6" SS EXHAUST STACK- OPTIONS HAVE CHANGED-I NEED YOUR VOTE!!!!

[jcmace59]

Here's a vote for the striaght pipe! But, that being said, I'd be
studying the turbo to see what size it truly is. That may be the
most restrictive element in the whole equation. Is the inlet truly 6"
and what about the outlet? Is the passage around the turbine also
enough to limit the input from the exhaust valves? I haven't studied
mine yet, so I don't have a clue as to the correct answers.



--- In WanderlodgeForum@yahoogroups.com, "Kurt Horvath"
wrote:
>
>
> Just a quick note to resolve any confusion. I never suggested the
> pipes going from 6" to 5" diameter. The opposite has been referred
to
> in relation to the original BB pipes and muffler setup. That is 5"
> pipes, 6" muffler inlet and outlet. 5" pipes traversing to a 5" or
6"
> stack up through the exhaust tunnel is fine, but I have no idea how
> going from 6" to 5" got into this thread.
>
> What a engines needs is low backpressure, but high exhaust stream
> velocity. A fast-moving but free-flowing gas column in the exhaust
> helps create a rarefaction or a negative pressure wave behind the
> exhaust valve as it opens. This vacuum helps scavenge the cylinder
of
> exhaust gas faster and more thoroughly with less pumping losses. An
> exhaust pipe that is too big in diameter has low backpressure but
> lower velocity. The low velocity reduces the effectiveness of this
> scavenging effect, which has the greatest impact on low-end torque.
>
> Low backpressure and high exhaust stream velocity can be achieved
by
> running straight-through free-flowing pipes. A well-designed, high-
> performance exhaust system typically has about 2 to 6 psi of
> backpressure. For an interesting comparison, an un-muffled straight
> pipe on a real racecar usually has 1 to 3 psi of backpressure.
> To get the least amount of backpressure, most of the good, high-
> performance mufflers available today have what is called a straight-
> through design. These mufflers quiet the exhaust by absorbing high-
> frequency vibrations in heat-resistant packing, usually consisting
of
> stainless-steel mesh and heat-resistant ceramic fibers.
>
> They typically have an inner core that is straight-through with no
> baffling at all, much like a straight pipe with many small holes in
> it. The pipe is louvered or perforated when it passes inside the
> muffler's shell, allowing sound energy to pass through the holes
but
> leaving the exhaust gas flow unimpeded. You can see straight
through
> these types of mufflers. The louvered or perforated core is usually
> wrapped with either fiberglass wadding (hence the old-school term,
> Glass Pack) or, in the better mufflers, stainless-steel mesh backed
> by ceramic fiber to help further absorb the sound. On straight-
> through mufflers, the longer the muffler and the bigger the can,
the
> quieter it is. The length usually has no effect on backpressure,
just
> noise output.
>
> Sounds Great!
>
> Unfortunately the 5" Stack that I WAS having built is 5" outside
> diameter, with a 3" interior straight through section. Poor
> communication between me and the fabricator, similar to the 6" to
5"
> error discussed in past posts.
>
> A muffler designed with a 5" diameter core would have a 7" or 8"
> outside diameter and is cost prohibitive in SS
>
> New Options:
>
> 1 - Use two of these 5" stacks at doubled the cost.
> 2 - Go back to a standard muffler.
> 3 - Stainless Steel Muffler 5" in & out
> 4 - STRAIGHT PIPE
>
> Because today is election day.
>
> I'd like to throw this out there for a general vote.
>
> What would your choice be???????
>
> 1, 2, 3, or 4
>
> Thanks for all the help.
>
> Kurt Horvath
> 95 PT 42
> 10AC
>
> --- In WanderlodgeForum@yahoogroups.com, "Joyce and Richard Hayden"
> wrote:
> >
> > Rob,
> > The elbow I'm going to have to replace is the one that is 90deg+
> going into the muffler. It's not a standard 90deg bend. My pyro
> tube is just down wind of the turbo in the 180deg bend. The exh.
> exits on the curb side.
> >
> > Dick Hayden - '87 PT 38 - Lake Stevens, WA
> >
> > ----- Original Message -----
> > From: Rob Robinson
> > To:
> WanderlodgeForum@yahoogroups.com > om>
> > Sent: Monday, November 03, 2008 12:25 PM
> > Subject: Re: [WanderlodgeForum] Re: 6" SS EXHAUST STACK
> >
> >
> > Richard I just replaced that elbow you are speaking of. It
> wasn't hard to find. In fact I had my supplier Mac Industrial
Exhaust
> Vancouver BC modify it with a longer end on the end that goes into
> the pyro tube that goes directly into the turbo. Call me if you
need
> more info 250 590-8050
> >
> >
> >
> > 2008/11/3 Joyce and Richard Hayden
> >
> >
> >
> > Kurt & David and others who might be following this
discussion
> as I have.
> >
> > When you introduced the Bernoulli's Equation into this
> discussion I figured it was time to ask my brother for help. He
has
> some background with advanced math and has been helpful to another
of
> our group in the past. I forwarded to him the messages at the
bottom
> to give him some background and data that had already been
offered.
> I notice now that this subject has died down somewhat so far today
> but here is his message to me anyway. I am not going to pretend
that
> I understand all of it but it seems that going from 6" to 5" isn't
> going to be the end of the world. I know you two have Series 60
> engines and I have the older 8v92 but the problem is the same and I
> have discovered a holds in the elbow that goes into the muffler.
> That elbow is probably unobtainable or if it is would be quite
> expensive. So, I was considering 5" as many others have.
> >
> > Any, here is my brother Steve Hayden's response to me -
> unedited:
> >
> >
> > Brother,
> >
> >
> >
> > You have stretched the limits of my memory on this one! The
> last time I thought about fluid flow and the Bernoulli Principal
was
> probably 40 or so years ago. Not to worry; it is fun to fire up the
> old neurons. I'll try to answer your question below. The response
> isn't technically rigorous as some of your forum buddies may point
> out. It does seem to make sense though.
> >
> >
> >
> > As I understand the question, it goes something like this.
Does
> changing the diameter of the exhaust system on the bus from six
> inches to five inches result in any noticeable decrease in
> performance? I understand that the exhaust system runs from the
> manifolds to a turbocharger and then out through a muffler to the
> atmosphere. If one constricts the exhaust from the outlet of the
> turbocharger which results in a higher pressure at the output, then
> the turbocharger efficiency decreases. Have I got that about right?
> >
> >
> >
> > If so, then the answer is changing from six inch diameter to
> five inch is very unlikely to result in any detectable decrease in
> performance. Here's the logic I used to reach this conclusion.
> >
> >
> >
> > To make the calculation, one uses one of the forms of
> Bernoulli's Equation. I saw in one of the posts you sent me a
> reference to a nice discussion of Bernoulli's Equation. This
> discussion is correct in that it points out that Bernoulli's
Equation
> is an energy conservation equation which means you can't get
> something for nothing. This equation only holds when no outside
work
> is being done on the system nor is the system doing any work on the
> outside. Consequently, as was pointed out in the posting, the
> Bernoulli Equation applies to the ideal situation of, for example,
> non-compressible gas, laminar flow (non-turbulent), no friction
with
> the pipe walls and so on.
> >
> >
> >
> > Accounting for these non-ideal conditions from first
principles
> is tedious and usually results in equations that cannot be solved
in
> closed form. Engineers get around this by putting correction terms
in
> the equation and then determining the coefficients of the
correction
> terms by experimentation. This is a science within itself and not
as
> easy as I just made it sound. Fortunately, engineers have been
> interested in fluid, including gas, flow in pipes for such
> applications as gas and oil pipelines and have derived equations
for
> these applications. I did find an on-line calculator at
>
http://www.pipeflowcalculations.com/<http://www.pipeflowcalculations.c
> om/> which I used to make my analysis.
> >
> >
> >
> > Of course, I had to make some assumptions to plug into the
> calculator. With your help, I came up with the flowing. The amount
of
> exhaust gas that must be expelled out the exhaust pipe per unit
time
> was 24,000 liters/min. You estimated this from the displacement of
> the engine cylinders times the number of cylinders times the rpm of
> the engine. We also agreed that the length of pipe from the
> turbocharger to the exhaust outlet at 7 feet and the temperature of
> the exhaust at 500 F. I assumed the exhaust pipe was smooth with a
> roughness of lest than one thousandth of an inch. The local
> resistance coefficient which accounts for bends in the exhaust pipe
> and other local constraints was tougher. I used the calculator
> default value of 1 but also did a sensitivity analysis.
> >
> >
> >
> > Since the pressure at the exhaust pipe outlet is atmospheric
> (14.7 psi), I calculated the pressure drop from the turbocharger
> outlet to atmosphere along the length of the exhaust pipe for
> different pipe diameters. The result is shown graphically below.
> >
> >
> >
> >
> >
> >
> >
> > Note that the pressure drop axis is logarithmic. So the
> difference in pressure drop between a 5 and 6 inch diameter pipe is
> only about 0.15 psi. In fact, the pressure drop is less than 1 psi
> for exhaust pipes 3.5 inches and larger.
> >
> >
> >
> > I did change the local resistance coefficient to see the
> effect. At the default value of 1 and for a 5 inch diameter pipe,
the
> pressure drop is 0.25 psi. An order of magnitude less at 0.1
results
> in a pressure drop of 0.09 psi and an order of magnitude larger at
> 10, 1.8 psi.
> >
> >
> >
> > I don't know what the pressure at the turbocharger input is
but
> seems unlikely that a pressure change of 1 psi or less at the
> turbocharger output would result in a detectable decrease in
> performance. Perhaps someone on your forum has this number.
> >
> >
> >
> > Since many systems are over designed to have a safety margin,
> it also seems to make sense that changing to 5 inch diameter from 6
> inch should make little difference.
> >
> >
> >
> > Hope this helps. Feel free to cut and paste onto the forum if
> you like. Any questions, you know where I live.
> >
> >
> >
> > Steve
> >
> >
> >
> >
> > ----- Original Message -----
> > From: Kurt Horvath
> > To:
> WanderlodgeForum@yahoogroups.com > om>
> > Sent: Friday, October 31, 2008 8:24 PM
> > Subject: [WanderlodgeForum] Re: 6" SS EXHAUST STACK
> >
> >
> >
> > David,
> >
> > A few days ago you were all for a straight pipe.
> >
> > Now we have delved into the effects and merits of
> the, "Bernoulli
> > effect" it presumes that the density of the flowing gas is
> constant,
> > which will not necessarily be true in this application.
> >
> > If this were a consideration and a factor in design and
> function
> > wouldn't this be a standard application on all exhausts,
> considering
> > today's drive for better performance Vs energy expended Vs
> > particulate
> > matter expelled Vs whatever else the EPA thinks we should
be
> > ejecting from our exhaust pipes?
> >
> > One factor you may have not considered are the exhaust
> blankets I
> > mentioned. They will retain the heat within the pipes thus
> increasing
> > the velocity of the exhaust creating an accelerated flow of
> gasses
> > through the tubes.
> >
> > If I may present another observation, 5" exhaust systems
are
> the
> > standard on all production class 8 trucks.
> >
> > Furthermore and for the heck of it I don't believe that the
> trucker
> > that has 8" stacks on his rig has considered
the, "Bernoulli
> effect"
> > in his choice at the Chrome Shop. Although it mat have an
> effect on
> > performance further than just looking cool. They do look
> good, no
> > doubt.
> >
> > For the last four weeks I have queried Detroit Diesel,
Custom
> Exhaust
> > Fabricators, Several OEM Exhaust Mfg.'s, Marine Exhaust
> Engineers &
> > Fabricators, My BB Guru, and anyone else that would lend an
> ear, and
> > no one has expressed any apprehension or regard in the
> respect to a
> > 5" exhaust system. In fact all parties expressed their
> surprise in
> > respect as to why the system would change size at the
muffler.
> >
> > Several owners have modified their systems to 5" from end
to
> end, and
> > have seen no change in performance. Positive or negative,
In
> general
> > it was just a matter of convenience in acquiring parts, I
> won't get
> > into that. That has recently been beaten to death at the
> expense of
> > all parties involved
> >
> > If there is someone who would like to further this debate
> with
> > Imperical evidence of the merits of, or placing a venturi
> somewhere
> > in this exhaust system I have pasted a site below where you
> can
> > formulate your calculations. I would love to see some
> evidence of a
> > positive effect, in which case I would have no problem in
> adding a
> > venturi crimp in the exhaust system.
> >
> > Bernoulli Calculation
> >
> > http://hyperphysics.phy-
> astr.gsu.edu/Hbase/pber.html#beq<http://hyperphysics.phy-
> astr.gsu.edu/Hbase/pber.html#beq>
> >
> > The calculation of the "real world" pressure in a
> constriction of a
> > tube is difficult to do because of viscous losses,
> turbulence, and
> > the assumptions which must be made about the velocity
profile
> (which
> > affect the calculated kinetic energy). The model
calculation
> here
> > assumes laminar flow (no turbulence), assumes that the
> distance from
> > the larger diameter to the smaller is short enough that
> viscous
> > losses can be neglected, and assumes that the velocity
> profile
> > follows that of theoretical laminar flow. Specifically,
this
> involves
> > assuming that the effective flow velocity is one half of
the
> maximum
> > velocity, and that the average kinetic energy density is
> given by one
> > third of the maximum kinetic energy density.
> >
> > Now if you can swallow all those assumptions, you can
model*
> the flow
> > in a tube where the volume flow rate is = cm3/s and the
fluid
> density
> > is ñ = gm/cm3. For an inlet tube area A1= cm2 (radius r1
> =cm), the
> > geometry of flow leads to an effective fluid velocity of v1
> =cm/s.
> > Since the Bernoulli equation includes the fluid potential
> energy as
> > well, the height of the inlet tube is specified as h1 = cm.
> If the
> > area of the tube is constricted to A2=cm2 (radius r1 = cm),
> then
> > without any further assumptions the effective fluid
velocity
> in the
> > constriction must be v2 = cm/s. The height of the
constricted
> tube
> > is specified as h2 = cm.
> >
> > The kinetic energy densities at the two locations in the
tube
> can now
> > be calculated, and the Bernoulli equation applied to
> constrain the
> > process to conserve energy, thus giving a value for the
> pressure in
> > the constriction. First, specify a pressure in the inlet
tube:
> > Inlet pressure = P1 = kPa = lb/in2 = mmHg = atmos.
> > The energy densities can now be calculated. The energy unit
> for the
> > CGS units used is the erg.
> >
> > Inlet tube energy densities
> > Kinetic energy density = erg/cm3
> > Potential energy density = erg/cm3
> > Pressure energy density = erg/cm3
> > Constricted tube energy densities
> > Kinetic energy density = erg/cm3
> > Potential energy density = erg/cm3
> > Pressure energy density = erg/cm3
> >
> >
> > The pressure energy density in the constricted tube can now
> be
> > finally converted into more conventional pressure units to
> see the
> > effect of the constricted flow on the fluid pressure:
> >
> > Calculated pressure in constriction =
> > P2= kPa = lb/in2 = mmHg = atmos.
> >
> > This calculation can give some perspective on the energy
> involved in
> > fluid flow, but it's accuracy is always suspect because of
> the
> > assumption of laminar flow. For typical inlet conditions,
the
> energy
> > density associated with the pressure will be dominant on
the
> input
> > side; after all, we live at the bottom of an atmospheric
sea
> which
> > contributes a large amount of pressure energy. If a drastic
> enough
> > reduction in radius is used to yield a pressure in the
> constriction
> > which is less than atmospheric pressure, there is almost
> certainly
> > some turbulence involved in the flow into that
constriction.
> > Nevertheless, the calculation can show why we can get a
> significant
> > amount of suction (pressure less than atmospheric) with
> > an "aspirator" on a high pressure faucet. These devices
> consist of a
> > metal tube of reducing radius with a side tube into the
> region of
> > constricted radius for suction.
> >
> > *Note: Some default values will be entered for some of the
> values as
> > you start exploring the calculation. All of them can be
> changed as a
> > part of your calculation.
> >
> > Kurt Horvath
> > 95 PT 42
> > 10AC
> >
> > > > > >
> > > > > > --- In
> WanderlodgeForum@yahoogroups.com > 40yahoogroups.com>
> > > > > 40yahoogroups.com>
> > > > > > > 40yahoogroups.com>,
> David Brady
> >
> > > > > > wrote:
> > > > > > >
> > > > > > > Hi Kurt,
> > > > > > >
> > > > > > > No thanks, I already have a stock muffler. Thanks
> for the
> > links,
> > > > > > > there's some pretty nifty items there. Be careful
> with
> > those fancy
> > > > > > > braided stainless steel pieces. They look sharp,
> but
> > they've always
> > > > > > > leaked on my turbocharged subaru wrx. Kurt,
you've
> been
> > around
> > > > > > > a few over-the-road coaches, Prevost' and what
not,
> what do
> > they
> > > > > > > run on their exhaust systems; i.e., expansion
> pipes, flex
> > pipe, etc.
> > > > > > >
> > > > > > > David Brady
> > > > > > > '02 LXi, NC
> > > > > > >
> > > > > > > Kurt Horvath wrote:
> > > > > > > >
> > > > > > > > David, Would you like to take that brand new
> muffler off
> > my
> > > > > > hands???
> > > > > > > >
> > > > > > > > According to DD straight pipe & ECU will not
have
> any
> > issues in
> > > > > > the
> > > > > > > > 95 vintage S 60.
> > > > > > > >
> > > > > > > > OEM built that pipe for BB ACAP - As Cheep As
> Possible -
> > > > > > > >
> > > > > > > > The original routing of the pipe leaves the
> turbo, source
> > of the
> > > > > > > > first failure, cracked the 1st 90 degree turn a
> short
> > straight run
> > > > > > > > 2nd. 90 degree turn, then into a double ball
> connector
> > that also
> > > > > > > > telescopes in and out. You can check out that
> piece of S--
> > -, sorry
> > > > > > > > engineering wonder here.
> > > > > > > >
> > > > > > > >
> >
http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->
> > > >
> <http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->>
> > > > > >
> <http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->
> >
> > > >
> <http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->>>
> > > > > > 89.pdf
> > > > > > > >
> >
<http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->
> > > >
> <http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->>
> > > > > >
> <http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->
> >
> > > >
> <http://www.dynaflexproducts.com/download...g_03_pg70-
> <http://www.dynaflexproducts.com/download...g_03_pg70->>>
> > > > > > 89.pdf>
> > > > > > > >
> > > > > > > > Page 76 Double Ball Joint with Slip Joint
Feature
> > Allowing Lateral
> > > > > > > > Movement length 16 to 18 inches mine measures
> 14 .55
> > inches at
> > > > > > > > present. This marvel allows for 10 degrees of
> angularity
> > 360
> > > > > > degree
> > > > > > > > rotation 2" of offset 2" axial movement,. Hell
> the u
> > joints can't
> > > > > > > > move around that much. Besides it was hard
> clamped to the
> > mount
> > > > > > from
> > > > > > > > the engine in front of this connection not to
> mention
> > rusted to
> > > > > > the
> > > > > > > > point that it took an pneumatic impact chisel
to
> get it
> > apart.. So
> > > > > > > > what's the point. You need flex in between the
> turbo and
> > the first
> > > > > > > > mount.
> > > > > > > >
> > > > > > > > The Flex Connector with liner I choose is here
at
> > > > > > > >
> > > > > > > >
> http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>
> > > > <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>>
> > > > > >
> <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>
> > > > <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>>>
> > > > > > > >
> <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>
> > > > <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>>
> > > > > >
> <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>
> > > > <http://vibrantperformance.com/catalog/product_info.php?
> <http://vibrantperformance.com/catalog/product_info.php?>>>>
> > > > > > > >
> > > > > >
> >
>
cPath=1022_1035_1064_1114&products_id=1008&osCsid=999d7ef5fdd15864bae3
> > > > > > > > 3db41abf5ef9
> > > > > > > >
> > > > > > > > The 2 90 degree turns were fabricated in that
> manner
> > because it's
> > > > > > not
> > > > > > > > easy to bend large diameter pipe in a single
180
> degree
> > bend, thus
> > > > > > > > they weld 2 90's together, which is the
industry
> standard
> > for
> > > > > > > > manufacturing a 180 degree turn in large pipe
> exhausts.
> > Well this
> > > > > > > > ain't the factory and we're not constrained by
> what is
> > easy. I
> > > > > > have
> > > > > > > > acquired a 14ga 180 degree U-Tube that has the
> same
> > external
> > > > > > > > dimensions as the original pipe. I'm not an
> engineer but I
> > > > > > reasonably
> > > > > > > > certain that with the remaining 90 degree bend
> and a 45
> > degree
> > > > > > bend
> > > > > > > > there will be sufficient back pressure.
> > > > > > > >
> > > > > > > > There will also be a flexible pipe hanger mount
> behind
> > the Flex
> > > > > > > > connector mounted on the ceiling of the engine
> > compartment that
> > > > > > will
> > > > > > > > support the middle section of pipe and will
allow
> for any
> > movement
> > > > > > > > and or torque that may be transferred to the
pipe
> by the
> > motor.
> > > > > > The
> > > > > > > > original clamps for the muffler have to go as
> they are 6"
> > but the
> > > > > > > > rubber isolated mounting bars will remain and
> that's all
> > that was
> > > > > > > > there to begin with. So where's the rub? Bub!
> > > > > > > >
> > > > > > > > Not to take anything away from the engineers
that
> > designed the
> > > > > > Bird,
> > > > > > > > But there are some glaring deficiencies. 7 way
> trailer
> > plug, Air
> > > > > > > > Purge System, Watts valve, Accelerator and
Brake
> peddles,
> > Front
> > > > > > Left
> > > > > > > > Shock Mount, Relay for Jake Brake, W/D Vent for
> Slendide
> > 2000,
> > > > > > > > Installation of Refrigerator with inadequate
> convection,
> > The seat
> > > > > > > > belts mounted to floor instead of the seat,
That
> reminds
> > me I
> > > > > > still
> > > > > > > > have to fix that one. Nothing like hitting a
road
> > transition just
> > > > > > to
> > > > > > > > have the air ride seat bounce and the seat
belts
> > automatically
> > > > > > adjust
> > > > > > > > for the slack then the air ride seat rebounds
and
> the
> > belts try to
> > > > > > > > cut you in half at the waist. That's just the
95
> PT 42.
> > I'm not
> > > > > > > > bitchin! I'm fixin
> > > > > > > >
> > > > > > > > Kurt Horvath
> > > > > > > > 95 PT 42
> > > > > > > > 10AC
> > > > > > > >
> > > > > > > > --- In
> WanderlodgeForum@yahoogroups.com > 40yahoogroups.com>
> > > > > 40yahoogroups.com>
> > > > > > > 40yahoogroups.com>
> > > > > > > > > 40yahoogroups.com>,
> David Brady
> >
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > > Kurt,
> > > > > > > > >
> > > > > > > > > I agree with Greg. I'm gonna keep mine stock.
> There's a
> > bunch
> > > > > > > > > of vibration and movement back there. I
figure
> BB's been
> > > > > > building
> > > > > > > > > buses a whole lot longer than I have.
Initially
> I'd
> > scratch my
> > > > > > > > > head when looking at the frame and support
> pieces, but
> > when
> > > > > > > > > you consider that something as big as a bus
> must twist
> > and flex,
> > > > > > > > > this flexibility needs to be designed in.
Make
> one piece
> > > > > > stronger
> > > > > > > > > and you've created a stress raiser someplace
> else.
> > > > > > > > >
> > > > > > > > > I have a friend who transplanted a honda v-
tech
> motor
> > into a
> > > > > > > > > lotus elise. Everything worked but the
> alternator
> > mount. The
> > > > > > mount
> > > > > > > > > insists on cracking. There can be some weird
> harmonics
> > and
> > > > > > > > > resonant frequencies going on that are
> difficult to
> > grasp and
> > > > > > > > > only trial and error and a 50 year track
record
> of
> > building
> > > > > > buses
> > > > > > > > > can solve (unless you can model it and run
high
> powered
> > > > > > > > > computer finite element analysis on it). He's
> still
> > fighting
> > > > > > that
> > > > > > > > > mount...
> > > > > > > > >
> > > > > > > > > Okay, I'm off my soap box.
> > > > > > > > >
> > > > > > > > > David Brady
> > > > > > > > > '02 LXi, NC
> > > > > > > > >
> > > > > > > > > Gregory OConnor wrote:
> > > > > > > > > >
> > > > > > > > > > Kurt, try and figure why there were 4
bends.
> it may
> > be that
> > > > > > it was
> > > > > > > > > > engineered to alow for swing room between
> the 'hung
> > exhaust'
> > > > > > and
> > > > > > > > > > the 'torque reaction of the ruber mounted
> detroit'.
> > look at
> > > > > > the
> > > > > > > > roll
> > > > > > > > > > of the torque and see that there is a place
> for the
> > movement
> > > > > > to
> > > > > > > > twist
> > > > > > > > > > a union. I kinda think this movement was
the
> problem
> > with the
> > > > > > > > > > resulting crack.
> > crack=result ;movement=cause ;facilitate
> > > > > > movement
> > > > > > > > > > =repair. may be that BB enginered it
correct
> but
> > someone
> > > > > > > > > > overtightened a band to cure an exhaust
> leak???????
> > you also
> > > > > > got
> > > > > > > > to
> > > > > > > > > > keep the stack from cantilivering off of
the
> maniford
> > with
> > > > > > your
> > > > > > > > new
> > > > > > > > > > design. Scavenging is one variable in fuel
> > efficiency. even
> > > > > > > > straight
> > > > > > > > > > pipes some time will result in lower fuel
> economy
> > because the
> > > > > > > > intake
> > > > > > > > > > variable get screwd. backpressure is mathed
> into the
> > computer.
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > --------------------------------------------
--
> --------
> > ----
> > > > > > > > ------
> > > > > > > > > >
> > > > > > > > > > Internal Virus Database is out-of-date.
> > > > > > > > > > Checked by AVG.
> > > > > > > > > > Version: 7.5.405 / Virus Database:
> 270.8.0/1715 -
> > Release
> > > > > > Date:
> > > > > > > > 10/9/2008 12:00 AM
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > ------------------------------------------------
--
> --------
> > > > > > ------
> > > > > > > >
> > > > > > > > Internal Virus Database is out-of-date.
> > > > > > > > Checked by AVG.
> > > > > > > > Version: 7.5.405 / Virus Database:
270.8.0/1715 -
> Release
> > Date:
> > > > > > 10/9/2008 12:00 AM
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > --------------------------------------------------------
--
> > > > > >
> > > > > > Internal Virus Database is out-of-date.
> > > > > > Checked by AVG.
> > > > > > Version: 7.5.405 / Virus Database: 270.8.0/1715 -
> Release
> > Date:
> > > > 10/9/2008 12:00 AM
> > > > > >
> > > > >
> > > >
> > > >
> > > > --------------------------------------------------------
--
> > ------
> > > >
> > > > Internal Virus Database is out-of-date.
> > > > Checked by AVG.
> > > > Version: 7.5.405 / Virus Database: 270.8.0/1715 -
Release
> Date:
> > 10/9/2008 12:00 AM
> > > >
> > >
> >
> >
> >
> >
> >
> >
> >
> >
> > --
> > Rob, Sue & Merlin Robinson
> > 94 WLWB
> >
>