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Re: [GMCnet] 4.8 MPG. [message #324092] Wed, 20 September 2017 22:12 Go to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma: -62
Senior Member
Bob, watch the exhaust temp in just off of lean cruise. It gets into the
danger zone really fast. Talk to Randy and George before you do too much,
particularly with a heavily laden coach. It can be done, with careful
management.
Jim Hupy
Salem, Or.
78 GMC ROYALE 403

On Sep 20, 2017 7:02 PM, "Bob Dunahugh" wrote:

That's the MPG range I got too with the carb. Got about 7.5 mpg with a
17000 lbs GVW over 538 miles to Elkhart. Time will tell with more miles.
Extremely pleased with the Howell EFI. Next to add the EBL so I can read
instant MPGs, and go to the 16.5 fuel mixture in the lean burn mode. Bob
Dunahugh
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Re: [GMCnet] 4.8 MPG. [message #324095 is a reply to message #324092] Wed, 20 September 2017 23:51 Go to previous messageGo to next message
richshoop is currently offline  richshoop   United States
Messages: 190
Registered: April 2017
Karma: 0
Senior Member
Watching the exhaust gas temperature is fairly standard stuff for aircraft piston engines, lots of information available for that area of interest. Be VERY careful with the lean out, minute changes can dramatically change the engine operating characteristics, including exhaust valve damage, pre ignition due to higher operating temperatures, etc,

----- Original Message -----

From: "James Hupy"
To: "gmclist"
Sent: Wednesday, September 20, 2017 8:12:57 PM
Subject: Re: [GMCnet] 4.8 MPG.

Bob, watch the exhaust temp in just off of lean cruise. It gets into the
danger zone really fast. Talk to Randy and George before you do too much,
particularly with a heavily laden coach. It can be done, with careful
management.
Jim Hupy
Salem, Or.
78 GMC ROYALE 403

On Sep 20, 2017 7:02 PM, "Bob Dunahugh" wrote:

That's the MPG range I got too with the carb. Got about 7.5 mpg with a
17000 lbs GVW over 538 miles to Elkhart. Time will tell with more miles.
Extremely pleased with the Howell EFI. Next to add the EBL so I can read
instant MPGs, and go to the 16.5 fuel mixture in the lean burn mode. Bob
Dunahugh
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Re: [GMCnet] 4.8 MPG. [message #324103 is a reply to message #324095] Thu, 21 September 2017 08:55 Go to previous messageGo to next message
Keith V is currently offline  Keith V   United States
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
Senior Member
I've looked around for exhaust gas temperature info and didn't really find anything helpful.

any suggestions?

________________________________
From: Gmclist on behalf of richshoop@comcast.net
Sent: Wednesday, September 20, 2017 11:51:41 PM
To: gmclist
Subject: Re: [GMCnet] 4.8 MPG.

Watching the exhaust gas temperature is fairly standard stuff for aircraft piston engines, lots of information available for that area of interest. Be VERY careful with the lean out, minute changes can dramatically change the engine operating characteristics, including exhaust valve damage, pre ignition due to higher operating temperatures, etc,

----- Original Message -----

From: "James Hupy"
To: "gmclist"
Sent: Wednesday, September 20, 2017 8:12:57 PM
Subject: Re: [GMCnet] 4.8 MPG.

Bob, watch the exhaust temp in just off of lean cruise. It gets into the
danger zone really fast. Talk to Randy and George before you do too much,
particularly with a heavily laden coach. It can be done, with careful
management.
Jim Hupy
Salem, Or.
78 GMC ROYALE 403

On Sep 20, 2017 7:02 PM, "Bob Dunahugh" wrote:

That's the MPG range I got too with the carb. Got about 7.5 mpg with a
17000 lbs GVW over 538 miles to Elkhart. Time will tell with more miles.
Extremely pleased with the Howell EFI. Next to add the EBL so I can read
instant MPGs, and go to the 16.5 fuel mixture in the lean burn mode. Bob
Dunahugh
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Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
Re: [GMCnet] 4.8 MPG. [message #324104 is a reply to message #324103] Thu, 21 September 2017 09:18 Go to previous messageGo to next message
James Hupy is currently offline  James Hupy   United States
Messages: 6806
Registered: May 2010
Karma: -62
Senior Member
You can go a whole bunch of directions with egt. Full meal deal says probes
at each exhaust port, placement is critical. Or downstream a bit where
there is one stream per side, kinda like a O2 sensor or a cat converter.
The lab rats here, of which there are a few good ones, will quote you
chapter and verse on this process. In any case, it ain't always what it
seems. By the time a simple system senses a high temperature, significant
damage might have already happened. But a complex system requires
interpretation that also might use up too much time to react. Takes a well
programmed computer to keep up with modifying the injector pulse width or
length, as well as ratcheting back ignition timing soon enough. Randy Van
Winkle and George have had first hand experience with lean cruise. Listen
to what they say. They learned first hand about it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Sep 21, 2017 6:56 AM, "Keith V" wrote:

> I've looked around for exhaust gas temperature info and didn't really
> find anything helpful.
>
> any suggestions?
>
> ________________________________
> From: Gmclist on behalf of
> richshoop@comcast.net
> Sent: Wednesday, September 20, 2017 11:51:41 PM
> To: gmclist
> Subject: Re: [GMCnet] 4.8 MPG.
>
> Watching the exhaust gas temperature is fairly standard stuff for aircraft
> piston engines, lots of information available for that area of interest. Be
> VERY careful with the lean out, minute changes can dramatically change the
> engine operating characteristics, including exhaust valve damage, pre
> ignition due to higher operating temperatures, etc,
>
> ----- Original Message -----
>
> From: "James Hupy"
> To: "gmclist"
> Sent: Wednesday, September 20, 2017 8:12:57 PM
> Subject: Re: [GMCnet] 4.8 MPG.
>
> Bob, watch the exhaust temp in just off of lean cruise. It gets into the
> danger zone really fast. Talk to Randy and George before you do too much,
> particularly with a heavily laden coach. It can be done, with careful
> management.
> Jim Hupy
> Salem, Or.
> 78 GMC ROYALE 403
>
> On Sep 20, 2017 7:02 PM, "Bob Dunahugh" wrote:
>
> That's the MPG range I got too with the carb. Got about 7.5 mpg with a
> 17000 lbs GVW over 538 miles to Elkhart. Time will tell with more miles.
> Extremely pleased with the Howell EFI. Next to add the EBL so I can read
> instant MPGs, and go to the 16.5 fuel mixture in the lean burn mode. Bob
> Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
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Re: [GMCnet] 4.8 MPG. [message #324191 is a reply to message #324103] Fri, 22 September 2017 10:31 Go to previous messageGo to next message
richshoop is currently offline  richshoop   United States
Messages: 190
Registered: April 2017
Karma: 0
Senior Member
Go to the Chief Aircraft Supply website. Find something related to EGT (Exhaust Gas Temperature), pick a manufacturer's website and follow the links. It has been too long since my airplane days to remember which manufacturer that I had installed on our Cessna 172. I'll look around a little and see if I can do some leg work for you. Sorry about the circular route. I wanted to respond as quickly as possible to prevent one of my GMC 6 wheeler friends from frying a perfectly good engine by over leaning, very easy to do.

----- Original Message -----

From: "Keith V"
To: "gmclist"
Sent: Thursday, September 21, 2017 6:55:35 AM
Subject: Re: [GMCnet] 4.8 MPG.

I've looked around for exhaust gas temperature info and didn't really find anything helpful.

any suggestions?

________________________________
From: Gmclist on behalf of richshoop@comcast.net
Sent: Wednesday, September 20, 2017 11:51:41 PM
To: gmclist
Subject: Re: [GMCnet] 4.8 MPG.

Watching the exhaust gas temperature is fairly standard stuff for aircraft piston engines, lots of information available for that area of interest. Be VERY careful with the lean out, minute changes can dramatically change the engine operating characteristics, including exhaust valve damage, pre ignition due to higher operating temperatures, etc,

----- Original Message -----

From: "James Hupy"
To: "gmclist"
Sent: Wednesday, September 20, 2017 8:12:57 PM
Subject: Re: [GMCnet] 4.8 MPG.

Bob, watch the exhaust temp in just off of lean cruise. It gets into the
danger zone really fast. Talk to Randy and George before you do too much,
particularly with a heavily laden coach. It can be done, with careful
management.
Jim Hupy
Salem, Or.
78 GMC ROYALE 403

On Sep 20, 2017 7:02 PM, "Bob Dunahugh" wrote:

That's the MPG range I got too with the carb. Got about 7.5 mpg with a
17000 lbs GVW over 538 miles to Elkhart. Time will tell with more miles.
Extremely pleased with the Howell EFI. Next to add the EBL so I can read
instant MPGs, and go to the 16.5 fuel mixture in the lean burn mode. Bob
Dunahugh
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Re: [GMCnet] 4.8 MPG. [message #324203 is a reply to message #324191] Fri, 22 September 2017 12:11 Go to previous message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Here's a dual channel digital multimeter similar to the one I use to
display L & R bank EGT's:

http://www.auberins.com/index.php?main_page=product_info&cPath=5_21&products_id=357

Auber has a wide assortment of inexpensive thermocouples of 'most any
mounting type desired. I use type K's with clamp-on mounts -- drill one
hole in each exhaust pipe and clamp the thermocouple into it with the
provided "hose clamp". Could hardly be easier. I've used mine for
probably 5 years with no problems -- except that I'm amazed at how hot the
Cad500's EGT's run. The iron manifolds probably contribute to it -- 1300*F
at cruise is not unusual.

Ken H.


On Fri, Sep 22, 2017 at 11:31 AM, wrote:

> Go to the Chief Aircraft Supply website. Find something related to EGT
> (Exhaust Gas Temperature), pick a manufacturer's website and follow the
> links. It has been too long since my airplane days to remember which
> manufacturer that I had installed on our Cessna 172. I'll look around a
> little and see if I can do some leg work for you. Sorry about the circular
> route. I wanted to respond as quickly as possible to prevent one of my GMC
> 6 wheeler friends from frying a perfectly good engine by over leaning, very
> easy to do.
>
> ----- Original Message -----
>
> From: "Keith V"
> To: "gmclist"
> Sent: Thursday, September 21, 2017 6:55:35 AM
> Subject: Re: [GMCnet] 4.8 MPG.
>
> I've looked around for exhaust gas temperature info and didn't really find
> anything helpful.
>
> any suggestions?
>
> ________________________________
> From: Gmclist on behalf of
> richshoop@comcast.net
> Sent: Wednesday, September 20, 2017 11:51:41 PM
> To: gmclist
> Subject: Re: [GMCnet] 4.8 MPG.
>
> Watching the exhaust gas temperature is fairly standard stuff for aircraft
> piston engines, lots of information available for that area of interest. Be
> VERY careful with the lean out, minute changes can dramatically change the
> engine operating characteristics, including exhaust valve damage, pre
> ignition due to higher operating temperatures, etc,
>
> ----- Original Message -----
>
> From: "James Hupy"
> To: "gmclist"
> Sent: Wednesday, September 20, 2017 8:12:57 PM
> Subject: Re: [GMCnet] 4.8 MPG.
>
> Bob, watch the exhaust temp in just off of lean cruise. It gets into the
> danger zone really fast. Talk to Randy and George before you do too much,
> particularly with a heavily laden coach. It can be done, with careful
> management.
> Jim Hupy
> Salem, Or.
> 78 GMC ROYALE 403
>
> On Sep 20, 2017 7:02 PM, "Bob Dunahugh" wrote:
>
> That's the MPG range I got too with the carb. Got about 7.5 mpg with a
> 17000 lbs GVW over 538 miles to Elkhart. Time will tell with more miles.
> Extremely pleased with the Howell EFI. Next to add the EBL so I can read
> instant MPGs, and go to the 16.5 fuel mixture in the lean burn mode. Bob
> Dunahugh
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
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>
> _______________________________________________
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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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