Home » Public Forums » GMCnet » New egt and tranny temp gauges
| New egt and tranny temp gauges [message #261224] |
Sun, 07 September 2014 18:33  |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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I installed a new egt and tranny temp gauge prior to camping this weekend. I wanted to get a baseline before towing a car. The tranny temp sensor is in the pan and the egt is in the left exhaust pipe just after the header. The transmission holds at about 125F to 150F on level ground at 65 mph. The egt holds right around 1200F cruising at 65 mph and gets up to 1350F going up hill. I'll have to see what it does with 4500 lbs in tow.
I also plan to measure the header temp at the head to see how much the egt cools before reaching the sensor at the collector.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: [GMCnet] New egt and tranny temp gauges [message #261225 is a reply to message #261224] |
Sun, 07 September 2014 18:45  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Jerrod,
When you get those differential egt's, please be sure to post them.
Perhaps they'll help me become more comfortable with the high egt's I'm
seeing just downstream of the Cad500's manifolds. Your 1350*F is already
somewhat comforting -- at least it's higher than the 1200's Randy and
George see. I'm still seeing up to 1400*F+ at 65 mph cruise -- not towing.
Ken H.
On Sun, Sep 7, 2014 at 7:33 PM, jerrod winter wrote:
> I installed a new egt and tranny temp gauge prior to camping this
> weekend. I wanted to get a baseline before towing a car. The tranny temp
> sensor is
> in the pan and the egt is in the left exhaust pipe just after the
> header. The transmission holds at about 125F to 150F on level ground at 65
> mph.
> The egt holds right around 1200F cruising at 65 mph and gets up to 1350F
> going up hill. I'll have to see what it does with 4500 lbs in tow.
>
> I also plan to measure the header temp at the head to see how much the egt
> cools before reaching the sensor at the collector.
> --
>
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Ken Henderson
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: New egt and tranny temp gauges [message #261231 is a reply to message #261224] |
Sun, 07 September 2014 19:43 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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I was told by an engine builder friend of mine that the surface temp of the header pipe near the head is very close to the egt if under steady state conditions. I was planning on using a contact probe to measure temp of all 8 outlet pipes with the tranny in gear and about 1500 rpm.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: New egt and tranny temp gauges [message #261317 is a reply to message #261224] |
Mon, 08 September 2014 18:03 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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I measured the outlet pipe surface temp very near the head with a fluke contact surface probe. The surface temp can tell you if you have a jug out of line but it doesn't indicate actual egt temp well. Surface temps were between 375 to 450 F while indicated egt was about 850 F. The rear cylinders were consistently reporting the near 450 while the front cylinders were cooler. I imagine fuel distribution and cool air from the fan cause much of the variance.
So without adding another egt gauge near the head its hard to quantify the difference between the two probe locations.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: [GMCnet] New egt and tranny temp gauges [message #261318 is a reply to message #261317] |
Mon, 08 September 2014 18:21 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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I was afraid you'd get that sort of readings.
I have "identical" thermocouples on the two banks of the Cad500, both in
nearly symmetrical positions. That makes it really disturbing to see
consistently 100*-150*F difference between them. I haven't been able to
identify any reason for the variance, which is always in the same
direction. I guess I'm hoping the identical TC's aren't.
It will be interesting to see how the engine and TC readings fare on the
2500 mile trip to Chippewa Falls we're starting next week. I presume we'll
get to meet there?
Ken H.
On Mon, Sep 8, 2014 at 7:03 PM, jerrod winter wrote:
> I measured the outlet pipe surface temp very near the head with a fluke
> contact surface probe. The surface temp can tell you if you have a jug out
> of
> line but it doesn't indicate actual egt temp well. Surface temps were
> between 375 to 450 F while indicated egt was about 850 F. The rear
> cylinders
> were consistently reporting the near 450 while the front cylinders were
> cooler. I imagine fuel distribution and cool air from the fan cause much of
> the variance.
>
> So without adding another egt gauge near the head its hard to quantify
> the difference between the two probe locations.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: New egt and tranny temp gauges [message #261320 is a reply to message #261224] |
Mon, 08 September 2014 18:43 |
winter
Messages: 247
Registered: September 2007
Location: MPLS MN
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I would also expect the temp difference from gauge locations would change based on exhaust flow rate and engine load. An engine spun up to 2500 to 3000 rpm may be flowing enough exhaust to even out the temps. Slowing the flow down would tend to make them diverge. Seems like it would make sense but I don't have measurements to back it up.
Chippewa falls is about a 60 mile drive for us. We won't be getting there till Saturday morning though due to school and work. Although we've had the rig for over 10 years, this will be our first rally. Should be a good time.
Jerrod Winter
1977 Palm Beach
Green Jelly Bean
Twin Cities, Minnesota
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| Re: New egt and tranny temp gauges [message #261321 is a reply to message #261224] |
Mon, 08 September 2014 18:45 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
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I wonder if the throttle angle on the carb might affect fuel distribution, making the EGT hotter on the front cylinders....
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: New egt and tranny temp gauges [message #261359 is a reply to message #261224] |
Tue, 09 September 2014 01:31 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
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Ken,
I'd be tempted to swap the EGT sensors side to side and see if the same side stays hotter. Matt Colie would be worth talking to at Chippewa Falls, given all his lab time, but I don't think it takes a great deal of difference in mixture flow or jetting to get those kind of temperature differences. I don't know anything about Cadillacs, but in the 70's it was pretty common to "stagger jet" big block Chevy's to balance the cylinder temps/outputs.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: [GMCnet] New egt and tranny temp gauges [message #261364 is a reply to message #261359] |
Tue, 09 September 2014 06:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Craig,
Unfortunately, the way I routed the TC wires, it would be a major job to
swap the TC's themselves. Since those wires are sort of delicate, I really
hate to do that. What I do intend to do, on a upcoming 160 mile round trip
is to swap the injectors for the 80 mile return.
Thanks for the input; I hadn't heard about "stagger jetting". I'm sure
I'll be talking to Matt at CF.
Ken H.
On Tue, Sep 9, 2014 at 2:31 AM, Craig Lechowicz
wrote:
> Ken,
> I'd be tempted to swap the EGT sensors side to side and see if the same
> side stays hotter. Matt Colie would be worth talking to at Chippewa Falls,
> given all his lab time, but I don't think it takes a great deal of
> difference in mixture flow or jetting to get those kind of temperature
> differences.
> I don't know anything about Cadillacs, but in the 70's it was pretty
> common to "stagger jet" big block Chevy's to balance the cylinder
> temps/outputs.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] New egt and tranny temp gauges [message #261384 is a reply to message #261375] |
Tue, 09 September 2014 08:58 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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It'll probably hit me right after I hit [Enter], but right now I've no idea
what an EGO is! :-)
Ken H.
On Tue, Sep 9, 2014 at 9:17 AM, Matt Colie wrote:
> After decades of working K & J (even a few others) thermocouples, the
> likelihood of 100°F variation between couples is slim to non-existent. But,
> what you could be seeing is variation in the placement in the stream.
> That can make that much difference.
>
> Are you running dual EGOs? Most engines have that much variation bank to
> bank but it could ofter be seen in the EGO variation.
>
> Matt - still bring in electricity in 5 gallon cans.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] New egt and tranny temp gauges [message #261423 is a reply to message #261400] |
Tue, 09 September 2014 18:05 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Thanks, Matt, for the vocabulary expansion. :-)
In the military, we had a rule that every first mention must always be in
the form My Favorite Word (MFW). I try to stick to that, but sometimes
slip with well known terms; or reverse the order.
No, I run a single EGO, on the right bank. I do have a Wide Band (WB) HEGO
after the Y, but haven't yet tried using it for feedback.
You're probably right about the ThermoCouples (TC's) having similar
responses. Today I spent some time with the ignition on and engine mostly
off. The two channels tracked within a degree or two of ambient and
identically. When I did briefly run the engine, they began to disagree
right away, indicating to me that there IS some difference in the cylinders
or the TC placement, more likely the former than the latter.
Ken H.
On Tue, Sep 9, 2014 at 3:16 PM, Matt Colie wrote:
> Ken Henderson wrote on Tue, 09 September 2014 09:58
>> It'll probably hit me right after I hit [Enter], but right now I've no
> idea what an EGO is! :)
>>
>> Ken H.
>
> Sorry Ken,
>
> Exhaust Gas Oxygen (sensor)
> Sometimes they are HEGO
> Heated Exhaust Gas Oxygen (sensor)
>
> I try not to throw around TLA (Three Letter Abbreviations) with the
> translation close by..
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: New egt and tranny temp gauges [message #261439 is a reply to message #261224] |
Tue, 09 September 2014 19:44 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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Well, Thuh Cumpinny just sent me the new gee - Whiz fluke thermometer. It's a spot IR, but shows temps on the entire screen via color. I'm minded to schlep it home and run my coach up the freeway with the hatch open and see what the headers look like with it. It has a 'save' function, and somehow, I think it saves the screen. If it does, I'll post the pictures. As soon as I can find my pics on the photosite, last I looked it didn't see them.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: New egt and tranny temp gauges [message #261447 is a reply to message #261224] |
Tue, 09 September 2014 20:35 |
lotsofspareparts
Messages: 726
Registered: May 2014
Location: Arlington, WA
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I hate to bust in on a subject I know almost near nothing about but opening the hatch while driving is going to increase the airflow over the entire engine and exhaust exponentially, take the IR temp quickly.
My .02
Jared
Jared & Tina Lazaron + 14yr old Daughter.....
77 Eleganza II "Recherché".....
73 Canyon Lands 230 "Elephant"
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| Re: [GMCnet] New egt and tranny temp gauges [message #261551 is a reply to message #261447] |
Thu, 11 September 2014 00:38 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
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When I was driving The Blue Streak into Sydney the raised engine hatch popped open (the PO failed to install any kind of latches).
It stayed open for maybe ten seconds then closed.
The reason it did that is ram air increased the pressure in the interior and dropped when it got as high as it could and then the
flow dropped off and the engine hatch dropped.
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Jared
Sent: Tuesday, September 09, 2014 8:35 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] New egt and tranny temp gauges
I hate to bust in on a subject I know almost near nothing about but opening the hatch while driving is going to increase the airflow
over the entire engine and exhaust exponentially, take the IR temp quickly.
My .02
Jared
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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