Honda’s engine technology known as Compound Vortex Controlled Combustion is CVCC. The name describes a stratified-charge combustion system Honda developed to burn a lean overall air–fuel mixture while still igniting it reliably.
CVCC used a small auxiliary combustion chamber beside the main cylinder. A richer mixture entered this chamber near the spark plug, while the main chamber received a leaner mixture. Once ignited, the rich charge produced flame that spread through small openings and burned the leaner mixture in the main chamber.
Honda announced the technology publicly in 1972, and it reached production in the 1975 Civic. CVCC helped Honda meet demanding 1970s emissions rules without initially depending on a catalytic converter or fuel injection. It was later superseded as emissions standards tightened and Honda adopted systems such as PGM-FI.
A common mix-up is treating CVCC as an injection system: it was principally a combustion-chamber and mixture-management design, and early versions used carburetors. VTEC and i-VTEC, by contrast, concern valve timing and lift, while PGM-FI refers to programmed fuel injection.