Considering an EGT gauge...which manifold cylinder runner should i plumb the probe into?
03-05-2003, 04:14 PM
#1
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Considering an EGT gauge...which manifold cylinder runner should i plumb the probe into?
Which cylinder runs hottest?
Also...i was thinking a A/F and a EGT would both be useful...but if im not experimenting (sticking with the standard T28 kit software) then only an EGT would be useful... (because i won't have to worry if im leaning out since im not changing variables.)
Cheers,
Sameer
Also...i was thinking a A/F and a EGT would both be useful...but if im not experimenting (sticking with the standard T28 kit software) then only an EGT would be useful... (because i won't have to worry if im leaning out since im not changing variables.)
Cheers,
Sameer
03-05-2003, 05:40 PM
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well...
you can go right in front of the turbo at the collector point... that is ahead of the turbo and technically more accurate... the other option is in front of the cat... but that is POST turbo and thus not as accurate cause those temps will fluctuate based on turbo temps. I have heard that post turbo EGTs are 100 degrees lower... but that wasn't on an audi board, and that is by no means an absolute.
since I have the pic handy, this is john's ATP manifold... (look around johns head and my hair)
<IMG SRC="http://rt.fm/~jcs/media/events/2003-03-01_apr_bbq/img_1891.jpg">
you can see the hole on the bottom of the exhaust manifold... ask him what he thinks...
if you are going to get an A/F, I hear people say that a wideband unit is the only way to go. I haven't looked into A/F things yet, so I don't know much about them yet...
since I have the pic handy, this is john's ATP manifold... (look around johns head and my hair)
<IMG SRC="http://rt.fm/~jcs/media/events/2003-03-01_apr_bbq/img_1891.jpg">
you can see the hole on the bottom of the exhaust manifold... ask him what he thinks...
if you are going to get an A/F, I hear people say that a wideband unit is the only way to go. I haven't looked into A/F things yet, so I don't know much about them yet...
03-05-2003, 07:48 PM
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behind the turbo especially autometer gauges else you might be reading past the grading
to me *exact* reading is useless if the gauge is not tunable. as long as you know the average reading you'll have a reference point ... ex +200deg @aggressive street or maybe +350deg@all out track conditions. i've set to back off at 1450 at this point - thats the probe(autometer) behind the turbo
also this is my 2nd probe - i guess it cant handle turbo temps very well. just my .02
also this is my 2nd probe - i guess it cant handle turbo temps very well. just my .02
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03-05-2003, 08:05 PM
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so....
I am confused and not so educated in terms of EGT.... your point is totally valid, cause if you can't tell that you are 200degrees too hot, than it won't do you any good...
are you saying that the turbo stabilizes the temps enough to read? I am not sure what you mean by grading?
are you saying that the turbo stabilizes the temps enough to read? I am not sure what you mean by grading?
03-05-2003, 08:19 PM
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same q, since EGTs rise with RPM presumably...
so your median is a sliding scale? So are you using a digital gauge that just reads additional EGT beyond your pre-set baseline?
Cheers,
Sameer
Cheers,
Sameer
03-05-2003, 08:58 PM
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My $0.02 worth....
Take it for what it's worth.
An EGT is a better tool than the A/F ratio gauge. You want it before the turbo. The EGT gauge is a good indicator of heat energy going into the turbo, why would you want to put it after it?
Plus, EGTs that are too high can damage the turbo, again, if the probe is after the turbo, you have no idea what your actual EGT is.
Mine is located between 3 and 4, it's the big hole on the manifold in the pic that Bryan posted. It's supposed to be for an external wastegate, but I use an internal, so it was a convenient spot for a probe.
FWIW, at cruising speeds, I see EGTs in the 1450-1500F range, which seems too high to me. It may be a bad probe though.
An A/F gauge would be nice as it can indicate serious lean conditions a little easier than an EGT (if you don't see the green lights come on at WOT, you're lean) It's only good at WOT. My car was running over 25% rich, and still the O2 values cycled up and down according to VAG-COM, so there is no way I would've been able to tune part throttle by using an A/F meter
An even better solution would be a wideband O2 sensor, but they're $$$$$$
An EGT is a better tool than the A/F ratio gauge. You want it before the turbo. The EGT gauge is a good indicator of heat energy going into the turbo, why would you want to put it after it?
Plus, EGTs that are too high can damage the turbo, again, if the probe is after the turbo, you have no idea what your actual EGT is.
Mine is located between 3 and 4, it's the big hole on the manifold in the pic that Bryan posted. It's supposed to be for an external wastegate, but I use an internal, so it was a convenient spot for a probe.
FWIW, at cruising speeds, I see EGTs in the 1450-1500F range, which seems too high to me. It may be a bad probe though.
An A/F gauge would be nice as it can indicate serious lean conditions a little easier than an EGT (if you don't see the green lights come on at WOT, you're lean) It's only good at WOT. My car was running over 25% rich, and still the O2 values cycled up and down according to VAG-COM, so there is no way I would've been able to tune part throttle by using an A/F meter
An even better solution would be a wideband O2 sensor, but they're $$$$$$