What Every Member of the 

Trade Community Should Know About: 

Internal Combustion 

Piston Engines 

AN INFORMED COMPLIANCE PUBLICATION 

ARPIL 2012 
Internal Combustion Piston Engines 

April 2012 

NOTICE:

This publication is intended to provide guidance and information to the trade community. 

It reflects the position on or interpretation of the applicable laws or regulations by U.S. 

Customs and Border Protection (CBP) as of the date of publication, which is shown on 

the front cover. It does not in any way replace or supersede those laws or regulations. 

Only the latest official version of the laws or regulations is authoritative. 

Publication History 

First Published: January 1998 

Revised February 2004 

Reviewed With No Changes May 2005 

Reviewed With No Changes March 2006 

Revised August 2008 

Revised April 2009 

Reviewed With No Changes January 2010 

Revised April 2011 

Reviewed With No Changes April 2012 

PRINTING NOTE: 

This publication was designed for electronic distribution via the CBP website 

(http://www.cbp.gov) and is being distributed in a variety of formats. It was originally set 

up in Microsoft Word 2003®. Pagination and margins in downloaded versions may vary 

depending upon which word processor or printer you use. If you wish to maintain the 

original settings, you may wish to download the .pdf version, which can then be printed 

using the freely available Adobe Acrobat Reader®. 

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PREFACE 

On December 8, 1993, Title VI of the North American Free Trade Agreement Implementation 

Act (Pub. L. 103-182, 107 Stat. 2057), also known as the Customs Modernization or “Mod” Act, 

became effective. These provisions amended many sections of the Tariff Act of 1930 and 

related laws. 

Two new concepts that emerge from the Mod Act are “informed compliance” and “shared 

responsibility,” which are premised on the idea that in order to maximize voluntary compliance 

with laws and regulations of U.S. Customs and Border Protection, the trade community needs to 

be clearly and completely informed of its legal obligations. Accordingly, the Mod Act imposes a 

greater obligation on CBP to provide the public with improved information concerning the trade 

community's rights and responsibilities under customs regulations and related laws. In addition, 

both the trade and U.S. Customs and Border Protection share responsibility for carrying out 

these requirements. For example, under Section 484 of the Tariff Act, as amended (19 U.S.C. 

1484), the importer of record is responsible for using reasonable care to enter, classify and 

determine the value of imported merchandise and to provide any other information necessary to 

enable U.S. Customs and Border Protection to properly assess duties, collect accurate 

statistics, and determine whether other applicable legal requirements, if any, have been met. 

CBP is then responsible for fixing the final classification and value of the merchandise. An 

importer of record’s failure to exercise reasonable care could delay release of the merchandise 

and, in some cases, could result in the imposition of penalties. 

Regulations and Rulings (RR) of the Office of International Trade has been given a major role in 

meeting the informed compliance responsibilities of U.S. Customs and Border Protection. In 

order to provide information to the public, CBP has issued a series of informed compliance 

publications on new or revised requirements, regulations or procedures, and a variety of 

classification and valuation issues. 

This publication, prepared by the National Commodity Specialist Division of Regulations and 

Rulings is entitled "Internal Combustion Piston Engines.” It provides guidance regarding the 

classification of these items. We sincerely hope that this material, together with seminars and 

increased access to rulings of U.S. Customs and Border Protection, will help the trade 

community to improve voluntary compliance with customs laws and to understand the relevant 

administrative processes. 

The material in this publication is provided for general information purposes only. Because 

many complicated factors can be involved in customs issues, an importer may wish to obtain a 

ruling under Regulations of U.S. Customs and Border Protection, 19 C.F.R. Part 177, or to 

obtain advice from an expert who specializes in customs matters, for example, a licensed 

customs broker, attorney or consultant. 

Comments and suggestions are welcomed and should be addressed to U.S. Customs and 

Border Protection, Office of International Trade, Executive Director, Regulations and Rulings, 

799 9th Street N.W. 7th floor, Washington, D.C. 20229-1177. 

Sandra L. Bell 

Executive Director, Regulations and Rulings 

Office of International Trade 

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INTRODUCTION..........................................................................................7

TECHNICAL OVERVIEW............................................................................8

TARIFF MATTERS....................................................................................10

A. The Engines of Heading 8407........................................................................... 10

B. Aircraft Engines ................................................................................................. 11

C. Marine Propulsion Engines ............................................................................... 13

D. Reciprocating Piston Engines for Vehicles of Chapter 87 ................................. 13

E. Engines of Heading 8408 .................................................................................. 18

F. Parts of Engines (8409)..................................................................................... 19

EXAMPLES OF ENGINE PART CLASSIFICATIONS ..............................23

ADDITIONAL INFORMATION...................................................................25

The Internet................................................................................................................ 25

Customs Regulations ................................................................................................. 25

Customs Bulletin ........................................................................................................ 25

Importing into the United States ................................................................................. 26

Informed Compliance Publications............................................................................. 26

Value Publications...................................................................................................... 27

“Your Comments are Important”................................................................................. 28

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INTRODUCTION 

For people with little knowledge of how engines work, and even for those who have some 

experience, the terminology and requirements imposed by the Harmonized Tariff 

Schedule of the United States (HTSUS) for the gasoline and diesel engines of headings 

8407 and 8408 can be quite daunting. What exactly is an internal combustion engine? 

What does spark-ignition mean? How does that differ from compression-ignition? Do 

rotary engines have “pistons”? How can one tell how many cubic centimeters of cylinder 

capacity an engine has or what an engine's power output is in kilowatts if the invoice does 

not indicate this information? Which parts of gasoline and diesel engines are classifiable 

as engine parts in heading 8409 and which are classified elsewhere? 

The goal of this presentation is to set forth in straightforward language how such engines 

and their parts should be classified, and why. This will allow the importing community and 

U.S. Customs and Border Protection to have the guidance needed to classify these items 

correctly. 

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TECHNICAL OVERVIEW 

Before we examine the tariff provisions involved and get into the inner workings of the tariff 

classification process, a brief primer on engine technology is provided below. 

Most sources commonly define an engine as a machine or apparatus for converting 

energy into mechanical power or motion.1 The engine's purpose is to translate the 

potential energy locked in a fuel into a rotating force called “torque”, which is a twisting 

force or action that performs work. It is created in the engine by burning a mixture of fuel 

and air at a controlled rate. This is called “combustion” and when it occurs within the 

confines of an enclosed cylinder, it is referred to as “internal combustion”, as opposed to 

engines which burn their fuel externally like the steam engine of an old-fashioned paddle 

wheeler which employs steam raised in a fire-driven boiler to drive a piston up and down in 

a cylinder. 

Internal combustion engines are those in which power is produced by burning fuel inside a 

combustion chamber or a cylinder containing a piston which goes up and down in a 

reciprocating motion resulting from the combustion.2

 Extending down from the piston is a 

connecting rod which links the piston to the crankshaft. The connecting rod and 

crankshaft convert the reciprocating motion of the piston into a rotating motion. 

Technically, internal combustion engines can be categorized in many ways. The most 

common methods of distinguishing these engines include the combustion cycle, the valve 

location, the cooling system, the number and placement of the cylinders and the type of 

fuel used. 

Most internal combustion engines use a two or four-stroke combustion cycle. The vast 

majority of automobile engines are of the four-stroke cycle type.3

 In this type, there is an 

intake stroke, wherein the intake valve opens to admit the air/fuel mixture to be burned 

during one complete cycle.4 Next, is the compression stroke wherein the mixture is 

squeezed into a smaller volume than when first admitted into the cylinder. The power 

stroke then ignites the mixture which forcefully thrusts the piston into turning the 

crankshaft, whose power is then transmitted into a rotating motion. Finally, the exhaust 

stroke results in the opening of the exhaust valve to vent the spent gases of the power 

stroke. The rotary engine or Wankel engine (named after its inventor)5

, also uses a fourstroke cycle but does not employ conventional pistons. Instead, it uses trilobal rotors 

 

1

 Merriam-Webster’s Collegiate Dictionary, 10th ed. 383 (2001); see also, Merriam-Webster’s Online Dictionary at 

www.merriam-webster.com/dictionary/engine. 2

 See generally, How Car Engines Work: How Stuff Works at www.hotstuffworks.com/engine; see also, Internal 

Combustion Engine, at Wikipedia, The Free Encyclopedia at www.en.wikipedia.org. 3

 Id. 

4

 id. 

5

 The Wankel engine was developed by Felix Wankel, beginning with drawings and prototypes in the 1920’s. But it 

was not until the 1950s, when Wankel collaborated with a German car manufacturer, that the Wankel rotary engine 

reached the point of actual use in motor vehicles. The Wankel Engine History, Carey Russ (2004) available at 

www.autochannel.com. 

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Internal Combustion Piston Engines 

April 2012 

which function like pistons but in place of the up and down reciprocating motion of the 

piston. The rotors continually revolve in the same direction as their eccentric shafts. 

The two-stroke cycle internal combustion engine reduces these strokes from four to two 

and does not employ valves.6

 Two-stroke engines can operate at very high speeds and 

can be compact and light.7

 Thus, they are popular in small engine operations such as 

chain saws, lawn mowers, marine outboard motors and the like. They are not noted for 

fuel efficiency or emissions control. 

The engines which most dominate the fields of design and use are the V-8, V-6 and in line 

4-cylinder engines. The in-line arrangement of the engine's cylinders is self-evident while 

the V classification indicates placement of the engine's cylinders in two rows at an angle to 

each other. Another example of an engine categorized by cylinder arrangement is the 

radial engine which has been very popular for use in propeller-driven aircraft. In this 

engine all the connecting rods leading from the pistons are connected to, and rotate, a 

master rod. 

In the category of engines that are identified by valve location, the I-Head arrangement is 

in almost universal use.8

 In the I-Head engine, both the intake and exhaust valves are 

located in the engine's cylinder head, either in a straight line or staggered. 

Another method of categorizing engines is by the type of fuel used. Internal combustion 

engines may employ a wide variety of fuels, including but not limited to: gasoline, diesel 

fuel, gasohol (a mixture of gasoline and alcohol), LNG (liquefied natural gas), CNG 

(compressed natural gas) or LPG (liquefied propane gas). Internal combustion piston 

engines which ignite their fuels with a spark ignition system are classified in heading 8407. 

Compression-ignition engines 9 on the other hand, do not use an electrical ignition system, 

but rely on the heat of very high compression to ignite their heavier, less refined fuel. 

These engines are classified in heading 8408. Recent technology has developed a 

compression ignition engine which burns lighter, natural gas. This engine is excluded from 

classification in heading 8408 as the Explanatory Notes to that heading state that the 

engines of heading 8408 “operate on heavy fluid fuels”. Such compression ignition, 

natural gas fueled engines would be properly classified as “other engines” in heading 

8412. 

 

 

6

 See id. 

7

 See generally, How Two-Stroke Engines Work, Marshall Brain, at www.howstuffworks.com/two-stroke. 8

 The “I-Head” arrangement refers to a particular type of valve arrangement wherein the intake and exhaust valves 

are both mounted in a cylinder head directly above the cylinder. It is presently the most popular valve arrangement 

for gasoline and diesel engines however it is being superseded by the overhead camshaft. Arrangement of Valves, 

Integrated Publishing, available at www.tpub.com. 9

 Be advised that these are the provisions and notes which were in effect on the date of this publication and 

are used for discussion purposes only. Readers are urged to consult the current edition of these references 

for the most up-to-date information. General or special program duty rates are not included in this publication 

and one should consult the most current edition of the tariff for this information. 

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TARIFF MATTERS

Internal combustion piston engines and their parts are generally provided for in headings 

8407, 8408, and 8409, which are included in Chapter 84 of Section XVI. Yet, not all 

gasoline and diesel engines are classified in headings 8407 and 8408. Following Note 1 

(p) to Section XVI and Note 3 to Chapter 95, internal combustion piston engines which are 

for use solely or principally with the articles of Chapter 95 are to be classified with those 

articles. For example, internal combustion engines for use solely or principally in scale 

model airplanes (goods of Chapter 95) will be classified in Chapter 95 as parts of those 

scale model planes. Similarly, laboratory appliances consisting of internal combustion 

engines, along with other components, designed specially for the determination of the 

octane and cetane value of motor fuels, are classified in Chapter 90. See Section Note 

1(m), Section XVI, HTSUS. 

These exclusions aside, virtually all other types of internal combustion piston engines are 

classified in the aforementioned headings. Gasoline and diesel engines share similar 

mechanical designs and have the same essential elements as each other. These include: 

cylinders containing pistons, connecting rods, camshafts, a crankshaft, and intake and 

exhaust valves. They may have only one cylinder as with engines used on lawn mowers 

and other small lawn and garden tools, or over a dozen cylinders. Automobiles usually 

have four to eight cylinders but the diesel engines used on railway locomotives may have 

as 16 or more. 

All the engines of headings 8407 and 8408 may, at the time of importation, be equipped 

with fuel injectors, ignition parts, fuel or oil reservoirs, radiators, oil coolers, pumps for oil or 

fuel, blowers, air or oil filters, clutches or power drives, or starting devices and still remain 

engines in these headings for classification purposes. They may also be fitted with 

change speed gears or equipped with a flexible shaft and still be considered an engine.10 

A. The Engines of Heading 8407 

Heading 8407 provides for spark-ignition, reciprocating or rotary, internal combustion 

engines. There are four main subheading groups in heading 8407 covering spark-ignition 

internal combustion piston engines for: (1) aircraft (8407.10), (2) marine propulsion 

(8407.21 & 8407.29), (3) reciprocating piston engines of a kind used for the propulsion of 

vehicles of Chapter 87 (8407.31 through 8407.34) and (4) all other spark ignition internal 

combustion piston engines, including rotary (Wankel) engines (8407.90). Having 

determined that the article is a spark-ignition, reciprocating or rotary, internal combustion 

engine one must determine the sole or principal use of this engine. Guidance in this 

process is offered by Additional U. S. Rule of Interpretation 1 (a), which states: 

 “...a tariff classification controlled by use (other than actual use) is to be 

determined in accordance with the use in the United States at, or 

immediately prior to, the date of importation, of goods of that class or kind to 

 

10 See Note 3 to Section XVI, HTSUS. 

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which the imported goods belong, and the controlling use is the principal 

use[.]” 

Principal use in this context is that use which exceeds any other single use of the good. 

Following this rule one needs to know the engine’s principal use, e.g., aircraft, vessels, 

automobiles, trucks, tractors, electric generators or elsewhere. Determining the principal 

use is important to start with but there are other “use” factors which may also have to be 

considered. There are three different kinds of “uses” which come into play in the HTSUS 

provisions covering engines. As already stated, most of the classifications of heading 

8407 are based on the concept of principal use. However some provisions of this heading 

are “actual use” provisions while others are “suitable for use” provisions. This will be 

discussed infra. 

B. Aircraft Engines 

Subheading 8407.10.00 covers certain aircraft engines. You will need to know whether 

they are for use in civil aircraft or for use in an aircraft other than a civil aircraft, whether 

they are new, used, or rebuilt engines, as well as their power output in kilowatts: 

8407.10.00 Aircraft engines 

 For use in civil aircraft: 

 New: 

 20 Less than 373 kW 

 40 373 kW or over 

 60 Used or rebuilt 

 90 Other 

General Note 6 (b) (i), of the HTSUS instructs that: 

“For purposes of the tariff schedule, the term ‘civil aircraft’ means any 

aircraft, aircraft engine, or ground flight simulator (including parts, 

components, and subassemblies thereof) 

 (A) that is used as original or replacement equipment in the design, 

development, testing, evaluation, manufacture, repair, maintenance, 

rebuilding, modification, or conversion of aircraft; 

 and 

 (B) (1) that is manufactured or operated pursuant to a certificate issued by 

the Administrator of the Federal Aviation Administration (hereafter 

referred to as the ‘FAA’) under section 44704 of title 49, United States 

Code, or pursuant to the approval of the airworthiness authority in the 

country of exportation, if such approval is recognized by the FAA as 

an acceptable substitute for such an FAA certificate; [or] 

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 (2) for which an application for such certificate has been submitted to, 

and accepted by, the Administrator of the FAA by an existing type 

and production certificate holder pursuant to section 44702 of title 49, 

United States Code, and regulations promulgated thereunder; or 

 (3) for which an application for such approval or certificate will be 

submitted in the future by an existing type and production certificate 

holder, pending the completion of design or other technical 

requirements stipulated by the Administrator of the FAA. 

General Note 6 (b) (ii) goes on to say that: 

“The term ‘civil aircraft’ does not include any aircraft, aircraft engine, or 

ground flight simulator (or parts, components, and subassemblies thereof) 

purchased for use by the Department of Defense or the United States Coast 

Guard, unless such aircraft, aircraft engine, or ground flight simulator (or 

parts, components, and subassemblies thereof) satisfies the requirements of 

subdivisions (i) (A) and (i) (B) (1) or (2).” 

In simpler language, this means that for tariff purposes, the term “civil aircraft” includes: 

aircraft, aircraft engines and flight simulators (including parts, components and 

subassemblies thereof) which are (1) certified by (or for which an application for 

certification has been accepted by) the FAA or a foreign airworthiness authority recognized 

by the FAA or (2) purchased for use by the Department of Defense or the Coast Guard, if 

these goods are manufactured or operated pursuant to a certificate issued or recognized 

by the FAA. This will also include those goods, usually for testing, for which an application 

for FAA certification will be submitted to the FAA in the future. 

The testing and development provision (General Note 6(b) (i)(B)(3)) is limited to a person 

who holds an existing type and production certificate. The quantity of units that may be 

imported under this provision is limited to the amount specified in the design or technical 

requirements stipulated by the FAA. CBP may verify this information by requesting a copy 

of the design or other technical requirements sanctioned by the FAA. Post-importation 

claims may be made but no interest is payable if a refund of duty results. 

If the aircraft engine meets the definition of a “civil aircraft”, then all you will need to know 

is whether it is new, used or rebuilt. If new, you need to know its power output. Power 

output is measured in terms of kilowatts (kW) or watts (W) in the HTSUS. One kW equals 

1,000 watts. If you know the horsepower (hp) of the engine, all you need to do is to simply 

multiply that number by 0.7457 to convert it to kW and then classify it accordingly. This 

formula will apply anywhere in the tariff. See generally, NY N044484, dated December 2, 

2008. (Which classified an unassembled turbofan jet engine). 

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C. Marine Propulsion Engines 

Subheadings 8407.21 and 8407.29 deal with marine propulsion engines that are 

principally used to power the vessels of Chapter 89: 

 Marine propulsion engines: 

8407.21.00 Outboard motors 

 40 Less than 22.38 kW 

 80 Other 

8407.29.00 Other 

 10 Inboard engines with outboard drive 

 Inboard engines with inboard drive: 

 20 Less than 746 W 

 30 746 W or greater, but not exceeding 

 18.65 kW 

 40 Exceeding 18.65 kW 

A definition of “outboard motors” can be found in the Explanatory Notes to heading 8407 

which explains that: 

 The heading includes “outboard motors” for the propulsion of small boats, 

consisting of a motor of this heading, a propeller and a steering device, the 

whole constituting a single, indivisible unit. These motors, designed to be 

attached to the outside of the hull of the boat, are detachable, that is they 

can be attached and removed easily and are adjustable, the unit turning on 

the point of attachment. However, motors designed to be fixed to the inside 

of the hull at the rear of the boat combined with a block holding a steering 

propeller fixed to the exterior of the boat at the corresponding place are not 

regarded as outboard motors. 

To classify the “outboard motors” of subheading 8407.21.00 you will need to know their 

power output for appropriate statistical classification. The last sentence of the above note 

refers to marine engines known as inboard/outdrive engines which are classified in 

subheading 8407.29.0010. See NY C837313, dated January 28, 1998. Inboard engines 

with inboard drive are those engines which are located somewhere within the vessel, 

usually in a hold, and which feature a drive shaft fitted through the vessel’s hull with a 

propeller mounted at the end of the shaft. These are classified in subheadings 

8407.29.0020, 30 or 40 depending on their power output. It should be noted that the 

engines used to power personal watercraft, commonly referred to as jet skis, are classified 

as hydrojet engines in subheading 8412.29.4000. 

D. Reciprocating Piston Engines for Vehicles of Chapter 87 

The next several subheadings deal with reciprocating piston engines of a kind used for the 

propulsion of vehicles of Chapter 87. These would not include rotary engines (Wankel 

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engines) since these do not employ reciprocating pistons but trilobal rotors which act as 

pistons. Rotary engines are generally classified in subheading 8407.90. 

 Reciprocating piston engines of a kind used for the 

 propulsion of vehicles of chapter 87: 

8407.31.00 Of a cylinder capacity not exceeding 50 cc 

 40 Less than 746 W 

 80 Other 

8407.32 Of a cylinder capacity exceeding 50 cc but not 

 exceeding 250 cc: 

8407.32.10 00 To be installed in tractors suitable for 

 agricultural use 

8407.32.20 To be installed in vehicles of subheading 

 8701.20, or heading 8702, 8703 or 8704 

 40 Used or rebuilt 

 80 Other 

8407.32.90 Other 

 40 Not exceeding 18.65 kW 

 80 Exceeding 18.65 kW 

8407.33 Of a cylinder capacity exceeding 250 cc but not 

 exceeding 1,000 cc: 

8407.33.10 To be installed in tractors suitable for 

 agricultural use 

 30 Not exceeding 37.3 kW 

 Exceeding 37.3 kW: 

 60 Air-cooled 

 90 Other 

8407.33.10 (con.) To be installed in vehicles of subheading 

 8701.20, or heading 8702, 8703 or 8704: 

8407.33.30 To be installed in vehicles specially 

 designed for traveling on snow, golf 

 carts, non-amphibious all-terrain vehicles 

 and burden carriers 

 40 Used or rebuilt 

 80 Other 

8407.33.60 Other 

 40 Used or rebuilt 

 80 Other 

8407.33.90 Other 

 40 Not exceeding 18.65 kW 

 80 Exceeding 18.65 kW 

8407.34 Of a cylinder capacity exceeding 1,000 cc: 

 Of a cylinder capacity not exceeding 2,000 cc: 

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8407.34.05 To be installed in tractors 

 suitable for agricultural use 

 30 Not exceeding 37.3 kW 

 Exceeding 37.3 kW: 

 60 Air-cooled 

 90 Other 

To be installed in vehicles of subheading 

8701.20, or heading 8702, 8703 or 8704: 

8407.34.14 00 Used or rebuilt 

8407.34.18 00 Other 

8407.34.25 00 Other 

 Of a cylinder capacity exceeding 2,000 cc: 

8407.34.35 To be installed in tractors suitable for 

agricultural use 

 30 Not exceeding 37.3 kW 

 Exceeding 37.3 kW: 

 60 Air-cooled 

 90 Other 

To be installed in vehicles of subheading 

8701.20, or heading 8702, 8703 or 8704: 

8407.34.44 00 Used or rebuilt 

8407.34.48 00 Other 

8407.34.55 00 Other 

There are four major subheadings in this group and they are ordered by cylinder capacity: 

(1) Not exceeding 50 cubic centimeters (cc) (8407.31); (2) exceeding 50 cc but not 

exceeding 250 cc (8407.32); (3) exceeding 250 cc but not exceeding 1,000 cc (8407.33) 

and (4) exceeding 1,000 cc (8407.34). These subheadings have as their first point of 

departure the size of the engine’s cylinder capacity in cubic centimeters. The second 

deciding factor in classification of these engines is their use. 

In order to determine an engine’s cylinder capacity or displacement, we may need to apply 

another simple formula. Invoices for engines seldom give an engine’s cylinder capacity in 

cubic centimeters, but normally do so in terms of liters. One liter of cylinder displacement 

for an engine equals 1,000 cc. A 2.2 liter engine, therefore, equal 2,200 cc and so on. 

Once in the appropriate subheading group by cylinder capacity, you will need to know the 

tariff classification of the Chapter 87 vehicle in which the engine will be used. Each of 

these subheading groups has a three-part structure, broken out according to the class of 

Chapter 87 vehicle. The first part concerns tractors suitable for agricultural use found in 

subheadings 8701.30.10 and 8701.90.10. The second part deals with vehicles of certain 

named provisions: vehicles of subheading 8701.20 (road tractors for semi-trailers), of 

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heading 8702 (motor vehicles for the transport of 10 or more persons), of heading 8703 

(automobiles) and of heading 8704 (trucks). The last part of each of these subheading 

groups encompasses engines principally used in vehicles of Chapter 87 other than the 

foregoing. 

After you have identified the vehicle in question, proceed down to the appropriate 

subheading and find the provision appropriate to your engine. In some cases you will 

need to know whether the engine is used or rebuilt, air cooled or of a certain power output. 

The subheadings for engines to be installed in tractors suitable for agricultural use are 

actual use provisions and are governed by Additional U.S. Rule 1(b), which reads as 

follows: 

 “...a tariff classification controlled by the actual use to which the imported 

goods are put in the United States is satisfied only if such use is intended at 

the time of importation, the goods are so used and proof thereof is furnished 

within 3 years after the date the goods are entered.” 

Administrative requirements associated with this rule are spelled out in Sections 10.131 

through 10.139 of the Customs Regulations. 

The “suitability” for agricultural use referred to in these provisions is rather broad and 

encompasses those tractors which are actually, practically and commercially fit for such 

use. A tractor does not have to be principally or actually used in agriculture to fall into this 

category but its use in agricultural applications must be substantial enough to be more 

than casual, incidental, exceptional or merely possible.11 

Following the breakouts for agricultural tractors in each of the following subheading and 

heading groups is the provision for certain “named” vehicles. The engines of this group 

are of a kind which are designed to be principally used and installed in those vehicles that 

are named in each provision, such as in the vehicles of subheading 8701.20, and 

headings 8702, 8703, and 8704. In one subheading, 8407.33.30, you are further asked to 

distinguish between these general classes of named vehicles and certain special kinds of 

vehicles of those classes, namely, vehicles specially designed for traveling on snow, golf 

carts, non-amphibious all-terrain vehicles or burden carriers. Importers are reminded that 

they are required to enter engines that are designed for and to be installed in these 

“named” vehicles in the subheading provided for them and are responsible for any other 

administrative requirements that may be associated with the use of these headings. 

The last part of each of the subheading groups for engines principally used in vehicles of 

Chapter 87 constitutes the “Other” provisions, which describe engines that answer to the 

terms of the superior subheadings but which are not described in the eo nomine (which 

means “by name”) subheadings indented after them. For example, a reciprocating piston 

engine of a kind used for the propulsion of a vehicle of Chapter 87 which has a cylinder 

 

11 For more information on “tractors” and agricultural suitability, See Tractors vs. Heavy Industrial Machinery, 

Informed Compliance Publication, U.S. Customs and Border Protection (March 2006). 

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capacity exceeding 1000 cc and which is not classified in either of the two named 

provisions indented under this subheading group would fall in subheading 8407.34.5500. 

This might be an engine for industrial-type tractors or for another Chapter 87 vehicle not 

described in subheading 8701.20 or headings 8702, 8703, or 8704. 

To recap, for these “vehicles of Chapter 87” subheadings: first, determine the engine’s 

cylinder capacity in cubic centimeters (1,000 cc = 1 liter); second, know the classification 

of the Chapter 87 vehicle in question; if it is not provided for by named it is “other”; and 

last, know any special details that may be required. Also, be alert to the actual use 

subheadings and suitability questions. 

The last subheading in 8407 involves all other engines covered by the terms of the 

heading: 

8407.90 Other engines: 

8407.90.10 To be installed in agricultural or horticultural 

 machinery or equipment 

 Not exceeding 37.3 kW: 

 10 Less than 4,476 W 

 20 Other 

 Other: 

 60 Air-cooled 

 80 Other 

8407.90.90 Other 

 10 Gas (natural or LP) engines 

 Other: 

 20 Less than 746 W 

 40 746 W or greater but less than 4,476 W 

 60 4,476 W or greater but not exceeding 18.65 kW 

 80 Exceeding 18.65 kW 

All spark-ignition, reciprocating or rotary, internal combustion piston engines not described 

in any of the 3 foregoing subheading groups are classified in subheading 8407.90. This 

would include engines to be installed in agricultural or horticultural machinery or 

equipment, such as harvesters, combines, lawn mowers, hedge trimmers and the like. 

See HQ 958895, dated October 21, 1996. It also includes engines which meet the terms 

of the heading but which do not have a principal use identified in the named subheadings. 

These are engines that are not used in aircraft, marine propulsion or reciprocating engines 

for vehicles of Chapter 87. For example, industrial engines, rotary engines, natural gas 

engines and the like, none of which have a principal use in the named subheadings, are 

classified in subheading 8407.90. See NY 802897, dated October 11, 1994. 

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E. Engines of Heading 8408 

The information requirements for compression-ignition internal combustion piston engines 

are basically like those for gasoline engines. Once again, you need to know the principal 

use of the engine. The provisions of heading 8408 are broken out in 3 major subheading 

groups and are presented as follows: 

8408 Compression-ignition internal combustion piston engines 

 (diesel or semi-diesel engines): 

8408.10.00 Marine propulsion engines 

 05 Not exceeding 111.9 kW 

 15 Exceeding 111.9 kW but not exceeding 149.2 kW 

 20 Exceeding 149.2 kW but not exceeding 223.8 kW 

 30 Exceeding 223.8 kW but not exceeding 373 kW 

 40 Exceeding 373 kW but not exceeding 746 kW 

 50 Exceeding 746 kW 

8408.20 Engines of a kind used for the propulsion of vehicles 

 of chapter 87: 

8408.20.10 To be installed in tractors suitable for agricultural 

 use 

 40 Not exceeding 37.3 kW 

 80 Exceeding 37.3 kW 

8408.20.20 00 To be installed in vehicles of subheading 8701.20, 

 or heading 8702, 8703 or 8704 

8408.20.90 00 Other 

8408.90 Other engines: 

8408.90.10 To be installed in agricultural or horticultural 

 machinery or equipment 

 40 Not exceeding 37.3 kW 

 80 Exceeding 37.3 kW 

8408.90.90 Other 

 10 Not exceeding 149.2 kW 

 20 Exceeding 149.2 kW but not exceeding 

 373 kW 

 30 Exceeding 373 kW but not exceeding 746 kW 

 40 Exceeding 746 kW but not exceeding 

 1,119 kW 

 50 Exceeding 1,119 kW 

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Subheadings 8408.10 and 8408.20 are principal use provisions which cover diesel 

engines for marine propulsion and engines of a kind used for the propulsion of vehicles of 

Chapter 87, respectively. See HQ 9536870, dated July 16, 1993. Subheading 8408.90 

covers all other diesel engines, such as those for agricultural or horticultural machinery or 

equipment, locomotives, or industrial use. The same complications and cautionary advice 

arising over “actual use” and “suitable for use” seen in heading 8407 apply here as well. 

Unlike the classifications covering gasoline engines, the subheadings for diesel engines do 

not require any knowledge of cylinder capacity. They do require, however, power output 

information similar to that of heading 8407. If you have power ratings given in horsepower 

(hp), note that 1 hp equals 0.7457 kW. 

F. Parts of Engines (8409) 

Parts of engines provided for in headings 8407 and 8408 are generally classifiable under 

heading 8409. See HQ 954101, dated March 10, 1994; see also, HQ 953763, dated June 

30, 1993. According to Note 2 to Section XVI, HTSUS, if a part of an engine is not 

excluded from classification in this heading by any of the exceptions found in Note 1 to 

Section XVI, Note 1 to Chapter 84 or Note 1 to Chapter 85, then in most cases, it will be 

classifiable in 8409. The rules established by Note 2 to Section XVI are summarized as 

follows: 

 parts which are goods included in any of the headings of chapters 84 or 85 are 

to be classified in their own respective headings. For example, pumps are 

classified eo nomine in heading 8413. Likewise, compressors are classified in 

heading 8414, filtering machinery in heading 8421 and ball bearings in heading 

8482;* 

 parts that are suitable for use solely or principally with a particular kind of 

machine or with a number of machines of the same heading are to be classified 

with the machines of that kind or in one of a group of headings providing for 

such parts. (e.g., heading 8409);* 

 parts which are suitable for use solely or principally with machines of more than 

one heading or which do not have a sole or principal use are to be classified in a 

parts heading which describes them. (e.g., heading 8409).* 

* The actual text to Note 2 to Section XVI should be consulted as it identifies additional headings that 

are relevant to specific parts. Moreover, this Note does not prevail when a more specific provision 

for the part is found outside of Section XVI. See Additional U.S. Rule of Interpretation 1(c). 

Adhering to the relevant Section and Chapter Notes is critical in the classification of parts. 

The interpretation of these Notes and Additional U.S. Rule of Interpretation 1(c) can 

depend on the specific context. For example, there is a provision covering gaskets and 

other seals of plastic in Chapter 39 (subheading 3926.90.45). If you have a plastic gasket 

as a machine part it would not be classified in Chapter 39, despite the specific provision, 

but in the appropriate heading in Section XVI. This is so because the only exclusion from 

Section XVI applying to plastic goods is found in Section XVI, Note 1(a), wherein it is 

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Internal Combustion Piston Engines 

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stated that transmission, conveyor or elevator belts or belting of plastics of Chapter 39 are 

not covered by Section XVI. This is echoed by Note 2(s) of Chapter 39 which states that 

articles of Section XVI are not covered by Chapter 39. The obvious “exception” to this rule 

being the transmission, conveyor or elevator belts or belting of plastics, since such goods, 

according to the exclusionary language of Section XVI, are not articles of Section XVI. In 

practice, most engine gaskets are found to be composite goods made of more than one 

material. This can result in the need to consider which component imparts “essential 

character” in accordance with GRI 3(b). However, cylinder head gaskets and similar seals 

of metal sheeting combined with other material, or of two or more layers of metal, are 

provided for in heading 8484.12

Product designation and other associated language can also be misleading in the 

classification of engine parts. Sometimes a particular engine part may have the same 

name as an article which is specifically provided for elsewhere in the HTSUS other than as 

engines parts. However, because of it’s design or function, it may also be classified as an 

engine part. For instance, the mushroom-shaped intake and exhaust valves on engines 

are commonly known as “valves” and serve a valve-like function, but have no valve body 

and are therefore classifiable under heading 8409 rather than in heading 8481 (which 

provides for “valves” by name). Similarly, thermostats may be provided for in heading 

9032, but the “thermostats” which go in motor vehicles are actually thermostaticallycontrolled valves of heading 8481. 

The language of the HTSUS may also complicate the classification of engine parts. For 

example, transmission shafts are classifiable in HTSUS heading 8483. Generally, 

transmission shafts are articles which transmit power. Specifically, this term does not 

merely describe the transmission shaft in the transmission portion of a motor vehicle drive 

train. Consequently, any shafts which transmit power, for example the crankshaft and the 

camshaft in an engine, are classifiable under subheading 8483.10. See HQ 953271, 

dated March 12, 1993. It should be noted that those goods described in heading 8483 

which function as parts of the goods of Section XVII (motor vehicles, planes, trains and 

vessels) and which are not integral parts of engines, are classifiable in heading 8708. 13 

Most of the major components of the engines of 8407 and 8408 are classifiable under 

heading 8409. See e.g., NY 816241, dated November 22, 1995. The Explanatory Notes 

to heading 8409 specifically mention pistons, cylinders and cylinder blocks, cylinder heads, 

cylinder liners, inlet or exhaust valves, piston rings, connecting rods, carburetors and fuel 

nozzles as examples of the kind of internal combustion piston engine parts which are 

classified in this heading. Conversely, the Explanatory Notes specifically exclude: (a) 

injection pumps (heading 8413); (b) engine crankshafts, camshafts and gearboxes 

(heading 8483); and (c) electrical starting or ignition equipment such as spark plugs and 

glow plugs (heading 8511). Parts which are external to the engine itself (for example, fuel 

lines, filters and fans) are not considered to be a part of the engine for classification 

 

12 See Gaskets, Informed Compliance Publication, U.S. Customs and Border Protection (January 2006). 13 See Note 2 (e) to Section XVII, HTSUS and Note 1 (l) to Section XVI, HTSUS; see e.g., NY M81990, dated 

April 26, 2006. 

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Internal Combustion Piston Engines 

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purposes, even though they are in some form, essential to the operation of the engine. 

Only those parts which are directly incorporated into the engine itself and not excluded or 

provided for elsewhere in the HTSUS should be considered as parts of the engine. 

There are two major subheading groups in heading 8409. These are parts suitable for use 

solely or principally with the engines of headings 8407 and 8408 which are (1) for aircraft 

engines and (2) which are for all other engines. Once you get past this simple dichotomy, 

however, things get a little tricky. 

8409 Parts suitable for use solely or principally with the engines 

 of heading 8407 or 8408: 

8409.10.00 For aircraft engines 

 40 For use in civil aircraft 

 80 Other 

 Other: 

8409.91 Suitable for use solely or principally with 

 spark-ignition internal combustion piston engines 

 (including rotary engines): 

8409.91.10 Cast-iron parts, not advanced beyond cleaning, 

 and machined only for the removal of fins, 

 gates, sprues and risers or to permit location in 

 finishing machinery 

 40 For vehicles of subheading 8701.20, or 

 heading 8702, 8703 or 8704 

 60 For marine propulsion engines 

 80 Other 

 Other: 

 For vehicles of subheading 8701.20, or 

 heading 8702, 8703 or 8704: 

8409.91.30 00 Aluminum cylinder heads 

8409.91.50 Other 

 10 Connecting rods 

 81 Steel forgings 

 85 Other 

8409.91.92 For marine propulsion engines 

 10 Connecting rods 

 90 Other 

8409.91.99 Other 

 10 Connecting rods 

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April 2012 

 90 Other 

8409.99 Other: 

8409.99.10 Cast-iron parts, not advanced beyond cleaning, 

 and machined only for the removal of fins, 

 gates, sprues and risers or to permit location in 

 finishing machinery 

 40 For vehicles of subheading 8701.20, or 

 heading 8702, 8703 or 8704 

 60 For marine propulsion engines 

 80 Other 

 Other: 

8409.99.91 For vehicles of subheading 8701.20, or 

 heading 8702, 8703 or 8704 

 10 Connecting rods 

 90 Other 

8409.99.92 For marine propulsion engines 

 10 Connecting rods 

 90 Other 

8409.99.99 Other 

 10 Connecting rods 

 90 Other 

Subject to any pertinent exclusionary language and following Note 2 to Section XVI, and 

except as noted previously, parts which are suitable for use solely or principally with 

internal combustion piston aircraft engines are to be classified in subheading 8409.10. 

You will need to know whether the aircraft engine in which the engine parts are principally 

used are certified or accepted for use in civil aircraft or not. See our discussion of this 

matter under the engines of heading 8407 (discussed supra).14 

The other major subheading in this provision is for parts for all other internal combustion 

piston engines. Indented under this “Other” provision are two subheading groups: 

8409.91, which covers parts principally used in the gasoline engines of heading 8407, and 

subheading 8409.99, which covers all other parts, including those parts principally used on 

diesel engines of heading 8408 and those parts which are engine parts but not principally 

used with the engines of heading 8407. This latter kind might be a part that can be used 

equally on the engines of both headings 8407 and 8408.15 

 

14 See also General Note 6 to the HTSUS. 

15 See Note 2 (c), Section XVI. 

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Internal Combustion Piston Engines 

April 2012 

Each of these subheadings has an initial breakout covering “Cast-iron parts, not advanced 

beyond cleaning, and machined only for the removal of fins, gates, sprues and risers or to 

permit location in finishing machinery.” Caution should be exercised to be certain that 

goods entered under these subheadings are: (1) actually made of cast iron (a mill 

certificate will provide evidence of the chemical composition of this product or random lab 

testing may suffice); (2) have not been advanced beyond cleaning (a process such as 

stress relieving is permitted, but not heat treating); and (3) have not been machined 

beyond mere clean-up or have been machined merely to permit location for finishing the 

machinery. If eligible for classification in either of the “cast-iron parts” subheadings, it will 

be necessary to classify the article according to its principal use, either in certain vehicles 

(road tractors for semi-trailers, public-transport type passenger motor vehicles, motor 

vehicles for the transport of persons, or motor vehicles for the transport of goods), in 

marine propulsion engines, or in “other” than these two classes of goods. Should the castiron provisions not apply the classification of the article will be by its principal use in one of 

the three classes of goods previously enumerated. 

It is important to note that a new statistical breakout was established in 2009 for “parts: 

steel forgings” under subheading 8409.91.5081. Steel forgings are described in the 

Subheading Explanatory Notes to 7326.11 and 7326.19 as being unfinished articles that 

have been forged. Excluded under this Chapter 73 EN are “forgings which are products 

falling into other headings...or unfinished forgings which require further working but 

have the essential character of such finished products”. This is in accordance with GRI 

2(a). Therefore, forged steel parts which have the essential character of the final part, 

but are not in the final state or a part of an assembly, at the time of importation, would 

be classified under the statistical breakout as “parts: steel forgings”. 

EXAMPLES OF ENGINE PART CLASSIFICATIONS 

Under 8409 Not Under 8409 HTSUS

Carburetors Bearings 8483 

Connecting Rod Camshafts & Crankshafts 8483 

Cylinder Blocks Electronic Control Units & Sensors 9026-9032 

Cylinder Heads Fans & Turbo chargers 8414 

Cylinder Liners Filters 8421 

Fuel Nozzles Fuel Injectors (gasoline/diesel) 8481/8413 

Gaskets of Cork or Plastic Gasket Kits of Dissimilar Materials 8484 

Intake & Exhaust Manifolds Gears & Gearing 8483 

Intake & Exhaust Valves Pulleys & Non-magnetic Flywheels 8483 

Oil Pans Pumps 8413 

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Internal Combustion Piston Engines 

April 2012 

EXAMPLES OF ENGINE PART CLASSIFICATIONS 

Under 8409 Not Under 8409 HTSUS

Pistons Rubber hoses, belts & gaskets 4009/4010/4016 

Piston Rings & Pins Spark plugs, Glow Plugs & Coils 8511 

Rocker Arms Timing Chain 7315 

Valve Lifters & Seats Valves, Other than Intake & 

Exhaust 

8481 

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Internal Combustion Piston Engines 

April 2012 

ADDITIONAL INFORMATION 

The Internet 

The home page of U.S. Customs and Border Protection on the Internet’s World Wide 

Web, provides the trade community with current, relevant information regarding CBP 

operations and items of special interest. The site posts information -- which includes 

proposed regulations, news releases, publications and notices, etc. -- that can be 

searched, read on-line, printed or downloaded to your personal computer. The web site 

was established as a trade-friendly mechanism to assist the importing and exporting 

community. The web site also links to the home pages of many other agencies whose 

importing or exporting regulations that U.S. Customs and Border Protection helps to 

enforce. The web site also contains a wealth of information of interest to a broader 

public than the trade community. For instance, the “Know Before You Go” publication 

and traveler awareness campaign is designed to help educate international travelers. 

 

The web address of U.S. Customs and Border Protection is http://www.cbp.gov

Customs Regulations 

The current edition of Customs and Border Protection Regulations of the United States 

is a loose-leaf, subscription publication available from the Superintendent of 

Documents, U.S. Government Printing Office, Washington, DC 20402; telephone (202) 

512-1800. A bound edition of Title 19, Code of Federal Regulations is also available for 

sale from the same address. All proposed and final regulations are published in the 

Federal Register, which is published daily by the Office of the Federal Register, National 

Archives and Records Administration, and distributed by the Superintendent of 

Documents. Information about on-line access to the Federal Register may be obtained 

by calling (202) 512-1530 between 7 a.m. and 5 p.m. Eastern time. These notices are 

also published in the weekly Customs Bulletin described below. 

Customs Bulletin 

The Customs Bulletin and Decisions (“Customs Bulletin”) is a weekly publication that 

contains decisions, rulings, regulatory proposals, notices and other information of 

interest to the trade community. It also contains decisions issued by the U.S. Court of 

International Trade, as well as customs-related decisions of the U.S. Court of Appeals 

for the Federal Circuit. Each year, the Government Printing Office publishes bound 

volumes of the Customs Bulletin. Subscriptions may be purchased from the 

Superintendent of Documents at the address and phone number listed above. 

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Internal Combustion Piston Engines 

April 2012 

Importing into the United States 

This publication provides an overview of the importing process and contains general 

information about import requirements. The current edition of Importing Into the United 

States contains much new and revised material brought about pursuant to the Customs 

Modernization Act (“Mod Act”). The Mod Act has fundamentally altered the relationship 

between importers and U.S. Customs and Border Protection by shifting to the importer 

the legal responsibility for declaring the value, classification, and rate of duty applicable 

to entered merchandise. 

The current edition contains a section entitled "Informed Compliance." A key component 

of informed compliance is the shared responsibility between U.S. Customs and Border 

Protection and the import community, wherein CBP communicates its requirements to 

the importer, and the importer, in turn, uses reasonable care to assure that CBP is 

provided accurate and timely data pertaining to his or her importation. 

Single copies may be obtained from local offices of U.S. Customs and Border 

Protection, or from the Office of Public Affairs, U.S. Customs and Border Protection, 

1300 Pennsylvania Avenue NW, Washington, DC 20229. An on-line version is 

available at the CBP web site. Importing into the United States is also available for 

sale, in single copies or bulk orders, from the Superintendent of Documents by calling 

(202) 512-1800, or by mail from the Superintendent of Documents, U.S. Government 

Printing Office, P.O. Box 979050, St. Louis, MO 63197-9000. 

Informed Compliance Publications 

U.S. Customs and Border Protection has prepared a number of Informed Compliance 

publications in the “What Every Member of the Trade Community Should Know 

About:...” series. Check the Internet web site http://www.cbp.gov for current 

publications. 

26
Internal Combustion Piston Engines 

April 2012 

Value Publications 

Customs Valuation under the Trade Agreements Act of 1979 is a 96-page book 

containing a detailed narrative description of the customs valuation system, the customs 

valuation title of the Trade Agreements Act (§402 of the Tariff Act of 1930, as amended 

by the Trade Agreements Act of 1979 (19 U.S.C. §1401a)), the Statement of 

Administrative Action which was sent to the U.S. Congress in conjunction with the TAA, 

regulations (19 C.F.R. §§152.000-152.108) implementing the valuation system (a few 

sections of the regulations have been amended subsequent to the publication of the 

book) and questions and answers concerning the valuation system. 

Customs Valuation Encyclopedia (with updates) is comprised of relevant statutory 

provisions, CBP Regulations implementing the statute, portions of the Customs 

Valuation Code, judicial precedent, and administrative rulings involving application of 

valuation law. A copy may be purchased for a nominal charge from the Superintendent 

of Documents, Government Printing Office, P.O. Box 371954, Pittsburgh, PA 15250-

7054. This publication is also available on the Internet web site of U.S. Customs and 

Border Protection. 

The information provided in this publication is for general information 

purposes only. Recognizing that many complicated factors may be 

involved in customs issues, an importer may wish to obtain a ruling under 

CBP Regulations, 19 C.F.R. Part 177, or obtain advice from an expert 

(such as a licensed Customs Broker, attorney or consultant) who 

specializes in customs matters. Reliance solely on the general 

information in this pamphlet may not be considered reasonable care.

Additional information may also be obtained from U.S. Customs and Border Protection 

ports of entry. Please consult your telephone directory for an office near you. The 

listing will be found under U.S. Government, Department of Homeland Security. 

27
Internal Combustion Piston Engines 

April 2012 

28

“Your Comments are Important” 

The Small Business and Regulatory Enforcement Ombudsman and 10 regional 

Fairness Boards were established to receive comments from small businesses about 

Federal agency enforcement activities and rate each agency’s responsiveness to small 

business. If you wish to comment on the enforcement actions of U.S. Customs and 

Border Protection, call 1-888-REG-FAIR (1-888-734-3247). 

REPORT SMUGGLING 1-800-BE-ALERT OR 1-888-NO-DROGA 

Visit our Internet web site: http://www.cbp.gov