40 CFR 205.153 - Engine displacement.
(a) Engine displacement must be calculated using nominal engine values and rounded to the nearest whole cubic centimeter, in accordance with American Society for Testing Materials (ASTM) E 29-67.
(b) For rotary engines, displacement means the maximum volume of a combustion chamber between two rotor tip seals minus the minimum volume of that combustion chamber between those two rotor seals times three times the number of rotors.
cc=(Maximum chamber volume−minimum chamber volume) × 3 × number of rotors.
Title 40 published on 2013-07-01
no entries appear in the Federal Register after this date.