Question: Designed by Chevrolet, this engine shared bore diameter and some parts with General Motors X engine.

Context paragraphs:
6.45×48mm XPL Swiss: 6.45x48mm XPL Swiss (or 6.45x48 GP 80) is an experimental intermediate rifle cartridge that was developed in conjunction with the SIG SG 550 rifle as a potential successor to the 7.5×55mm Schmidt–Rubin cartridge.  The rimless cartridge has a base diameter of 11.82 mm (similar to the 7.62×51mm NATO) and a case length of 47.72 mm.  The bullet is an unusual 6.65 mm diameter (6.45mm refers to the bore diameter), fractionally smaller than the common 6.5 mm (bore diameter) bullet.  The 6.3 g bullet was fired at a muzzle velocity of 900 m/s with 2,550 J of muzzle energy.

Ferrari flat-12 engine: The Ferrari flat-12 engine family is a series of 180° V12 DOHC petrol engines produced by Ferrari from 1973 to 1996.  Introduced with the 365 GT4/BB, this engine shared its construction with the flat-12 race-engines used in the 312B and 312 PB, but its displacement, bore & stroke, rods and pistons were the same as the "Tipo 251" 60° V12 Colombo engine powering the Daytona it replaced.

Chevrolet: Chevrolet ( ), colloquially referred to as Chevy and formally the Chevrolet Division of General Motors Company, is an American automobile division of the American manufacturer General Motors (GM).  Louis Chevrolet and ousted General Motors founder William C. Durant started the company on November 3, 1911 as the Chevrolet Motor Car Company.  Durant used the Chevrolet Motor Car Company to acquire a controlling stake in General Motors with a reverse merger occurring on May 2, 1918 and propelled himself back to the GM presidency.  After Durant's second ousting in 1919, Alfred Sloan, with his maxim "a car for every purse and purpose," would pick the Chevrolet brand to become the volume leader in the General Motors family, selling mainstream vehicles to compete with Henry Ford's Model T in 1919 and overtaking Ford as the best-selling car in the United States by 1929.

General Motors 60° V6 engine: The General Motors 60° V6 engine family is a series of 60° V6 engines which were produced for both longitudinal and transverse applications.  All of these engines are 12-valve cam-in-block or overhead valve (OHV) engines, except for the LQ1; which uses 24-valves driven by dual overhead cams (DOHC) instead.  These engines vary in displacement between 2.5 and 3.4 liters and have a cast iron block and either cast iron or aluminum heads.  Production of these engines began in 1980 and ended in 2005 in the U.S., with production continued in China until 2010.  This engine family was the basis for the GM High Value engine family.  Some refer to these engines as X engines due to first usage in the X-body cars.

Chevrolet Opala: The Chevrolet Opala was a Brazilian mid-size car sold under the Chevrolet brand in South America from 1969 to 1992, by General Motors do Brasil.  It was derived from the German Opel Rekord Series C, Opel Commodore Series A, but used USA-sourced engines and Holden styling.  Two four-cylinder engines: the Chevrolet 153ci 4-cylinder from Chevy II/Nova, which later got a new crankshaft stroke and cylinder bore, changing its size to 151ci (usually mistaken for the Pontiac Iron Duke engine), and the six-cylinder 250 from the contemporary line of North American car/light truck production.  GM manufactured about one million units including the Opala sedan, Opala Coupé, and the station wagon variant, the Opala Caravan.  It was replaced by the Chevrolet Omega in 1992, also an Opel spinoff.  It was the first passenger car built by GM in Brazil by the General Motors do Brasil division.  A luxury version of the Opala was marketed as the Chevrolet Diplomata.

Sabot: A sabot (UK and Int.: , ), (US: ) is a structural device used in firearm or cannon ammunition to keep a sub-caliber flight projectile, such as a relatively small bullet or arrow-type projectile, in the center of the barrel when fired, if the bullet has a significantly smaller diameter than the bore diameter of the weapon used.  The sabot component in projectile design is more than simply the relatively thin, tough and deformable seal known as a driving band or obturation ring needed to trap propellant gases behind a projectile, and also keep the projectile centered in the barrel, when the outer shell of the projectile is only slightly smaller in diameter than the caliber of the barrel.  Driving bands and obturators are used to seal these full-bore projectiles in the barrel because of manufacturing tolerances; there always exists some gap between the projectile outer diameter and the barrel inner diameter, usually a few thousandths of an inch; enough of a gap for high pressure gasses to slip by during firing.  Driving bands and obturator rings are made from material that will deform and seal the barrel as the projectile is forced from the chamber into the barrel.  Small caliber jacketed bullets do not normally employ driving bands or obturators because the jacket material, for example copper or gilding metal, is deformable enough to serve that function, and the bullet is made slightly larger than the barrel for that purpose, (see Full metal jacket bullet and driving band).  Sabots certainly use driving bands and obturators, because the same manufacturing tolerance issues exist when sealing the saboted projectile in the barrel, but the sabot itself is a more substantial structural component of the in-bore projectile configuration (Drysdale 1978).  Refer to the two APFSDS (Armor Piercing Fin Stabilized Discarding Sabot) pictures on the right to see the substantial material nature of a sabot to fill the bore diameter around the sub-caliber arrow-type flight projectile, compared to the very small gap sealed by a driving band or obturator to mitigate what is known classically as windage.  More detailed cutaways of the internal structural complexity of advanced APFSDS saboted long rod penetrator projectiles can be found at reference 2.

Chevrolet straight-6 engine: The Chevrolet inline 6 otto engine was Chevrolet's sole engine from 1929 (when it replaced their first 4-cylinder engine, the 171-cubic-inch four), through 1954, and was the base engine starting in 1955 when they added the small block V8 to the lineup.  It had finally been completely phased out by 1990 in North America, but in Brazil, GM held on to their fuel-injected version through the 1998 model year.  It was replaced by more recently developed V6 and four-cylinder engines.  Many popular cars and trucks, including the Chevrolet Camaro, Chevrolet Impala, and Chevrolet Suburban used the inline 6 as the base engine.  Chevrolet did not offer another inline 6 until the 2002 General Motors Atlas engine's debut in the Chevrolet TrailBlazer.

Gauge (bore diameter): The gauge of a firearm is a unit of measurement used to express the inner diameter (bore diameter) of the barrel.  Gauge is determined from the weight of a solid sphere of lead that will fit the bore of the firearm, and is expressed as the multiplicative inverse of the sphere's weight as a fraction of a pound, "e.g.", a one-twelfth pound ball fits a 12-gauge bore.  Thus there are twelve 12-gauge balls per pound, etc.  The term is related to the measurement of cannon, which were also measured by the weight of their iron round shot; an 8 pounder would fire an 8 lb (3.6 kg) ball.

Stroke ratio: In a reciprocating piston engine, the stroke ratio, defined by either bore/stroke ratio or stroke/bore ratio, is a term to describe the ratio between cylinder bore diameter and piston stroke.  This can be used for either an internal combustion engine, where the fuel is burned within the cylinders of the engine, or external combustion engine, such as a steam engine, where the combustion of the fuel takes place "outside" the working cylinders of the engine.

General Motors 122 engine: The 122 engine was designed by Chevrolet and was used in wide-array of General Motors vehicles.  The "122" was similar to the first two generations of the General Motors 60° V6 engine; sharing cylinder bore diameters and some parts .  The "122" was available in the US beginning in 1982 for the GM J platform compact cars and S-series trucks.

Supporting paragraphs: General Motors 122 engine General Motors 60° V6 engine
Answer: 122