adapter. (source: https://www.racetronix.biz/p/adapter-1-8-fpt-m12x15-male/adf-18fpt1215m)
I routed it under the throttle body.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler
Last edited by chuck21401 on Sun Jan 31, 2021 3:34 pm; edited 2 times in total |
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Sun Jan 31, 2021 3:16 pm Post subject: |
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I attached the bracket to the shelf under the glove box.
Here's the temp before I started the car. 40F
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Sun Jan 31, 2021 3:27 pm Post subject: |
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I went for a drive and I'm surprised by the readings. The air temperature was about 33 degrees and the intake temperature stayed in the high 40s most of the time.
I did a handful of WOT runs and the temp went up to low 50s. Max boost was 9/10psi.
Interestingly, the highest temperature I noticed was idling in the driveway for a couple of minutes before shutting it down....56 degrees.
I was expecting to see dramatic increases in the intake temp on boost...at least into the 70/80s or something.
Tomorrow I'll turn up the boost and go for another run.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Mon Feb 01, 2021 12:58 am Post subject: |
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Inter-equalizer instead of Inter-Heater 
Nice! I always felt the '82 did something like this in that the intercooler was still being cooled when idling (by hand test...totally unofficial). For how long that holds I have no idea
Have to keep pushing on my two with this intercooler to add to the collective data
I don't drive mine in winter anyway and there is a bunch of snow on the ground right now and still falling
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Carrera RSR
Joined: 08 Jan 2010
Posts: 2309
Location: Somerset, UK
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| Posted: Mon Feb 01, 2021 4:58 am Post subject: |
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Would you bet the value of an engine rebuild on those temps being accurate??
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Tue Feb 02, 2021 12:22 am Post subject: |
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What were the ambient temps during all these test runs?
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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chuck21401
Joined: 20 Feb 2005
Posts: 530
Location: Annapolis, MD
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| Posted: Tue Feb 02, 2021 4:36 am Post subject: |
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| Mike9311 wrote: | | What were the ambient temps during all these test runs? |
I don't have a lot of reliable data to report. I took one 30 minute ride Saturday night and then a rare snowstorm hit the DC area so the car is stuck in the garage.
re:ambient temps
Don't know. The outside air temperature was 33 degrees when I checked, though I believe ambient air temperature is the temperature at the air filter.
Corky Bell's book suggests several places to check temperature and pressure. I have one thermocouple on the cold side of the intercooler and I'm not sure what to make of the temps I was seeing.
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1981 Porsche 931 w/S1 engine & g31 transmission. Water-cooled intercooler |
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