xr4tic

I currently have an Autometer "street series" probe in my exhaust manifold, which is located where the #4 and #3 runners join.

I installed a Westach 712-2DWK in the downpipe, and a Westach 712-4D2 in the #4 runner.

Click on any pick for a high-rez version.

The probes:
<a href="http://johnbaas.dyndns.org/audi/EGT_probes.jpg" target="_blank"><img src="http://johnbaas.dyndns.org/audi/EGT_probes_lo.jpg"></a>

Before installation:
<a href="http://johnbaas.dyndns.org/audi/EGT_before.jpg" target="_blank"><img src="http://johnbaas.dyndns.org/audi/EGT_before_lo.jpg"></a>

#4 installed:
<a href="http://johnbaas.dyndns.org/audi/EGT_install.jpg" target="_blank"><img src="http://johnbaas.dyndns.org/audi/EGT_install_lo.jpg"></a>
This just requires drilling into the manifold, and tapping with a 1/8 NPT tap. I let the motor run, and drilled in 4 steps, 1/8, 3/16, 1/4, and the final size which I can't remember right now.
Letting the motor runs helps to blow the shavings out, and drilling in steps keeps the shavings to a small size.

Once it's tapped, then put the fitting in, and then the probe to the desired depth, and then lock it in place. You only get one shot, so don't mess the depth up, it's a Swage-lok fitting, and it crushes the probe to keep it from moving.

DP modification:
<a href="http://johnbaas.dyndns.org/audi/EGT_dp_before.jpg" target="_blank"><img src="http://johnbaas.dyndns.org/audi/EGT_dp_before_lo.jpg"></a>
This clamp is only 2.5" in diameter, so I had to buy another clamp to extend it. I got the clamp from Home Depot, it's stainless steel, just like what came with the probe.

DP installed:
<a href="http://johnbaas.dyndns.org/audi/EGT_after.jpg" target="_blank"><img src="http://johnbaas.dyndns.org/audi/EGT_after_lo.jpg"></a>
Drill a small hole, and clamp it down.

xr4tic

The Autometer (AM) probe was left connected to the gauge, while the other two were read using a voltmeter

At extended idle:
#4 - 700F
AM - 750F
DP - 625F

Cruising low speed:
#4 - 1020
AM - 1150
DP - 950

Cruising high speed:
#4 - 1275
AM - 1400
DP - 1200

WOT:
#4 - 1450
AM - 1600
DP - 1425

Now, here comes the "BUT"

I only had one voltmeter, so I used the AM probe as the reference, and would switch the voltmeter between the other two. The WOT run is a little sketchy, partly because I was keeping my eye on the road, and not the gauge and voltmeter, and also because I don't think it's as accurate as a direct comparison between the DP and #4 probes. The others readings were taken at a steady state of sorts, whereas the WOT was a quick grab reading.

And one more "BUT"

EGT probes work by taking the temp difference between the probe (hot junction) and connector (cold junction)
EGT probes are only accurate at the temperature they are calibrated for at the cold junction (these probes are calibrated at 75F)
For every degree above 75, the probe will read 1 degree low.
For every degree below 75, the probe will read 1 degree high.

Now the cold junction for the two Westach probes was located behind the firewall (battery / fresh air area)
The cold junction for the Autometer probe was in the hot engine compartment, inches away from the exhaust manifold.

This would indicate that the AM readings might be low, and the Westach gauges might be high (it was 50F outside)

I really wish I had two identical voltmeters so I could watch both Westach probes at the same time.

I've got some cheapy datalogger thing for my laptop that has 4 channels. I might have to see if I can get it working.

Phil type 951

nice work.... what about a switch to change probe readings on the gauge?

Audiboy

cheapy data logger? where'd you get one? I've been looking for a cheapy one myself

WYSIWYG

woah, you work fast

WYSIWYG

i got one off ebay(new) for $39. 1sec sampling rate. uhh were talking about VOM+temp right?

Audiboy

faster will be nicer ;P I was disecting the GTech to try to add a datalog port - before the second G-Tech thing came around. Now, I need to datalog two-three MAF's at the same time, while looking at other things. What brand is yours? Hmmm, why didn't I look in EBAY

Audi2ptzero

<center><img src="http://www.jegs.com/photos/2484105.gif"></center><p><ul><li><a href="http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=138953&amp;prmenbr=361">cli ck here</a></li></ul>

WYSIWYG

i believe craftsman has it for $90-110. mine's MASTECH MAS-345 + PC interface

xr4tic

I got the starter kit, mines at least 3 years old, so there are newer versions out.

10 bit, +/-10V, 4 channels, and up to 240 samples a second, all for a whopping $25<ul><li><a href="http://www.dataq.com">http://www.dataq.com</a></li></ul>