GMC single muffler

C

claude brousson

New member
Jan 20, 1999
292
0
0
Gene-

Seeing that you have now converted to a single muffler, being the
careful man that you are, I presume you have already calculated into the
equation prior to the modification at least all of the following:
increased back pressure with only one muffler; reduced horse power on
hills; increased residual moisture and acid accumulation in muffler;
increased costs for more frequent muffler replacement; and increased gas
usage at the current high prices. Of course with the muffler at the back
you will naturally want to measure the number of degrees in lower
temperature it is running at so that will require temp. sensors on it
with a remote gauge up at the dash so you can note differences between
short trips versus long trips.

Just wondering, curious,and maybe thinking,

Claude
 
Claude,
What leads you to the conclusions that there is increased back
pressure/reduced horsepower.Considering stock vs. my single set up if
anything I have reduced back pressure and probably a bit more
horsepower.Acid and moisture in the muffler,don"t think so in my
case,shortest distance run would be 45 miles to Ockechobee.Haven"t found the
need to run to the store for milk.What has been reduced is underhood/engine
block temps,greatly reduced noise from same area,loudest noise now is tire
tread.Why I can even talk to my wife without hollerin,hey now that I think
about it maybe I'll change back.

Jim Penrod Jus hangin out an bein cool in Lake Placid, F.L.A.
 
Well we need a few more gauges than that,

temp reduced in the engine compartment
more even pressure with the immediate crossover
sound reduction in the engine compartment
reduced manifold temperature
etc, etc

Who the heck knows since we don't run these things on the Dynos' but if you
blow out one muffler and they want $370 to replace both it is a great time
to try one TURBO in the rear. Looks like a number of us are trying it, so
this could be a good chance to see if there are problems. Seems to be the
way the Corvettes are going so I figured maybe it will run like a Corvette.
;>)

gene

>Gene-
>
>Seeing that you have now converted to a single muffler, being the
>careful man that you are, I presume you have already calculated into the
>equation prior to the modification at least all of the following:
>increased back pressure with only one muffler; reduced horse power on
>hills; increased residual moisture and acid accumulation in muffler;
>increased costs for more frequent muffler replacement; and increased gas
>usage at the current high prices. Of course with the muffler at the back
>you will naturally want to measure the number of degrees in lower
>temperature it is running at so that will require temp. sensors on it
>with a remote gauge up at the dash so you can note differences between
>short trips versus long trips.
>
>Just wondering, curious,and maybe thinking,
>
>Claude
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
A little bird, who is closely related to me and who is an engineer for the
company that built the GMC (It shares the same first two initials) told me that
his company ran extensive tests on the larger exhaust pipes. At some point, the
increased size of the pipes results in turbulence, which negates some of the
advantages of the bigger pipes, especially over a long run like we have....bigger
is not necessarily better (This is also what I tell Julie!)

This study, interestingly enough, was done on Honda cars! They had suspected
this to be the case because Honda had not been increasing the size of the exhaust
pipes as much as the American builders. As to what size is correct for our
GMC's....That remains to be seen. Anyone have a spare Dyno I can borrow? Our
coach came with dual glasspacks (about 3-1/2 inches in diameter. I am listening
intently to see what others are doing so I don't wake the neighbors at 4:00 am
when I head to the Adirondacks to go fishing.

Ron and Julie
73 Painted Desert

> In a message dated 2/25/00 11:34:41 AM Mountain Standard Time,

>
>
> Seeing that you have now converted to a single muffler, being the
> careful man that you are, I presume you have already calculated into the
> equation prior to the modification at least all of the following:
> increased back pressure with only one muffler; reduced horse power on
> hills; increased residual moisture and acid accumulation in muffler;
> increased costs for more frequent muffler replacement; and increased gas
> usage at the current high prices. >>
>
> Claude - the calculations show that the use of a 3" tailpipe with a 3" inlet
> and outlet muffler would give almost 50% greater flow area than a 2-1/2"
> pipe. A factor of 9 versus 6.25. This should then give less back pressure
> instead of your statement that it would have increased back pressure. It
> would also probably increase horsepower on hills, and have less muffler
> surface area to allow condensation and acid accumulation. I also suspect
> that it would give improved gas mileage. I can't follow your reasoning. Any
> facts to support your assumptions?
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
Steve, Gene or if you gotta single muffler guys,
Did you notice any leaning of the carb when you did this? I have to have
an exhaust installed shortly and if I can convince the local shop here to do
the 3" with a single rear Dyno-Max muffler I will do it. I was also going to
add the Ragusa ram air and flex duct to my air cleaner.
I'm starting to wonder if I'll need to adj the carb because it may lean
things out a bit too much after all this? Any thoughts?

Nate '75GB (Good working on H-D weather... cloudy/drizzle/44 degrees)Omaha

>

Date: Fri, 25 Feb 2000 20:58:26 -0800
From: gene
Subject: Re: GMC: GMC single muffler

Well we need a few more gauges than that,

temp reduced in the engine compartment
more even pressure with the immediate crossover
sound reduction in the engine compartment
reduced manifold temperature
etc, etc

Who the heck knows since we don't run these things on the Dynos' but if you
blow out one muffler and they want $370 to replace both it is a great time
to try one TURBO in the rear. Looks like a number of us are trying it, so
this could be a good chance to see if there are problems. Seems to be the
way the Corvettes are going so I figured maybe it will run like a Corvette.
;>)

gene
 
I cannot tell about the mix since the computer of the TBI adjusts all the
time to keep the mixture correct.

I am not sure what is going on with the back pressure... Claude thinks it
might be going up ??

gene

>Steve, Gene or if you gotta single muffler guys,
> Did you notice any leaning of the carb when you did this? I have to have
>an exhaust installed shortly and if I can convince the local shop here to do
>the 3" with a single rear Dyno-Max muffler I will do it. I was also going to
>add the Ragusa ram air and flex duct to my air cleaner.
> I'm starting to wonder if I'll need to adj the carb because it may lean
>things out a bit too much after all this? Any thoughts?
>
>Nate '75GB (Good working on H-D weather... cloudy/drizzle/44 degrees)Omaha
>
>>
>
>Date: Fri, 25 Feb 2000 20:58:26 -0800
>From: gene
>Subject: Re: GMC: GMC single muffler
>
>Well we need a few more gauges than that,
>
>temp reduced in the engine compartment
>more even pressure with the immediate crossover
>sound reduction in the engine compartment
>reduced manifold temperature
>etc, etc
>
>Who the heck knows since we don't run these things on the Dynos' but if you
>blow out one muffler and they want $370 to replace both it is a great time
>to try one TURBO in the rear. Looks like a number of us are trying it, so
>this could be a good chance to see if there are problems. Seems to be the
>way the Corvettes are going so I figured maybe it will run like a Corvette.
>;>)
>
>gene
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
Gene,

One way to find out would be to do a before/after test with an exhaust back
pressure gauge (J.C Whitney's 81AN7662B, comes with oxygen sensor adapters
and other fittings).
Just a thought.

Peter
77 Eleganza II
Colorado

- ----- Original Message -----
From: "gene"
To:
Sent: Saturday, February 26, 2000 12:28 PM
Subject: Re: GMC: GMC single muffler

>
>
>
> I cannot tell about the mix since the computer of the TBI adjusts all the
> time to keep the mixture correct.
>
> I am not sure what is going on with the back pressure... Claude thinks it
> might be going up ??
>
> gene
>
>

> >Steve, Gene or if you gotta single muffler guys,
> > Did you notice any leaning of the carb when you did this? I have to
have
> >an exhaust installed shortly and if I can convince the local shop here to
do
> >the 3" with a single rear Dyno-Max muffler I will do it. I was also going
to
> >add the Ragusa ram air and flex duct to my air cleaner.
> > I'm starting to wonder if I'll need to adj the carb because it may lean
> >things out a bit too much after all this? Any thoughts?
> >
> >Nate '75GB (Good working on H-D weather... cloudy/drizzle/44
degrees)Omaha
> >
> >>
> >
> >Date: Fri, 25 Feb 2000 20:58:26 -0800
> >From: gene
> >Subject: Re: GMC: GMC single muffler
> >
> >Well we need a few more gauges than that,
> >
> >temp reduced in the engine compartment
> >more even pressure with the immediate crossover
> >sound reduction in the engine compartment
> >reduced manifold temperature
> >etc, etc
> >
> >Who the heck knows since we don't run these things on the Dynos' but if
you
> >blow out one muffler and they want $370 to replace both it is a great
time
> >to try one TURBO in the rear. Looks like a number of us are trying it,
so
> >this could be a good chance to see if there are problems. Seems to be
the
> >way the Corvettes are going so I figured maybe it will run like a
Corvette.
> >;>)
> >
> >gene
> >
> >
> Genef -- 77PB/ore/ca
> GMC MOTORHOME INFORMATION
> mr.erf
> http://www.california.com/~eagle/
>
 
Too late for me but mandatory for the next guy

gene

>Gene,
>
>One way to find out would be to do a before/after test with an exhaust back
>pressure gauge (J.C Whitney's 81AN7662B, comes with oxygen sensor adapters
>and other fittings).
>Just a thought.
>
>Peter
>77 Eleganza II
>Colorado
>
>
>----- Original Message -----
>From: "gene"
>To:
>Sent: Saturday, February 26, 2000 12:28 PM
>Subject: Re: GMC: GMC single muffler
>
>
>>
>>
>>
>> I cannot tell about the mix since the computer of the TBI adjusts all the
>> time to keep the mixture correct.
>>
>> I am not sure what is going on with the back pressure... Claude thinks it
>> might be going up ??
>>
>> gene
>>
>>

>> >Steve, Gene or if you gotta single muffler guys,
>> > Did you notice any leaning of the carb when you did this? I have to
>have
>> >an exhaust installed shortly and if I can convince the local shop here to
>do
>> >the 3" with a single rear Dyno-Max muffler I will do it. I was also going
>to
>> >add the Ragusa ram air and flex duct to my air cleaner.
>> > I'm starting to wonder if I'll need to adj the carb because it may lean
>> >things out a bit too much after all this? Any thoughts?
>> >
>> >Nate '75GB (Good working on H-D weather... cloudy/drizzle/44
>degrees)Omaha
>> >
>> >>
>> >
>> >Date: Fri, 25 Feb 2000 20:58:26 -0800
>> >From: gene
>> >Subject: Re: GMC: GMC single muffler
>> >
>> >Well we need a few more gauges than that,
>> >
>> >temp reduced in the engine compartment
>> >more even pressure with the immediate crossover
>> >sound reduction in the engine compartment
>> >reduced manifold temperature
>> >etc, etc
>> >
>> >Who the heck knows since we don't run these things on the Dynos' but if
>you
>> >blow out one muffler and they want $370 to replace both it is a great
>time
>> >to try one TURBO in the rear. Looks like a number of us are trying it,
>so
>> >this could be a good chance to see if there are problems. Seems to be
>the
>> >way the Corvettes are going so I figured maybe it will run like a
>Corvette.
>> >;>)
>> >
>> >gene
>> >
>> >
>> Genef -- 77PB/ore/ca
>> GMC MOTORHOME INFORMATION
>> mr.erf
>> http://www.california.com/~eagle/
>>
>
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
 
You must log in or register to reply here.
Get your shine on at www.cruzingear.co
Applied GMC

Share this page

Share this page
Top Bottom
Back