The GM High Feature engine (also known as the HFV6, and including the 3600 LY7 and derivative LP1) is a family of modern General Motors DOHC V6 engines. The series was introduced in 2004 with the Cadillac CTS and the Holden Commodore (VZ). It is a 60° 24-valve design with aluminum block and heads and sequential multi-port fuel injection. Most versions feature continuously variable cam phasing on both intake and exhaust valves and electronic throttle control. Other features include piston oil-jet capability, forged and fillet rolled crankshaft, sinter forged connecting rods, a variable-length intake manifold, twin knock control sensors and coil-on-plug ignition. It was developed by the same international team responsible for the Ecotec, including the Opel engineers responsible for the 54° V6, with involvement with design and development engineering from Ricardo plc. Holden sold a HFV6 engine under the name Alloytec. The High Feature moniker on the Holden produced engine is reserved for the twin cam phasing high output version. The block was designed to be expandable from 2.8 L to 4.0 L. High Feature V6 engines were previously produced in Fishermans Bend, Port Melbourne, Australia and remain in production at the following four manufacturing locations: St. Catharines Engine Plant, St. Catharines, Canada; Flint Engine South in Flint, Michigan, United States; Romulus Engine Plant in Romulus, MI and Ramos Arizpe, Coahuila, Mexico. The assembly lines for the St. Catharines and Flint facilities were manufactured by Hirata Corporation at their powertrain facility in Kumamoto, Japan. Most of the designs of this motor happened in Flint. They were first produced for the Cadillac range. The engine block and cylinder heads are cast at Defiance Foundry in Defiance, Ohio. History The HFV6 was first designed, tested and produced in a joint program by Cadillac and Holden. A majority of designs into the new alloy construction, transmission pairing and first use in production were all undertaken in Detroit (and manufactured in St. Catharines, Ontario). Holden had the job of developing smaller engines (Holden 3.2, LP1 and Saab 2.8, LP9 Turbo) as well as their own Holden 3.6 HFV6 (called the Alloytec V6) for local models. Cadillac and Holden both tested variations of these engines in the United States and Australia. 2.8 LP1 A LP1 variant was introduced in the 2005 Cadillac CTS. It was also used on the Chinese 2008 CTS. It has a bore and stroke, sequential multi-port fuel injection and a