[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1051.230]

[Page 634-635]
 
                   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 are 
expected to have similar emission characteristics throughout the useful 
life. Except as specified in paragraph (f) of this section, you must 
have separate engine families for meeting exhaust and evaporative 
emissions. Your engine family is limited to a single model year.
    (b) For exhaust emissions, group vehicles in the same engine family 
if they are the same in all the following aspects:
    (1) The combustion cycle.
    (2) The cooling system (liquid-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) Numerical level of the emission standards that apply to the 
vehicle.

[[Page 635]]

    (c) For evaporative emissions, group vehicles in the same engine 
family if fuel tanks are similar and fuel lines are similar considering 
all the following aspects:
    (1) Type of material (including additives such as pigments, 
plasticizers, and UV inhibitors).
    (2) Emission-control strategy.
    (3) Production methods. This does not apply to differences in 
production methods that would not affect emission characteristics.
    (d) You may subdivide a group of vehicles that is identical under 
paragraph (b) or (c) of this section into different engine families if 
you show the expected emission characteristics are different during the 
useful life.
    (e) You may group vehicles that are not identical with respect to 
the things listed in paragraph (b) or (c) of this section in the same 
engine family, as follows:
    (1) You may group such vehicles in the same engine family if you 
show that their emission characteristics during the useful life will be 
similar.
    (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.
    (f) You may divide your product line into engine families based on a 
combined consideration of exhaust and evaporative emission-control 
systems, consistent with the requirements of this section. This would 
allow you to use a single engine-family designation for each engine 
family instead of having separate engine-family designations for exhaust 
and evaporative emission-control systems for each model.
    (g) Select test engines from the engine family as described in 40 
CFR 1065.401. Select test components related to evaporative emission-
control systems that are most likely to exceed the applicable emission 
standards. For example, select a fuel tank with the smallest average 
wall thickness (or barrier thickness, as appropriate) of those tanks you 
include in the same family.

[70 FR 40495, July 13, 2005]