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[GMCnet] Exhaust Exit Question [message #94891] Fri, 06 August 2010 21:20 Go to next message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
Good Evening

I'm wrapping up my new exhaust system. Installed 2 new 2 1/2" Dynomax Turbo
Flow mufflers up front after the headers that feed into a Y, then 3" exhaust
from the Y back.

I've noticed that most exhausts exit to the side at the rear passenger side. As
I was installing the new 3" line through the frame it looked like it would work
great just sticking straight out the back.


So is it best to put in a 90 and exit the side or let it stick straight out the
back ?????? Since I see most of them out the side, what am I missing here ??
Other than blowing the exhaust right onto what you tow or ????

Thanks

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
Re: [GMCnet] Exhaust Exit Question [message #94897 is a reply to message #94891] Fri, 06 August 2010 21:46 Go to previous messageGo to next message
pete lyons is currently offline  pete lyons   United States
Messages: 81
Registered: June 2010
Karma: 0
Member
Ray,

For what it's worth, I just finished mine and ran it straight out the back.

When I was getting estimates, the shops cautioned against the right angle
because of the proximity of the window.

I also figured that I could always go back and cut the pipe and put a 90 on if I wanted to take it out the side.

Pete Lyons
New Albany IN
76 eleganza ii

Sent from my iPhone

On Aug 6, 2010, at 10:20 PM, Ray Erspamer <78gmc-royale@att.net> wrote:

> Good Evening
>
> I'm wrapping up my new exhaust system. Installed 2 new 2 1/2" Dynomax Turbo
> Flow mufflers up front after the headers that feed into a Y, then 3" exhaust
> from the Y back.
>
> I've noticed that most exhausts exit to the side at the rear passenger side. As
> I was installing the new 3" line through the frame it looked like it would work
> great just sticking straight out the back.
>
>
> So is it best to put in a 90 and exit the side or let it stick straight out the
> back ?????? Since I see most of them out the side, what am I missing here ??
> Other than blowing the exhaust right onto what you tow or ????
>
> Thanks
>
> Ray
>
>
> Ray & Lisa Erspamer
> 78 Royale Center Kitchen
> TZE368V101144
> Wauwatosa, Wisconsin 53226
> Email: 78GMC-Royale@att.net
> 414-745-3188
> Web Site: http://ray-lisa.page.tl/
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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Re: [GMCnet] Exhaust Exit Question [message #94899 is a reply to message #94897] Fri, 06 August 2010 21:57 Go to previous messageGo to next message
Kosier is currently offline  Kosier   United States
Messages: 834
Registered: February 2008
Karma: 1
Senior Member
Just remember that if you back up and run that straight pipe into
something,
the force will be transferred into that expensive Y-pipe up
front.
Or, if you cross a dip going into a gas station and mash the
tailpipe against
the bumper, it won't be able to relieve it's flatulence. LOL

Gary Kosier

Subject: Re: [GMCnet] Exhaust Exit Question


> Ray,
>
> For what it's worth, I just finished mine and ran it straight
> out the back.
>
> When I was getting estimates, the shops cautioned against the
> right angle
> because of the proximity of the window.
>
> I also figured that I could always go back and cut the pipe and
> put a 90 on if I wanted to take it out the side.
>
> Pete Lyons
> New Albany IN
> 76 eleganza ii
>
> Sent from my iPhone
>
> On Aug 6, 2010, at 10:20 PM, Ray Erspamer
> <78gmc-royale@att.net> wrote:
>
>> Good Evening
>>
>> I'm wrapping up my new exhaust system. Installed 2 new 2 1/2"
>> Dynomax Turbo
>> Flow mufflers up front after the headers that feed into a Y,
>> then 3" exhaust
>> from the Y back.
>>
>> I've noticed that most exhausts exit to the side at the rear
>> passenger side. As
>> I was installing the new 3" line through the frame it looked
>> like it would work
>> great just sticking straight out the back.
>>
>>
>> So is it best to put in a 90 and exit the side or let it stick
>> straight out the
>> back ?????? Since I see most of them out the side, what am I
>> missing here ??
>> Other than blowing the exhaust right onto what you tow or ????
>>
>> Thanks
>>
>> Ray
>>
>>
>> Ray & Lisa Erspamer
>> 78 Royale Center Kitchen
>> TZE368V101144
>> Wauwatosa, Wisconsin 53226
>> Email: 78GMC-Royale@att.net
>> 414-745-3188
>> Web Site: http://ray-lisa.page.tl/
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

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Re: [GMCnet] Exhaust Exit Question [message #94900 is a reply to message #94891] Fri, 06 August 2010 22:00 Go to previous messageGo to next message
Bob de Kruyff   United States
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
Senior Member
""So is it best to put in a 90 and exit the side or let it stick straight out the
back ?????? Since I see most of them out the side, what am I missing here ??
Other than blowing the exhaust right onto what you tow or ????

Thanks

Ray
"" Ray, I think at this point it really dosn't matter. It's one of convenience or appearance!


Bob de Kruyff
78 Eleganza
Chandler, AZ
Re: [GMCnet] Exhaust Exit Question [message #94906 is a reply to message #94891] Fri, 06 August 2010 23:10 Go to previous messageGo to next message
zhagrieb is currently offline  zhagrieb   United States
Messages: 676
Registered: August 2009
Location: Portland Oregon
Karma: 0
Senior Member
Easily crushed.

Glenn


Glenn Giere, Portland OR, K7GAG '73 "Moby the Motorhome" 26'
Re: [GMCnet] Exhaust Exit Question [message #94908 is a reply to message #94891] Fri, 06 August 2010 23:39 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
Your taking a simple but not a very good way.
The pipe need to start to raise up to keep from dragging in the back.
The most expensive part on our kit is the Tail pipe as it has 4 bends in tit
to work and fit properly. All are Mandrel bent so there is no kinks.
You'll see what I'm saying when you do it your way like lot of others.

On Fri, Aug 6, 2010 at 7:20 PM, Ray Erspamer <78gmc-royale@att.net> wrote:

> Good Evening
>
> I'm wrapping up my new exhaust system. Installed 2 new 2 1/2" Dynomax
> Turbo
> Flow mufflers up front after the headers that feed into a Y, then 3"
> exhaust
> from the Y back.
>
> I've noticed that most exhausts exit to the side at the rear passenger
> side. As
> I was installing the new 3" line through the frame it looked like it would
> work
> great just sticking straight out the back.
>
>
> So is it best to put in a 90 and exit the side or let it stick straight out
> the
> back ?????? Since I see most of them out the side, what am I missing here
> ??
> Other than blowing the exhaust right onto what you tow or ????
>
> Thanks
>
> Ray
>
>
> Ray & Lisa Erspamer
> 78 Royale Center Kitchen
> TZE368V101144
> Wauwatosa, Wisconsin 53226
> Email: 78GMC-Royale@att.net
> 414-745-3188
> Web Site: http://ray-lisa.page.tl/
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>



--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: [GMCnet] Exhaust Exit Question [message #94924 is a reply to message #94891] Sat, 07 August 2010 08:48 Go to previous messageGo to next message
bryant374 is currently offline  bryant374   United States
Messages: 563
Registered: May 2004
Location: Pleasant Valley, NY 12569
Karma: 1
Senior Member
>
>
> So is it best to put in a 90 and exit the side or let it stick straight out
> the
> back ?????? Since I see most of them out the side, what am I missing here
> ??
> Other than blowing the exhaust right onto what you tow or ????
>
> Thanks
>
> Ray
>
>

I didn't like the idea of another 90 deg. bend in the run and didn't want straight back since I towed. The 45 deg. bend has worked well for the past 12 years. Taper the end cut and it will minimize the likelyhood of drag.


Bill Bryant
PO 1976~PB (owned 34 years)
1914 Ford (owned 70 years)
1965 Corvette (owned 39 years)
GMC Motorhome History
Re: [GMCnet] Exhaust Exit Question [message #94964 is a reply to message #94906] Sat, 07 August 2010 18:06 Go to previous messageGo to next message
Steven Ferguson is currently offline  Steven Ferguson   United States
Messages: 3447
Registered: May 2006
Karma: 0
Senior Member
I'm with Glenn on this one. Every rear exit exhaust pipe I've seen on
a GMC is smashed. Better to side exit. Anything below that bumper is
gonna drag at some point in a trip.

On Fri, Aug 6, 2010 at 9:10 PM, Glenn Giere <glenngiere@gmail.com> wrote:
>
>
> Easily crushed.
>
> Glenn
> _______________________________________________
> GMCnet mailing list
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>



--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Exhaust Exit Question [message #94969 is a reply to message #94964] Sat, 07 August 2010 18:32 Go to previous messageGo to next message
hal kading is currently offline  hal kading   United States
Messages: 642
Registered: February 2004
Location: Las Cruces NM
Karma: 4
Senior Member
I have a straight out 3" exhaust with no problems in 50K miles. The outlet is protected with a pair of swivel casters welded to the frame about 24" in front of the bumper. Keeps the hitch from dragging too.

Hal Kading 77 Kingsley 455 Las Cruces NM
Re: [GMCnet] Exhaust Exit Question [message #94975 is a reply to message #94924] Sat, 07 August 2010 20:35 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Bill,

I've got to take Double Trouble to a muffler shop on Monday to have a new
tailpipe made.

The one on it was NOT mandrel bent and "someone" backed into something and
bent it beyond 90°! The result was an oval about 1" by 2.5"! Gee I wonder if
that effected hi rpm operation? ;-)

Would you happen to have any pictures of your exhaust?

Regards,
Rob M.
USAussie

-----Original Message-----
From: Bill Bryant

I didn't like the idea of another 90 deg. bend in the run and didn't want
straight back since I towed. The 45 deg. bend has worked well for the past
12 years. Taper the end cut and it will minimize the likelyhood of drag.
--
Bill Bryant


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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
Re: [GMCnet] Exhaust Exit Question [message #94976 is a reply to message #94964] Sat, 07 August 2010 20:35 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Steve,

Here's one that's not smashed! ;-)

http://www.gmcmhphotos.com/photos/showphoto.php?photo=35267

This may look silly but IIRC if you put a 90° bend in a pipe it's like
adding seven feet of straight pipe vis-à-vis pressure drop.

Regards,
Rob M.
USAussie

-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Steven Ferguson
Sent: Saturday, August 07, 2010 7:07 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Exhaust Exit Question

I'm with Glenn on this one. Every rear exit exhaust pipe I've seen on
a GMC is smashed. Better to side exit. Anything below that bumper is
gonna drag at some point in a trip.

--
Steve Ferguson


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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
Re: [GMCnet] Exhaust Exit Question [message #94983 is a reply to message #94976] Sat, 07 August 2010 21:34 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
Robert Mueller wrote on Sat, 07 August 2010 20:35


IIRC if you put a 90° bend in a pipe it's like
adding seven feet of straight pipe vis-à-vis pressure drop.



There is no way that is even remotely true.
Well maybe on a high pressure fluid flow or something, but not on an already over sized exhaust pipe.

I ran a straight 90 out the back. I'm pretty sure the bumper will drag before it hits.

Jim K has a nice tailpipe in his kit, but I enjoy doing things myself and I think my plain jane 90 will be darn good


Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
Re: [GMCnet] Exhaust Exit Question [message #94988 is a reply to message #94983] Sat, 07 August 2010 22:03 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
The floor angles up and the pipe should also bend up about 15degrees then it
can do the 50-90 degree turn.
Most of the 90 degree bends that muffler shops do are very restrictive.


>



--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: [GMCnet] Exhaust Exit Question [message #94996 is a reply to message #94983] Sat, 07 August 2010 23:01 Go to previous messageGo to next message
USAussie is currently offline  USAussie   United States
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
Senior Member
Keith,

I worked as an engineer / field service rep for Hamilton Standard.

When we worked with the Xian Aircraft Company in China re-designing the air
conditioning ducting in their Y-7 aircraft there were all kinds of 90° bends
in the ducting they had in that aircraft. In fact the bend in the engine
bleed air ducting at the juncture of the wing and fuselage was greater than
90°!

We told them the same thing and they didn't believe us either so we
instrumented a duct with a 90° bend with pressure pickups and demonstrated
the effect of the bend vis-à-vis the pressure drop.

Unfortunately it was over 10 years ago and I don't remember the specific
flow rates and pressure drops.

Regards,
Rob M.
USAussie

-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Keith V
Sent: Saturday, August 07, 2010 10:34 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Exhaust Exit Question



Robert Mueller wrote on Sat, 07 August 2010 20:35
> IIRC if you put a 90° bend in a pipe it's like
> adding seven feet of straight pipe vis-à-vis pressure drop.


There is no way that is even remotely true.
Well maybe on a high pressure fluid flow or something, but not on an already
over sized exhaust pipe.

I ran a straight 90 out the back. I'm pretty sure the bumper will drag
before it hits.

Jim K has a nice tailpipe in his kit, but I enjoy doing things myself and I
think my plain jane 90 will be darn good
--
Keith
69 Vette
29 Dodge
75 Royale GMC
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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
Re: [GMCnet] Exhaust Exit Question [message #95004 is a reply to message #94891] Sun, 08 August 2010 00:25 Go to previous messageGo to next message
rallymaster is currently offline  rallymaster   United States
Messages: 662
Registered: February 2004
Location: North Plains, ORYGUN
Karma: -4
Senior Member
Keith, is that why all our GMC motorhome dash AC & heaters work so well
without any changes?

RonC


On Sat, 07 Aug 2010 21:34:00 -0500 Keith V <my427v8@hotmail.com> writes:
>
>
> Robert Mueller wrote on Sat, 07 August 2010 20:35
> > IIRC if you put a 90° bend in a pipe it's like
> > adding seven feet of straight pipe vis-à-vis pressure drop.
>
>
> There is no way that is even remotely true.
> Well maybe on a high pressure fluid flow or something, but not on an
> already over sized exhaust pipe.
>
> I ran a straight 90 out the back. I'm pretty sure the bumper will
> drag before it hits.
>
> Jim K has a nice tailpipe in his kit, but I enjoy doing things
> myself and I think my plain jane 90 will be darn good
> --
> Keith
> 69 Vette
> 29 Dodge
> 75 Royale GMC
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>


Ron & Linda Clark
1978 Eleganza II
North Plains, ORYGUN
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Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II
Re: [GMCnet] Exhaust Exit Question [message #95011 is a reply to message #94996] Sun, 08 August 2010 07:11 Go to previous messageGo to next message
Steven Ferguson is currently offline  Steven Ferguson   United States
Messages: 3447
Registered: May 2006
Karma: 0
Senior Member
Rob,
After traveling 20+ feet from the engine, I don't think the exhaust
having to make a 90 deg to exit has so much as an iota of effect on
efficiency. If you can detect the loss of performance from this, the
seat of your pants is a lot thinner than mine.

On Sat, Aug 7, 2010 at 9:01 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
> Keith,
>
> I worked as an engineer / field service rep for Hamilton Standard.
>
> When we worked with the Xian Aircraft Company in China re-designing the air
> conditioning ducting in their Y-7 aircraft there were all kinds of 90° bends
> in the ducting they had in that aircraft. In fact the bend in the engine
> bleed air ducting at the juncture of the wing and fuselage was greater than
> 90°!
>
> We told them the same thing and they didn't believe us either so we
> instrumented a duct with a 90° bend with pressure pickups and demonstrated
> the effect of the bend vis-à-vis the pressure drop.
>
> Unfortunately it was over 10 years ago and I don't remember the specific
> flow rates and pressure drops.
>
> Regards,
> Rob M.
> USAussie
>
> -----Original Message-----
> From: gmclist-bounces@temp.gmcnet.org
> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Keith V
> Sent: Saturday, August 07, 2010 10:34 PM
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Exhaust Exit Question
>
>
>
> Robert Mueller wrote on Sat, 07 August 2010 20:35
>> IIRC if you put a 90° bend in a pipe it's like
>> adding seven feet of straight pipe vis-à-vis pressure drop.
>
>
> There is no way that is even remotely true.
> Well maybe on a high pressure fluid flow or something, but not on an already
> over sized exhaust pipe.
>
> I ran a straight 90 out the back. I'm pretty sure the bumper will drag
> before it hits.
>
> Jim K has a nice tailpipe in his kit, but I enjoy doing things myself and I
> think my plain jane 90 will be darn good
> --
> Keith
> 69 Vette
> 29 Dodge
> 75 Royale GMC
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>



--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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Re: [GMCnet] Exhaust Exit Question [message #95012 is a reply to message #94975] Sun, 08 August 2010 07:55 Go to previous messageGo to next message
bryant374 is currently offline  bryant374   United States
Messages: 563
Registered: May 2004
Location: Pleasant Valley, NY 12569
Karma: 1
Senior Member
Re: [GMCnet] Exhaust Exit Question Sat, 07 August 2010 21:35
Robert Mueller

Bill,

I've got to take Double Trouble to a muffler shop on Monday to have a new
tailpipe made.

The one on it was NOT mandrel bent and "someone" backed into something and
bent it beyond 90°! The result was an oval about 1" by 2.5"! Gee I wonder if
that effected hi rpm operation? Wink

Would you happen to have any pictures of your exhaust?

Regards,
Rob M.
USAussie


Rob,
Sorry, I don't have pictures of my exhaust. Maybe I should explain that I still have a 2.5" pipes w/front mufflers. When the present system gets bad enough to replace, it will probably be with 3". I believe there is little justification to go to 3" until the old system requires replacement.


Bill Bryant
PO 1976~PB (owned 34 years)
1914 Ford (owned 70 years)
1965 Corvette (owned 39 years)
GMC Motorhome History
Re: [GMCnet] Exhaust Exit Question [message #95014 is a reply to message #95011] Sun, 08 August 2010 07:50 Go to previous messageGo to next message
pete lyons is currently offline  pete lyons   United States
Messages: 81
Registered: June 2010
Karma: 0
Member
I have always been told it was a gmc tradition that men wear speedo's when driving the coach.

Pete Lyons
New Albany in
76 eleganza ii

Sent from my iPhone

On Aug 8, 2010, at 7:11 AM, Steven Ferguson <botiemad11@gmail.com> wrote:

> Rob,
> After traveling 20+ feet from the engine, I don't think the exhaust
> having to make a 90 deg to exit has so much as an iota of effect on
> efficiency. If you can detect the loss of performance from this, the
> seat of your pants is a lot thinner than mine.
>
> On Sat, Aug 7, 2010 at 9:01 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
>> Keith,
>>
>> I worked as an engineer / field service rep for Hamilton Standard.
>>
>> When we worked with the Xian Aircraft Company in China re-designing the air
>> conditioning ducting in their Y-7 aircraft there were all kinds of 90° bends
>> in the ducting they had in that aircraft. In fact the bend in the engine
>> bleed air ducting at the juncture of the wing and fuselage was greater than
>> 90°!
>>
>> We told them the same thing and they didn't believe us either so we
>> instrumented a duct with a 90° bend with pressure pickups and demonstrated
>> the effect of the bend vis-à-vis the pressure drop.
>>
>> Unfortunately it was over 10 years ago and I don't remember the specific
>> flow rates and pressure drops.
>>
>> Regards,
>> Rob M.
>> USAussie
>>
>> -----Original Message-----
>> From: gmclist-bounces@temp.gmcnet.org
>> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Keith V
>> Sent: Saturday, August 07, 2010 10:34 PM
>> To: gmclist@temp.gmcnet.org
>> Subject: Re: [GMCnet] Exhaust Exit Question
>>
>>
>>
>> Robert Mueller wrote on Sat, 07 August 2010 20:35
>>> IIRC if you put a 90° bend in a pipe it's like
>>> adding seven feet of straight pipe vis-à-vis pressure drop.
>>
>>
>> There is no way that is even remotely true.
>> Well maybe on a high pressure fluid flow or something, but not on an already
>> over sized exhaust pipe.
>>
>> I ran a straight 90 out the back. I'm pretty sure the bumper will drag
>> before it hits.
>>
>> Jim K has a nice tailpipe in his kit, but I enjoy doing things myself and I
>> think my plain jane 90 will be darn good
>> --
>> Keith
>> 69 Vette
>> 29 Dodge
>> 75 Royale GMC
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
>
> --
> Steve Ferguson
> '76 EII
> Sierra Vista, AZ
> Urethane bushing source
> www.bdub.net/ferguson/
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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Re: [GMCnet] Exhaust Exit Question [message #95016 is a reply to message #95014] Sun, 08 August 2010 08:35 Go to previous messageGo to next message
gmcrv1 is currently offline  gmcrv1   United States
Messages: 839
Registered: August 2007
Location: Memphis
Karma: -1
Senior Member
Speedo's or nothing at all!

Tom Eckert N2VWN
73 Glacier
Oakland, TN

On Sun, Aug 8, 2010 at 7:50 AM, Pete <meandmygmcmh@gmail.com> wrote:

> I have always been told it was a gmc tradition that men wear speedo's when
> driving the coach.
>
> Pete Lyons
> New Albany in
> 76 eleganza ii
>
> Sent from my iPhone
>
> On Aug 8, 2010, at 7:11 AM, Steven Ferguson <botiemad11@gmail.com> wrote:
>
> > Rob,
> > After traveling 20+ feet from the engine, I don't think the exhaust
> > having to make a 90 deg to exit has so much as an iota of effect on
> > efficiency. If you can detect the loss of performance from this, the
> > seat of your pants is a lot thinner than mine.
> >
> > On Sat, Aug 7, 2010 at 9:01 PM, Rob Mueller <robmueller@iinet.net.au>
> wrote:
> >> Keith,
> >>
> >> I worked as an engineer / field service rep for Hamilton Standard.
> >>
> >> When we worked with the Xian Aircraft Company in China re-designing the
> air
> >> conditioning ducting in their Y-7 aircraft there were all kinds of 90°
> bends
> >> in the ducting they had in that aircraft. In fact the bend in the engine
> >> bleed air ducting at the juncture of the wing and fuselage was greater
> than
> >> 90°!
> >>
> >> We told them the same thing and they didn't believe us either so we
> >> instrumented a duct with a 90° bend with pressure pickups and
> demonstrated
> >> the effect of the bend vis-à-vis the pressure drop.
> >>
> >> Unfortunately it was over 10 years ago and I don't remember the specific
> >> flow rates and pressure drops.
> >>
> >> Regards,
> >> Rob M.
> >> USAussie
> >>
> >> -----Original Message-----
> >> From: gmclist-bounces@temp.gmcnet.org
> >> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Keith V
> >> Sent: Saturday, August 07, 2010 10:34 PM
> >> To: gmclist@temp.gmcnet.org
> >> Subject: Re: [GMCnet] Exhaust Exit Question
> >>
> >>
> >>
> >> Robert Mueller wrote on Sat, 07 August 2010 20:35
> >>> IIRC if you put a 90° bend in a pipe it's like
> >>> adding seven feet of straight pipe vis-à-vis pressure drop.
> >>
> >>
> >> There is no way that is even remotely true.
> >> Well maybe on a high pressure fluid flow or something, but not on an
> already
> >> over sized exhaust pipe.
> >>
> >> I ran a straight 90 out the back. I'm pretty sure the bumper will drag
> >> before it hits.
> >>
> >> Jim K has a nice tailpipe in his kit, but I enjoy doing things myself
> and I
> >> think my plain jane 90 will be darn good
> >> --
> >> Keith
> >> 69 Vette
> >> 29 Dodge
> >> 75 Royale GMC
> >> _______________________________________________
> >> GMCnet mailing list
> >> List Information and Subscription Options:
> >> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >>
> >> _______________________________________________
> >> GMCnet mailing list
> >> List Information and Subscription Options:
> >> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >>
> >
> >
> >
> > --
> > Steve Ferguson
> > '76 EII
> > Sierra Vista, AZ
> > Urethane bushing source
> > www.bdub.net/ferguson/
> > _______________________________________________
> > GMCnet mailing list
> > List Information and Subscription Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
_______________________________________________
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Re: [GMCnet] Exhaust Exit Question [message #95017 is a reply to message #95014] Sun, 08 August 2010 08:36 Go to previous messageGo to previous message
Ray Erspamer is currently offline  Ray Erspamer   United States
Messages: 1707
Registered: May 2007
Location: Milwaukee Wisconsin
Karma: -3
Senior Member
I finished the exhaust system yesterday......big job doing it in the driveway
crawling in and out from under that coach 9 TRILLION times the last 3 days.
But I enjoy doing things myself and it turned out great, I never dreamed the
coach could be this quiet. We previously had 2 mufflers failing with 2 pipes
that exited out the side in front of the entry door.

I started right at the headers, had two new 2 1/2 " reducer pipes made locally
and the muffler shop also supplied new header to reducer gaskets.

Those reducers went into 2 Dynomax Turbo Flow mufflers, from those I had two
10" pipes bent at approx 18 degree angles, those went between the mufflers and
a pre-made Y that I purchased.

From the Y I used a 3" 90, over to the frame rail, another 90, then straight
back until the frame raises up and then another 90 with a short extension out
the side.

I used mostly band clamps and several standard U bolt clamps, and one hanger
at the Y to hold that end of the 2 mufflers up.

Fun project and we are very pleased on how quiet it is now in the cab. Haven't
had it on the highway yet, but we'll see how that works out on sound.

Ray


Ray & Lisa Erspamer
78 Royale Center Kitchen
TZE368V101144
Wauwatosa, Wisconsin 53226
Email: 78GMC-Royale@att.net
414-745-3188
Web Site: http://ray-lisa.page.tl/




________________________________
From: Pete <meandmygmcmh@gmail.com>
To: "gmclist@temp.gmcnet.org" <gmclist@temp.gmcnet.org>
Sent: Sun, August 8, 2010 7:50:50 AM
Subject: Re: [GMCnet] Exhaust Exit Question

I have always been told it was a gmc tradition that men wear speedo's when
driving the coach.

Pete Lyons
New Albany in
76 eleganza ii

Sent from my iPhone

On Aug 8, 2010, at 7:11 AM, Steven Ferguson <botiemad11@gmail.com> wrote:

> Rob,
> After traveling 20+ feet from the engine, I don't think the exhaust
> having to make a 90 deg to exit has so much as an iota of effect on
> efficiency. If you can detect the loss of performance from this, the
> seat of your pants is a lot thinner than mine.
>
> On Sat, Aug 7, 2010 at 9:01 PM, Rob Mueller <robmueller@iinet.net.au> wrote:
>> Keith,
>>
>> I worked as an engineer / field service rep for Hamilton Standard.
>>
>> When we worked with the Xian Aircraft Company in China re-designing the air
>> conditioning ducting in their Y-7 aircraft there were all kinds of 90° bends
>> in the ducting they had in that aircraft. In fact the bend in the engine
>> bleed air ducting at the juncture of the wing and fuselage was greater than
>> 90°!
>>
>> We told them the same thing and they didn't believe us either so we
>> instrumented a duct with a 90° bend with pressure pickups and demonstrated
>> the effect of the bend vis-à-vis the pressure drop.
>>
>> Unfortunately it was over 10 years ago and I don't remember the specific
>> flow rates and pressure drops.
>>
>> Regards,
>> Rob M.
>> USAussie
>>
>> -----Original Message-----
>> From: gmclist-bounces@temp.gmcnet.org
>> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Keith V
>> Sent: Saturday, August 07, 2010 10:34 PM
>> To: gmclist@temp.gmcnet.org
>> Subject: Re: [GMCnet] Exhaust Exit Question
>>
>>
>>
>> Robert Mueller wrote on Sat, 07 August 2010 20:35
>>> IIRC if you put a 90° bend in a pipe it's like
>>> adding seven feet of straight pipe vis-à-vis pressure drop.
>>
>>
>> There is no way that is even remotely true.
>> Well maybe on a high pressure fluid flow or something, but not on an already
>> over sized exhaust pipe.
>>
>> I ran a straight 90 out the back. I'm pretty sure the bumper will drag
>> before it hits.
>>
>> Jim K has a nice tailpipe in his kit, but I enjoy doing things myself and I
>> think my plain jane 90 will be darn good
>> --
>> Keith
>> 69 Vette
>> 29 Dodge
>> 75 Royale GMC
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>> _______________________________________________
>> GMCnet mailing list
>> List Information and Subscription Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
>
> --
> Steve Ferguson
> '76 EII
> Sierra Vista, AZ
> Urethane bushing source
> www.bdub.net/ferguson/
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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Ray Erspamer 78 GMC Royale Center Kitchen 403, 3.70 Final Drive Holley Sniper Quadrajet EFI System, Holley Hyperspark Ignition System 414-484-9431
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