Mufflers??

[gilbert r. bethel]

I have ordered headers from HPC in Salt Lake City and upon inspecting the
mufflers they look like they are getting thin on the outside. I think I may
have to replace them soon. What mufflers should I run with the ceramic
coated headers. I would like to keep the noise to a minimum.

Russ Bethel
1976 Glenbrook

 

[rich and dottie major]

Russ, you want a free flowing exhaust system. I just installed Flowmasters on
mine and there was a noticable increase in performance. It's not noisy at all.

Rich Major
'78 Kingsley

> I have ordered headers from HPC in Salt Lake City and upon inspecting the
> mufflers they look like they are getting thin on the outside. I think I may
> have to replace them soon. What mufflers should I run with the ceramic
> coated headers. I would like to keep the noise to a minimum.
>
> Russ Bethel
> 1976 Glenbrook

 

[gilbert r. bethel]

Where do you find the Flowmasters?
- -----Original Message-----
From: Rich and Dottie Major
To: gmcmotorhome
Date: Monday, April 20, 1998 10:04 PM
Subject: Re: GMC: Mufflers??

>Russ, you want a free flowing exhaust system. I just installed
Flowmasters on
>mine and there was a noticable increase in performance. It's not noisy at
all.
>
>Rich Major
>'78 Kingsley
>

>
>> I have ordered headers from HPC in Salt Lake City and upon inspecting the
>> mufflers they look like they are getting thin on the outside. I think I
may
>> have to replace them soon. What mufflers should I run with the ceramic
>> coated headers. I would like to keep the noise to a minimum.
>>
>> Russ Bethel
>> 1976 Glenbrook
>
>
>
>

 

[marcus mcgee]

Try Summit or Jeggs

Summit has a Net store or you can get the catalog. Also Jardine has a
good muffler if you are looking to go to the 3" pipes.

Marcus

>
> Where do you find the Flowmasters?
> -----Original Message-----
> From: Rich and Dottie Major
> To: gmcmotorhome
> Date: Monday, April 20, 1998 10:04 PM
> Subject: Re: GMC: Mufflers??
>
> >Russ, you want a free flowing exhaust system. I just installed
> Flowmasters on
> >mine and there was a noticable increase in performance. It's not noisy at
> all.
> >
> >Rich Major
> >'78 Kingsley
> >

> >
> >> I have ordered headers from HPC in Salt Lake City and upon inspecting the
> >> mufflers they look like they are getting thin on the outside. I think I
> may
> >> have to replace them soon. What mufflers should I run with the ceramic
> >> coated headers. I would like to keep the noise to a minimum.
> >>
> >> Russ Bethel
> >> 1976 Glenbrook
> >
> >
> >
> >

 

[zachary zehnacker]

>Russ, you want a free flowing exhaust system. I just installed
Flowmasters on
>mine and there was a noticable increase in performance. It's not noisy at
all.
>
>Rich Major
>'78 Kingsley

I'm not sure I can agree with this recommendation. The Flowmaster
mufflers we got for replacing the Dynomax ones that came with our 3"
Jardine exhaust system were VERY loud. Flowmaster uses noise cancellation
and has no packing material whatsoever. The back of the motorhome was
unusable while traveling the exhaust was so loud and pulsating. They are
built like tanks, however, and would probably outlast your motorhome.
Unfortunately for us, we ended up taking them off to put Dynomax mufflers
back on. The Dynomax mufflers are only loud in one RPM range instead of
the entire range like the Flowmasters were. The Dynomax mufflers are built
pretty cheaply, however, and do not last much over a few years. The next
time we do it, we will probably look to some stock type mufflers which are
not free flow at all. At the RPM's we turn our motor (usually less than
3500 RPM) and with two mufflers, we just don't think the better flow is
worth the noise it creates. I have seen ads for a new muffler from Walker
(same company as Dynomax) that is supposed to be a little more free flowing
than stock, but not as free flowing as their Dynomax brand mufflers. These
might be a better compromise for flow and noise.

Just our experiences,
Zak

PS - All our travel is done while towing a trailer, so our noise
experiences might be different from others. Our motor is under a much
heavier load at all times which might account for our Flowmaster/Dynomax
experience. The motorhome, however, was silent (inside) when it still had
the stock exhaust system even when we were towing.

 

[rich and dottie major]

Zachary/Russ

When I had the Flowmasters installed I was looking to increase the preformance
from the 403 CID motor. I must admit that no one travel in the rear of our
motorhome while I am driving so we can not comment on noise back there.
However, there is no noticable noise from the exhaust system while seated in
the front of the coach. In addition, Flowmaster has 3 types of mufflers with
different sound levels for various applications. I made sure I purchased the
most quiet muffler they had. I do use a louder Flowmaster on my 31 Ford, but
that was intentional and it is loud.

Flowmasters can be purchased from Summit Racing in Ohio, Tel 1-800-230-3030.
Summit is very large mail order supplier of automotive performance parts. And
they have the best prices. You can also call Flowmaster at 1-707-569-9929 and
discuss your application and they will recommend the correct part number.

Rich Major
'78 Kingsley

> >Russ, you want a free flowing exhaust system. I just installed
> Flowmasters on
> >mine and there was a noticable increase in performance. It's not noisy at
> all.
> >
> >Rich Major
> >'78 Kingsley
>
> I'm not sure I can agree with this recommendation. The Flowmaster
> mufflers we got for replacing the Dynomax ones that came with our 3"
> Jardine exhaust system were VERY loud. Flowmaster uses noise cancellation
> and has no packing material whatsoever. The back of the motorhome was
> unusable while traveling the exhaust was so loud and pulsating. They are
> built like tanks, however, and would probably outlast your motorhome.
> Unfortunately for us, we ended up taking them off to put Dynomax mufflers
> back on. The Dynomax mufflers are only loud in one RPM range instead of
> the entire range like the Flowmasters were. The Dynomax mufflers are built
> pretty cheaply, however, and do not last much over a few years. The next
> time we do it, we will probably look to some stock type mufflers which are
> not free flow at all. At the RPM's we turn our motor (usually less than
> 3500 RPM) and with two mufflers, we just don't think the better flow is
> worth the noise it creates. I have seen ads for a new muffler from Walker
> (same company as Dynomax) that is supposed to be a little more free flowing
> than stock, but not as free flowing as their Dynomax brand mufflers. These
> might be a better compromise for flow and noise.
>
> Just our experiences,
> Zak
>
> PS - All our travel is done while towing a trailer, so our noise
> experiences might be different from others. Our motor is under a much
> heavier load at all times which might account for our Flowmaster/Dynomax
> experience. The motorhome, however, was silent (inside) when it still had
> the stock exhaust system even when we were towing.

 

[bartz paul]

Russ:

I have approximately 10,000 miles experience since installing my exhaust
system (i. e. Thorley headers and Flowmaster mufflers) and don't
consider them loud. Yes, they have a low frequency sound/are louder up
to 40-45 mph, than the stock system I replaced, but not objectionable at
all. The performance increase is well worth it.

There is no noticeable difference in noise while riding in the rear of
the coach.

I used Flowmaster's 50 series/three chamber mufflers, P/N 52553 (cost
$125 ea where I bought) and also installed Flowmaster's heat shield
above them for added heat protection to the floor. They have a smaller
on, P/N 42553 (costs $53 ea), that several coach owners I know used.

Check with local auto performance shops in your area for Flowmaster
products. You will also want to get Flowmaster's Y collector pipe, P/N
Y250300A for your system.

Paul Bartz

> From: Gilbert R. Bethel [SMTP:rbethel]
> Sent: Monday, April 20, 1998 11:52 PM
> Subject: Re: GMC: Mufflers??
>
> Where do you find the Flowmasters?
> -----Original Message-----
> From: Rich and Dottie Major
> To: gmcmotorhome
> Date: Monday, April 20, 1998 10:04 PM
> Subject: Re: GMC: Mufflers??
>
>
> >Russ, you want a free flowing exhaust system. I just installed
> Flowmasters on
> >mine and there was a noticable increase in performance. It's not
> noisy at
> all.
> >
> >Rich Major
> >'78 Kingsley
> >

> >
> >> I have ordered headers from HPC in Salt Lake City and upon
> inspecting the
> >> mufflers they look like they are getting thin on the outside. I
> think I
> may
> >> have to replace them soon. What mufflers should I run with the
> ceramic
> >> coated headers. I would like to keep the noise to a minimum.
> >>
> >> Russ Bethel
> >> 1976 Glenbrook
> >
> >
> >
> >

 

[bartz paul]

Zak:

Just curious what part number Flowmaster muffler you used that cause
them to be objectionable?

One of the reasons I chose Flowmaster mufflers is because they say their
design creates a negative pressure in the muffler, and claim that
because of the pressure differential that heat is pulled from the engine
quicker.

Paul Bartz
> From: Zachary Zehnacker [SMTP:zakz]
> Sent: Tuesday, April 21, 1998 8:50 AM
> Subject: Re: GMC: Mufflers??
>

>
> Russ, you want a free flowing exhaust system. I just installed
> Flowmasters on mine and there was a noticable increase in performance.
> It's not noisy at all.
>
> Rich Major
> '78 Kingsley
>
> I'm not sure I can agree with this recommendation. The Flowmaster
> mufflers we got for replacing the Dynomax ones that came with our 3"
> Jardine exhaust system were VERY loud. Flowmaster uses noise
> cancellation and has no packing material whatsoever. The back of the
> motorhome was unusable while traveling the exhaust was so loud and
> pulsating. They are built like tanks, however, and would probably
> outlast your motorhome.
>
> Unfortunately for us, we ended up taking them off to put Dynomax
> mufflers back on. The Dynomax mufflers are only loud in one RPM range
> instead of the entire range like the Flowmasters were. The Dynomax
> mufflers are built pretty cheaply, however, and do not last much over
> a few years. The next time we do it, we will probably look to some
> stock type mufflers which are not free flow at all. At the RPM's we
> turn our motor (usually less than 3500 RPM) and with two mufflers, we
> just don't think the better flow is worth the noise it creates. I
> have seen ads for a new muffler from Walker (same company as Dynomax)
> that is supposed to be a little more free flowing
> than stock, but not as free flowing as their Dynomax brand mufflers.
> These might be a better compromise for flow and noise.
>
> Just our experiences,
> Zak
>
> PS - All our travel is done while towing a trailer, so our noise
> experiences might be different from others. Our motor is under a much
> heavier load at all times which might account for our
> Flowmaster/Dynomax experience. The motorhome, however, was silent
> (inside) when it still had the stock exhaust system even when we were
> towing.

 

[patrick flowers]

From: "Zachary Zehnacker"
To:
Subject: Re: GMC: Mufflers??
Date: Wed, 22 Apr 1998 17:18:55 -0700

> Zak:
>
> Just curious what part number Flowmaster muffler you used that cause
> them to be objectionable?
>

Paul,
I am not sure what the muffler part number was. I will look it up when
I get home and get a chance. They were supposed to be quiet ones according
to the Jeg's catalog, but I think when we actually looked up the part
number they might not have been. They were the only ones we saw advertised
that were the right size and had the same inlet/outlet configuration as the
Dynomax mufflers that came with our Jardine 3" system.

> One of the reasons I chose Flowmaster mufflers is because they say their
> design creates a negative pressure in the muffler, and claim that
> because of the pressure differential that heat is pulled from the engine
> quicker.
>
> Paul Bartz

I find a lot of their claims to be a little far fetched. They show
pictures in their ads that show the air going right through but the sound
getting trapped. I don't see how the sound is getting trapped if the air
is not or is not at least getting restricted by bouncing into the walls.
One other thing to note is that some back pressure can actually be a good
thing for low end torque which could be important for a motorhome.

We have never seen a car with Flowmasters that we considered to be
quiet. It is possible, however, that we have never seen a car with the
Flowmasters made to be as quiet as possible. Many were street/strip cars
which probably had the louder Flowmasters on. We have also experienced
this with the race cars that we have seen. Both our race cars have Borla
mufflers on them which you can see totally unobstructed right through.
These mufflers make a huge difference in the sound levels and have actually
seemed to help the power of the cars (we needed to put bigger jets and
squirters in the carbs of both cars). At a recent race, our car (and
others with Borlas) were consistently 3 dB quieter than cars that had
Flowmaster collector mufflers which actually look restrictive if try to
look through them.

One thing Flowmasters definately have going for them is durability,
however. These mufflers are built like tanks. They would probably outlast
any vehicle they are put on. We are not happy with the quality of the
Dynomax mufflers and are looking for something that will last longer and
still quiet it down to an acceptable level. We are looking into the new
Edelbrock stainless steel mufflers and the street Borla mufflers. We are
also looking into just going back to a stock type muffler.

Zak

PS- Which Flowmaster part number did you use and what is the inlet/outlet
configuration for it?