EPA-AA-SDSB-80-13
Technical Report
The Aftermarket Costs of
Heavy-Duty Diesel Mufflers
by
Daniel Heiser
July 1980
NOTICE
Technical Reports do not necessarily represent final EPA decisions
or positions. They are intended to present technical analysis of
issues using data which are currently available. The purpose in
the release of such reports is to facilitate the exchange of
technical information and to inform the public of technical devel-
opments which may form the basis for a final EPA decision, position
or regulatory action.
Standards Development and Support Branch
Emission Control Technology Division
Office of Mobile Source Air Pollution Control
Office of Air, Noise and Radiation
U.S. Environmental Protection Agency
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Summary
Aftermarket muffler costs were determined for the various
classes of heavy-duty diesel vehicles. These costs can be used
with other data to predict maintenance cost savings of eliminating
the need to replace the standard steel muffler on a heavy-duty
diesel vehicle. These aftermarket muffler costs were based on a
survey of muffler costs from a heavy-duty vehicle and engine parts
dealership. The average muffler cost for each heavy-duty diesel
vehicle class was estimated as follows (in 1980 dollars):
Class IIB-IV $136
Class V and VI $161
- Class VII $164
Class VIII $181
Introduction
EPA is preparing to propose a heavy-duty diesel particu-
late emission standard. One possible control technique is the
trap-oxidizer. The addition of a trap-oxidizer will require the
use of an exhaust system that will last the lifetime of a vehicle
(i.e., a stainless steel system). The trap-oxidizer has also been
shown to reduce engine noise as well as current mu f f lers -^/2_f
Thus, its use should eliminate the need for the muffler. This
elimination would reduce maintenance costs, since the muffler would
no longer need to be replaced. These savings would need to be
taken into account when determining the net cost per vehicle of
adding a trap-oxidizer. To estimate these savings, the aftermarket
costs of mufflers must be known. Representative aftermarket
muffler costs will thus be estimated in this report for the various
heavy-duty vehicle classes.
The method used to estimate the muffler costs for heavy-duty
diesel vehicles consists of three major steps. First, actual
aftermarket muffler costs for various heavy-duty diesel engines
will be obtained from a heavy-duty vehicle and engine parts
dealership. Second, each engine (and its muffler) will be assigned
to a particular vehicle class, based on a relationship between
engine size and gross vehicle weight. Third, an average'muffler
cost will be estimated for each vehicle class from the range of
costs available.
The average muffler costs will be determined by vehicle class
because this will be the most convenient form for future use. The
regulatory analysis for the heavy-duty diesel particulate regula-
tions will likely break down the costs of control by vehicle
class. This will be done because is it easier to predict future
sales of heavy-duty diesels by vehicle class than it is to predict
future sales of heavy-duty diesel engines .by engine family. Thus,
while muffler cost data is directly available for individual diesel
engines, additional effort will be made to covert these costs into
average muffler costs for each vehicle class. As it is likely that
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the regulatory analysis will group Classes IIB, III, and IV and
Classes V and VI together, respectively, because of the relatively
small sales in Classes III, IV, and V, that will be done here
also.
All costs will be determined in 1980 dollars. The details of
the analysis follow.
Muffler Prices
The first step in determining aftermarket muffler costs
for whole classes of heavy-duty diesel vehicles is to obtain
muffler costs for individual heavy-duty diesel engines. To do
this, a survey of muffler costs from a heavy-duty vehicle and
engine equipment supplier, A&L Parts, Inc. of Ann Arbor, Michigan,
was conducted. Most of the heavy-duty diesel mufflers sold at this
dealerships were produced by Riker Manufacturing. The description
and cost of these mufflers can be found in a Riker Manufacturing
heavy-duty engine muffler guide,4/ and a corresponding heavy-duty
muffler resale price list.^/ The engine-muffler guide listed
engine models from several diesel engine manufacturers with their
corresponding number of cylinders, the engine displacement (in
CID), the type of exhaust system (single vs. dual), and the cross
reference muffler number. The price list listed the costs of these
mufflers.
An examination of the price list showed that two different
costs were given for each muffler. These costs are known as the
"net price" and the "list price."4/ For example, the replacement
mufflers for a Cummins model V6-155 dual exhaust engine are Riker
Manufacturing mufflers, no. HD257 39 47 (p. 5-3), with each of the
two mufflers having a list price of $81.61, and a "net price" of
$54.36.J>/ (p. 5) For all the mufflers contained in the price list,
the "list price" was 50 percent higher than the "net price."
Discussion with the dealer revealed that these two costs are
related to the types of services rendered by the dealer. A dealer
selling truck parts and providing services such as installation
often sells these mufflers at or near the "list price" while a
dealer selling truck parts only would sell these mufflers closer to
the "net price." Because no data is available on how often heavy-
duty diesel owners pay each price, it will be assumed that the
average muffler cost is halfway between the "net price" and "list
price."
Further examination of .the price list also revealed that a
wide range of muffler costs exists, from a $47 muffler for an
IHC-D354 diesel engine to a $306 muffler for a Cummins V903 diesel
engine. This wide variance in costs appears primarily due to a
wide range of engine sizes, the number of exhaust systems per
engine (single vs. dual), and the number of mufflers per exhaust
system.
Vehicle-Engine Relationship ;
To categorize the muffler costs found above, each muffler
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(via its engine) will be assigned to a vehicle class. A heavy-duty
vehicle as defined by EPA is a vehicle whose gross vehicle weight
rating (GVWR) exceeds 8500 pounds. The following standard truck
classes then fall into the heavy-duty vehicle class:
Class GVWR (Pounds)
IIB 8,500-10,000
III 10,001-14,000
IV 14,001-16,000
V 16,001-19,500
VI 19,501-26,000
VII 26,001-33,000
VIII 33,001 and over
Vehicle Class IIB in this report will always refer to vehicles in
the traditional Class II category (6,000-10,000 pounds) with a
weight above 8,500 pounds (i.e., those Class II vehicles which fall
into EPA's heavy-duty vehicle category). For purposes of this
analysis, these vehicle classes will be placed into four basic
vehicle groups. These groups are:
Group GVWR (Pounds) Class
1 8,500-16,000 IIB,II,IV
2 '16,001-26,000 V,VI
3 26,001-33,000 VIII
4 33,001 and over VIII
The make-up of these groups is based on the projected future
of each of the classes^/, which is shown in Table 1. From Table 1
it can be seen that the relative sales of Classes III, IV, and V are
very small with respect to the other classes. Thus, it should be
reasonable to group Classes III and IV with Class IIB and to group
Class V with Class VI.
To facilitate the costing of mufflers for these vehicle
groups, each group will be assigned a typical engine displacement.
These engine displacements are 350 CID (Classes IIB, III, and IV),
500 CID (Class V and VI), 640 CID (Class VII) and 850 CID (Class
VIII). These engine sizes were estimated from light-duty diesel
truck and heavy-duty diesel vehicle and engine data.bj The engine
size estimated for a Class IIB-IV vehicle will be examined first.
No Class IIB-IV diesel vehicles are currently marketed.
However, General Motors (GM) does market a light-duty diesel truck
(GVWR = 6000-8500 pounds) with a 350 CID engine. As Class IIB-IV
vehicles are generally commercially-owned and operated to maximize
profit, they should not require the acceleration capabilities of a
light-duty diesel truck, which is usually personally owned. Thus,
an engine size capable of powering a 6,000-8,500 pound light-duty
diesel truck should be sufficient for vehicles potentially twice
that weight.
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Table 1
Projected Heavy-Duty Diesel Sales by Class
IIB III IV V VI VII VIII Total
1984 14,335 2,685 456 1,114 56,338 31,678 159,555 266,161
1985 18,258 3,419 581 1,418 64,275 33,725 162,578 284,255
1986 22,316 4,179 710 1,735 72,490 35,824 165,600 302,854
1987 26,511 4,965 843 2,061 80,984 37,979 168,623 321,966
1988 30,841 5,776 981 2,398 89,755 40,187 171,645 341,583
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To demonstrate that an engine size of 350 CID is at least
conceivable for a Class IIB-IV. vehicle, it can be shown that a few
vehicles even heavier than 16,000 pounds are equipped with engines
even smaller than 350 CID. For example, while most Class VIII
vehicles are equipped with engines in the 600-900 CID range, a CMC
JV-75 heavy-duty vehicle (40,000-50,0000 pounds) is usually equip-
ped with a Detroit Diesel 6V-53N engine of 318 CID.6/ Thus, a 350
CID engine should at least be a reasonable engine size for Class
IIB-IV heavy-duty diesel vehicles.
Looking next at the other extreme, Class VIII vehicles, the
average size of 850 CID reflects 1) the popular use of Cummins
engines, nearly all of which are 855 CID (rounded to 850 CID for
this analysis) and 2) that about as many engines are larger than
850 CID as are smaller than 850 CID for Class VIII vehicles.6J
Concerning Class VII vehicles, a Caterpillar 3208 engine was
known to be popular engine for many of these vehicles. The Ford
87000 is one vehicle with this engine ^6_/ The size of this engine
is 636 CID, or rounded to 640 CID for this analysis. Again, this
average engine size appears to be in the middle of a range of
engine sizes that exist for Class VII vehicles.^/ Thus, an engine
size of 640 CID was assigned to Class VII. For Class V and VI
vehicles, insufficient data were available for estimating an
average engine size. Thus, the average of the Class IIB-IV engine
size (350 CID) and the Class VII engine size (640 CID) was assumed
to be a reasonable engine size for a Class V and VI vehicle. This
comes to an engine displacement of 500 CID.
An engine's horsepower rating would be another parameter for
relating an engine to a particular heavy-duty vehicle class
and initially, would appear to be a better one. However, even here
no simple correlation exists between engine power and vehicle
class. For example, the GM heavy-duty gasoline vehicles TP-31382,
CE60, and C550 come equipped with engines having maximum brake
horsepower ratings of 240, 159, and 120, and have GVWRs of 14,500,
13,600-18,500, and 13,800-18,000 pounds, respectively. In other
words, the lightest vehicle is equipped with the most powerful
engine. In addition, a CMC CE65 vehicle(GVWR -.19,000-32,000
pounds) comes equipped with a engine having a maximum horsepower
rating of 198.j6_/ Thus, engine power does not appear to be that
more suitable than engine displacement for determining a rela-
tionship between engines and vehicles. Also, future applications
in the sizing and costing of other emission control hardware
components will most likely be done by engine size rather than by
power, since the size of cost of components are primarily related
to engine size. For example, control hardware costs for the
light-duty diesel particulate regulations were estimated according
to engine size.7/ It is likely that, a similar methodology will be
used for the proposed heavy-duty diesel particulate regulation.
Thus, it would be convenient and consistent to have a single
engine/vehicle class relationship for use in the overall analysis.
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Engines from the five largest diesel engine manufacturers,
Caterpillar, Cummins, Detroit Diesel, International Harvester, and
Mack, will be used in this analysis as these manufacturers comprise
about 97 percent of the total heavy-duty diesel engine market ^3_/
In order to determine the vehicle group to which each engine is
associated, the engine displacement of these engines (as found in.
the Riker Manufacturing engine-muffler guide)4/ will be matched to
the closest engine size determined for the four vehicle groups.
Thus, for purposes of this analysis only, a heavy-duty diesel
engine size of 0-425 CID will be assigned to Classes IIB-IV,
an engine size of 426-570 CID will be assigned to Classes V and VI,
an engine size of 571-745 CID will be assigned to Class VII, and an
engine size of 746 CID and larger will be assigned to Class VIII.
While these engine size/vehicle class relationships are not ex-
clusive in reality, they should serve the purposes of this analy-
sis. As stated above, no Class IIB-IV diesel vehicles are current-
ly marketed, so that none of the engine sizes between 0-425 CID
used here currently belong to a Class IIB-IV vehicle. However,
this analysis will assume that engines of 0-425 CID will have
muffler costs that most closely represent the muffler costs of
future Class IIB-IV diesel vehicles. For example, a Cummins.
diesel engine model V6-155 has an engine size of 378 CID and will
be assigned to Class IIB-IV in this analysis,^/ (p. 5-3) while at
present this engine is probably used to power Class VI, VII, or
VIII vehicles.
Cost Per Vehicle Group
Now that the engine-vehicle relationship has been determined,
the third step in this analysis is to estimate the average muffler
costs for each of these four groups of vehicle classes. A sales-
weighted average should provide a reasonable estimated muffler
cost for each group. However, a sales-weighted average of all
mufflers within each group can not be determined as sales data on
mufflers are not available. Another method for estimating average
costs would be to determine the relative sales of each engine sold
within each vehicle group, and then examine which mufflers are
associated with each engine, and thus indirectly develop a sales-
weighted average of mufflers costs for each vehicle group. How-
ever, this approach also has several problems. First, some heavy-
duty diesel engines have several applications other than powering
heavy-duty vehicles. For example, a given engine may be used to
power a tractor as well as an over-the-road heavy-duty vehicle.
6/ The breakdown of engines sold for each type of application is
not available. Second, even if the above breakdown were kno.wn, the
number of engines sold to power each associated heavy-duty vehicle
is not available. It is known, for example, th-at a Caterpillar
3208 or a Ford V363 engine can be used in a Ford 87000 vehicle,^/
but it is not known how many engines of each model are sold to
power this vehicle. Thus, no simple sales relationship exists
between engines and vehicles. Third, each engine used to power
heavy-duty vehicles may have many in-use applications that affect
the noise output and thus may require several different types of
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mufflers. For example, five different types of mufflers can be
used on a Cummins V555 engine.4/ Estimated sales for each type of
muffler for each engine would be difficult to predict. Thus,
a single sales-weighted muffler cost for each vehicle group can not
be determined due to the lack of sales data of either mufflers or
engines.
Another possible method for determining average muffler costs
would be to analyze the muffler costs associated with single
exhaust and dual exhaust systems within each vehicle group separ-
ately. This further breakdown should be helpful because muffler
costs appear to be much less for single exhaust systems than for
dual exhaust systems. Also, a projection of relative sales of
vehicles' with single and dual exhaust systems can be made by
assuming that turbocharged engines have single exhaust systems and
that naturally-aspirated engines have dual exhaust systems.3/
Using this assumption, approximately 3/4 of all heavy-duty diesel
vehicles will utilize a single exhaust system. This corresponds to
the fraction of turbocharged diesel engines sold by the five
largest manufacturers.^/ The remaining 1/4 of the engines (those
being naturally-aspirated) are assumed to have dual exhaust sys-
tems. While a cross-over pipe could be used instead of a dual
exhaust system on these naturally-aspirated engines, this is highly
unlikely due to their large engine size. Thus, these naturally-
aspirated engines are assumed to require two exhaust pipes and two
mufflers. This breakdown of single and dual exhaust is assumed to
apply to each vehicle class.
Because of the lack of additional sales data within each
exhaust system type, a single muffler cost for each single exhaust
and dual exhaust group of mufflers cannot be determined by a true
sales-weighing. Instead the midpoint of the range of muffler costs
within these groups will be used as the single representative
cost. In other words, the estimated value for the single exhaust
muffler and for the dual exhaust muffler for each vehicle group
will be computed by taking the midpoint of the minimum and maximum
costs listed for the two types of mufflers. If a single exhaust
system consists of two mufflers in series, then the sum of these
two mufflers will be considered as the cost of the muffler for this
exhaust system. The final average cost for each particular vehicle
group would be estimated from the predicted sales fraction of
single exhaust and dual exhaust systems determined above.
Looking first at single exhaust mufflers for a Class IIB-IV
vehicle, the least -expensive muffler '• can be found on an IHC-D35-4
engine (engine size = 354 CID). This muffler's minimum cost is $58
(halfway between net price = $47 and list price = $70). Likewise,
the most expensive Class IIB-IV single exhaust muffler can be found
on a Detroit Diesel 6V-53N engine (.engine size = 318 CID), which
costs $182. The midpoint of the minimum and maximum cost is $120,
and will be assumed to be the sales-weighted average cost of a
Class IIB-IV single exhaust muffler.
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Estimating the cost of a dual exhaust muffler on a Class
IIB-IV vehicle is done similarly as above. The least expensive
muffler can be found on a Cummins V6-155 engine (engine size =
378 CID), which has a minimum cost of SI36. The most expensive
Class IIB-IV dual exhaust muffler costs $235, and can also be
found on a Detroit Diesel 6V-53N. The midpoint of the minimum and
maximum cost is $185, which is the cost of Class IIB-IV dual
exhaust mufflers. The costs of the single and dual exhaust muf-
flers for the remaining vehicle groups were determined using the
same method as that for Class IIB-IV mufflers and can be found in
Table 2.
The final average costs of a Class IIB-IV muffler is the
estimated sales-weighted average of the single exhaust and the dual
exhaust mufflers, or $136 ((3/4 x $120) + (1/4 x $185)). Using the
same method for the remaining groups of vehicle classes, the costs
of mufflers on Class V and VI, Class VII, and Class VIII vehicles
are $161, $164, and $181, respectively. Table 3 displays a summary
of costs for each group of vehicle classes. These estimated
aftermarket costs can now be used to estimate the effect of modify-
ing or eliminating the muffler replacement schedule for heavy-duty
diesels.
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. Table
Costs of Mufflers on Single and Dual Exhaust Systems
Vehicle
Class
IIB-IV
V, VI
VII
VIII
Single
Exhaust (S)
or Dual
Exhaust (D)
S
D
S
D
s -
D
. s
Engine Equipped
with Least Expen-
sive Muffler, with
Engine Size (CID)
IHC-D354 (354 CID)
Cummins V6-155
(318 CID)
Mack END-510
(510 CID)
Cummins V8-185
(504 CID)
Caterpillar 1673T,
1674TA (638 CID)
Caterpillar 1160
(636 CID)
Cummins NH230,
Minimum
Cost I/
$ 58
$136
$ 82
$146
$ 95
$146
$119
Engine Equipped
with Most Expen-
sive Muffler, with
Engine Size (CID)
Detroit Diesel
6V-53N (318 CID)
Detroit Diesel
6V-5.3N (318 CID)
Cummins V8-185,
V8-215 (504 CID)
Detroit Diesel
8V-71N (568 CID)
Caterpillar 1150
(573 CID)
Caterpillar 1160
(636 CID)
Cummins V903
Max imum
Cost I/
$182 .
$235
$213
$255
$218
$235
$202
Midpoint of
Minimum and
Maximum Cost
$120
$185
$148
$200
$156
$190
$160
NH250, Super 250
(855 CID)
Cummins V903
(903 'CID)
$235
(903 CID)
Cummins V903
(903 CID)
o
i
$255
$245
77Halfway between "net cost" and "list cost" for each engine.
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Table 3
Costs of Mufflers, According
Group of
Vehicle
Classes
IIB-IV
V, VI
VII
VIII
to Groups
Average Single
Exhaust Cost
$120
$148
$156
$160
of Vehicle Classes
Average Dual
Exhaust Cost
$185
$200
$190
$245
Overall Average
Cost per Group
of Vehicle Classes
$136
$161
$164
$181
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References
_!/ Penninga, J., TAEB, EPA, "Second Interim Report on Status of
Particulate Trap Study," Memorandum to R. Stahman, Chief,
TAEB, EPA, August 28, 1979.
27 Alson, Jeffrey, SDSB, EPA, "Meeting Between Texaco and EPA to
Discuss Particulate Trap Work," Memorandum to the Record,
October, 1979.
_3/ "Regulatory Analysis and Environmental Impact of Final Emis-
sion Regulations for 1984 and Later Model Year Heavy-Duty
Engine," SDSB, EPA, December, 1979.
4/ "Heavy-Duty Muffler Applications," Riker Manufacturing, Inc.,
~ No. 176A, 1976.
5f "Heavy-Duty Mufflers and Exhaust System Part, Suggested List
and Resale Price," Riker Manufacturing Inc., No. 190-4, July
1, 1979.
6/ "Chiton's Automotive Industry," April, 1978, pp. 79-85, 94-95,
104-107.
TJ "Regulatory Analysis of the Light-Duty Diesel Particulate
Regulations for 1982 and Later Model Year Light-Duty Diesel
Vehicles," SDSB, EPA, February 20, 1980.
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