This is data collected for another thread in the EFI section, but thought it interesting to those who might not look into an EFI thread.

These temps were taken with a spot temp sensor which required a color balancing process which I did not do. So absolute temps may be a bit off, but you can assume silver things are correct relative to others, and black things are also correctly related to other black things. I was more interested in comparing these temps to later readings after making mods to deal with heat build up in the fuel. The first fuel rail readings I took, before moving the fuel rail around to keep it away from heat were in the 195 range.




After relocating the fuel lines to keep them away from hot stuff, I took the car for a ride and made the following observations when I got back:

1. The fuel rail is cooler, (see below) but the fuel pressure is still falling with raise in temp.
2. However, the AF ratio was more stable. It never went into the hyper lean mode. It went from idle of 13.5 to idle of 14. 1, but cruising the O2 sensor seemed to correct to keep it cruising at 14.8-15.1:1.

When I got back I took measurements of temps on lots of stuff, and here is the results:
1. Fuel rail rear..........................144
2. Fuel rail front..........................150 (turbo is closer here)
3. PFR....................................... 114
4. Turbo Exhaust flange...............249
5. Turbo housing.........................424
6.Intercooler..............................125
7. Master cylinder.......................113
8. Top Radiator hose...................179
9. Thermostat housing ................216
10.Intake manifold .....................175
11. TB delivery tube....................125
12. TB........................................152
13. Fuel line delivery, ..................131
14. Pass inner fender...................106
15. Drivers inner fender...............110 (turbo is on this side, but is vented also)

Sam

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Sam
What was Ambient and what kind of day Sunny etc.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

The temperature was 75 degrees, and the sun was down at 9:20 PM.

Sam

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The "color balancing process" is probably their way of adjusting for emissivity. Emissivity is a property of the material, surface condition, and geometry.

Ambient temperature is much less important than reflected energy - What's reflecting how much IR energy off a given surface into your sensor, along with the IR energy you're actually interested in?

Assuming that emissivity is the same and therefore that readouts are comparable just because of colors are similar is VERY iffy, especially for infrared-reflective (low emissivity) surfaces, such as bare metal, metallic paints, etc. It's much closer if you know that the surfaces are the same material and condition, such as if you had painted them with the same kind of paint.

Spot meters have their place, but you can fool yourself badly.

I wish we could get a thermographer to take a look ...

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

I'm actually more interested in before and after readings on the same object. But I do appreciate the education there. Thanks. How far off do you think the readings would be without emmissivity calibration?

The bottom line is that the problem with the fueling that lead to all this checking has been uncovered. The electronic fuel pressure gauge in the dash was way, way off. Once I got a good mechanical pressure gauge in the system I found out I had the FPR set for 80 PSI.Of course I did not know that, because my inside gauge was wrong. Once I readjusted the FPR, and retuned the fuel map, it is no longer subject to the warm up instability I had been experiencing.

However, I am going to continue building heat shields and such to bring the fuel rail temp down.

Sam

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Without considering emissivity, temperature differences could easily be off by, say, a factor of five.
One easy way to improve accuracy would be to put targets of known, high emissivity on the spots you want to check. Put a patch of electrical tape on the spots you want to check. Make sure that the target size is bigger than the spread of the sensor. It'd be good to put them in repeatable places for future comparisons. That way, emissivity of each point is the same, and reflectance is low.
Good quality vinyl electrical tape has an emissivity of about .95 - pretty good for the way most spot temp guns are set. It's thin, and heats up quickly, so it's very close to the surface temperature of the part. Tape is also cheap, you get a lot of targets out of a roll, and it comes off easily. Higher temperatures could be a problem. I've used it a little past 100C/212F with no problem, but it's going to burn at some point.
Spray foot powder is also useful, believe it or not. I haven't tried it at higher temperatures (exhaust manifolds, turbos, etc).

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

Differences off by a factor of five, or temperatures off by a factor of five? All the readings seemed completely logical and in agreement with what my hand told me and the ECU's readings of the sensors. The hand held gauge read 216 for the thermostat housing, and that is just a few degrees off from what the laptop readout was for the sensor just and inch away from it. I just need to know if things are getting cooler. Readings on the same parts seem to be consistent from reading to reading, so that should work for my purposes.

Sam

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I'll tell you what I will do to improve this information. At some point in the future I will take a piece of tape and put it on all the surfaces that will not melt it off, and repeat the readings at some point. Off course things will have changed by then, so we won't know for sure the effect of the tape, but we will provide a little more accurate info for the forum members.

Sam

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I'm glad your numbers seem to be good. The surfaces you're looking at may well be close enough that you get useful information. I love the detail you're giving us on your project, BTW.

Please do post what you find!
Differences. A lot of the less expensive devices don't read in absolute temps (Kelvin or Rankine). Remember, a 10% reduction from 200F does not yield 180F, unless you're in advertising.

Do be careful on the shiny places, to note what might reflect on them. IE, If you bounce a laser off that surface from where you're looking, what does the laser hit? I sometimes use that technique to check temperatures on surfaces I can't directly see.

I only bring these things up because, as a thermographer, I sometimes see decisions being made with flaky data. One magazine article on VW engine cooling comes to mind. Using a typical IR temp gun with a laser pointer, they made no mention of varying materials or adjusting settings, or of using consistent measurement points and angles. They were comparing temperature readings taken on stock painted valve covers with readings taken on polished aluminum valve covers, and congratulating themselves on dropping oil temperatures. They might or might not have done any good, but their report didn't prove squat. GIGO.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

I get your point. I will watch for that.

Sam

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