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stugray
I searched a lot, but cannot find many hits on "Exhaust gas temp".
I figured there would be some in the garage and the paddock, but no.

So, I am planning on running a "mostly" stock 2.0L 71-914 in Rocky Mountain Vintage Racing (RMVR) with dual carbs & Raby Cam.

I have upgraded headers w/ Supertrapp tip instead of the stock HEs.

Questions are:

1 - What temps are considered "normal" and which are "out-of-spec"?

2 - I hear that the distance from the exhaust port to the probe makes a huge difference in temps measured.
Any help in deciding where to position the probes would be great

3 - I also see the different probes: Welded bung w/ thread in vs drill a hole and stick in probe with clamp method.
Any thoughts on that?

Any help would be great.

Stu
wndsrfr
Stu...you've seen my mounting--attached pic below--about 1 inch down from the Tangerine's "stingers" so they're about 3 1/2 inches from the head port itself. The probes are from "the sensor connection" & those guys are great to work with--replaced one that worked loose no charge. (BTW, get the 12 foot leads, you'll need it.)
I put in a 4-channel & it's a hoot to watch the display under various driving conditions. At idle I'll have 1000F on two cylinders that have a good mixture and 400F-600F on the two that don't. Bear in mind I have these huge TB's and the slightest mismatch of the throttle plate in there makes a huge EGT difference at idle or very small throttle openings, which is most of the cruising under 55mph. Does it matter? Don't think so since there's basically no load on the engine with the throttle barely cracked.
Now, at WOT at the track, I'll see about 1300F on all 4 with maybe 50F difference across them. Jake says to look for no more than 1275 at WOT and that's what's really important 'cause that's when max load is there and max damage if something is wrong.
Interestingly, EGT's go much higher--well over 1500F when feathering the throttle at high rpms--say expressway at 75mph in 4th & holding it steady so it's taching maybe 4500-4800rpm. Again, not much load on the engine, so probably no cause for alarm but sure do want to hear the experts take on it....
stugray
wndsrfr,

Thanks!
Your pics were the inspiration for me deciding to get the 4-channel just like yours.
If I get the poke in probes, I can make them myself.
To try to make the thread in ones, I would need to know what kind of potting they use at those temps.
I am sure I can get whatever they use as I am in aerospace, and we throw away gallons of various potting compounds daily.

I appreciate the feedback and the ~temps at load and no-load conditions.

I frequent the forums at Jakes site, so I'll poke around there some more.

Any link to threads where you discussed it would be great.

Stu
wndsrfr
To try to make the thread in ones, I would need to know what kind of potting they use at those temps.


Stu...I got the bungs along with the probes from the sensor connection folks...drilled the headers with 3/16" holes for the probes & took it to my muffler shop where they welded the bungs in for like $20 total.....took like 10 minutes.
ChrisFoley
QUOTE(stugray @ Nov 29 2011, 10:18 PM) *

wndsrfr,

Thanks!
Your pics were the inspiration for me deciding to get the 4-channel just like yours.
If I get the poke in probes, I can make them myself.
To try to make the thread in ones, I would need to know what kind of potting they use at those temps.
I am sure I can get whatever they use as I am in aerospace, and we throw away gallons of various potting compounds daily.

I appreciate the feedback and the ~temps at load and no-load conditions.

I frequent the forums at Jakes site, so I'll poke around there some more.

Any link to threads where you discussed it would be great.

Stu

I sell specially customized 4 channel EGTs made by Aerospace Logic, with the clamp on style probes.
The clamp on style is convenient to install with the header already on the car.
I've used them for many years with no problem.

The thread in style are usually 1/8"NPT. Half-couplings are welded onto the header.
The fitting on the probe is actually a slip-on 3/16" compression fitting, no potting compound used.

The ideal probe location is 4-6" away from the back side of the valve.
As mentioned above, the temp will vary widely with throttle. The only place where tight control over exhaust temp is necessary is at WOT, however temps at other throttle settings can be of value for diagnostic purposes.
If you are looking for detailed info regarding exhaust gas temps and what they mean, search the internet for aircraft related articles.
stownsen914
I've used EGTs on my 914/6 (and a 4 before that) for years. When I asked a couple racers what temps to look for when I first starting using an EGT, they told me to aim for 1200-1300 degrees F at WOT. To be safe I usually aim for closer to 1200. It seems to leave a nice color on the exhaust outlets and on the plugs, for whatever that's worth.

Scott
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