[Code of Federal Regulations]
[Title 40, Volume 30]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1051.230]

[Page 616]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1051_CONTROL OF EMISSIONS FROM RECREATIONAL ENGINES AND VEHICLES
--Table of Contents
 
                  Subpart C_Certifying Engine Families
 
Sec. 1051.230  How do I select engine families?

    (a) Divide your product line into families of vehicles that you 
expect to have similar emission characteristics. Your engine family is 
limited to a single model year.
    (b) Group vehicles in the same engine family if they are the same in 
all of the following aspects:
    (1) The combustion cycle.
    (2) The cooling system (water-cooled vs. air-cooled).
    (3) Configuration of the fuel system (for example, port fuel 
injection vs. carburetion).
    (4) Method of air aspiration.
    (5) The number, location, volume, and composition of catalytic 
converters.
    (6) Type of fuel.
    (7) The number, arrangement, and approximate bore diameter of 
cylinders.
    (8) Evaporative emission controls.
    (c) In some cases you may subdivide a group of vehicles that is 
identical under paragraph (b) of this section into different engine 
families. To do this under normal circumstances, you must show you 
expect emission characteristics to be different during the useful life 
or that any of the following engine characteristics are different:
    (1) Method of actuating intake and exhaust timing (poppet valve, 
reed valve, rotary valve, etc.).
    (2) Location or size of intake and exhaust valves or ports.
    (3) Configuration of the combustion chamber.
    (4) Cylinder stroke or actual bore diameter.
    (5) Exhaust system.
    (d) In some cases, you may include different engines in the same 
engine family, even though they are not identical with respect to the 
things listed in paragraph (b) of this section.
    (1) If different engines have similar emission characteristics 
during the useful life, we may approve grouping them in the same engine 
family.
    (2) If you are a small-volume manufacturer, you may group engines 
from any vehicles subject to the same emission standards into a single 
engine family. This does not change any of the requirements of this part 
for showing that an engine family meets emission standards.
    (e) If you cannot appropriately define engine families by the method 
in this section, we will define them based on features related to 
emission characteristics.
    (f) You may ask us to create separate families for exhaust emissions 
and evaporative emissions. If we do this, list both families on the 
emission control information label.