6.6 liters is 402.8 cubic inches (6,600 cc) by straight math. Makers round, so the engines sold as 6.6 L measure from 399.0 to 402.7 cubic inches.
The most common: 400.9 ci (Pontiac 400); 402.1 ci (Ford 400 (335)); 399.8 ci (Dodge 400 (B)); 402.6 ci (Chevrolet 402); 402.6 ci (Oldsmobile 403); 402.0 ci (GMC 402 (Big Block Chevy)).
| Engine | Codes | Years | Bore × stroke | Cubic inches | cc | Cylinders |
|---|---|---|---|---|---|---|
| Buick 401 (Nailhead V8) | — | 1959–1966 | 4.188" × 3.640" | 401.1 | 6,574 | 8 |
| Oldsmobile 400 (Oldsmobile V8) | W-30, L78, L66, L65 | 1965–1969 | 4.000" × 3.972" | 399.4 | 6,544 | 8 |
| Buick 400 (Buick Big-Block V8) | — | 1967–1969 | 4.040" × 3.900" | 400.0 | 6,554 | 8 |
| Pontiac 400 | L78, L65, LF4, 400 4-bbl | 1967–1980 | 4.125" × 3.750" | 400.9 | 6,570 | 8 |
| GMC 400 (Small Block Chevy) | LT4, LF6 | 1970–1976 | 4.125" × 3.760" | 401.9 | 6,586 | 8 |
| GMC 402 (Big Block Chevy) | LS3 | 1970–1972 | 4.125" × 3.760" | 402.0 | 6,587 | 8 |
| Chevrolet 402 | L34, L78, LS3, Z25 / L34 | 1970–1972 | 4.125" × 3.766" | 402.6 | 6,598 | 8 |
| American Motors 401 | — | 1971–1974 | 4.165" × 3.680" | 401.1 | 6,573 | 8 |
| Ford 400 (335) | 400 2V, 400 V-8 | 1971–1982 | 4.000" × 4.000" | 402.1 | 6,590 | 8 |
| Ram 400 (B) | B 400 | 1972–1978 | 4.339" × 3.374" | 399.0 | 6,539 | 8 |
| Dodge 400 (B) | B 400, E68, 400 2-bbl, 2-bbl | 1972–1978 | 4.342" × 3.375" | 399.8 | 6,551 | 8 |
| Jeep 401 (AMC V8) | AMC 401 | 1974–1978 | 4.165" × 3.680" | 401.1 | 6,573 | 8 |
| International 401 | V-400 | 1974 | 4.165" × 3.680" | 401.1 | 6,573 | 8 |
| Oldsmobile 403 | L80 | 1977–1979 | 4.351" × 3.385" | 402.6 | 6,598 | 8 |
| Chevrolet 403 (Duramax) | L5P, LB7 | 2001–2026 | 4.055" × 3.898" | 402.7 | 6,599 | 8 (diesel) |
| BMW 402 | N74B66 | 2017–2022 | 3.504" × 3.476" | 402.3 | 6,592 | 12 |
| Chevrolet 401 (Gen V LT) | L8T | 2020–2026 | 4.065" × 3.858" | 400.6 | 6,564 | 8 |
Cubic inches and cc are worked out from each engine's bore and stroke. Years are the model years of the factory cars on this site that list the engine.
Start with the engine code: on 1981-and-later cars and trucks it is a character of the VIN (the 8th on most American makes), and most blocks carry a code stamp. Each engine's page lists its codes and the cars it came in. See the VIN engine code lists by make.
402.8 cubic inches by straight conversion (1 liter = 61.024 cubic inches). Real 6.6 L engines measure 399.0 to 402.7 cubic inches; the table above lists each one.
6,600 cc by definition. The engines sold as 6.6 L range from 6,539 to 6,599 cc.
Makers name engines by rounded sizes. The real size comes from bore × bore × stroke × 0.7854 × cylinders, so two engines sold as the same size are often a few cubic inches apart.