The Circle L is an automobile engine produced by GM Powertrain Poland in Poland. It is a inline-four 16-valve turbocharged diesel engine originally designed by Isuzu but now owned by General Motors. The engine is produced in Europe by General Motors for use in the Opel, Vauxhall and Chevrolet vehicles and by Honda for use in the Civic compact car. History In the late nineties the Japanese company Isuzu, which was known for the efficiency of its diesel engines, collaborated with General Motors on a new diesel engine for the European market for Opel and Vauxhall. For this purpose it opened a new plant in the city of Tychy, in Poland, called Isuzu Motor Polska. Characteristics For reasons of economy, GM and Isuzu chose not to make an engine from scratch, but rather evolved the new engine from an existing base. Thus, the Isuzu 4EE1 1.7-liter was chosen and developed into the "Circle L" family of engines, also known as the 4EE2. The engine kept the same dimensions of 1.7 4EE1. The main differences are in the DOHC camshafts and direct injection. The first engines mounted a simple direct injection and met the Euro 3 standard, while the later engines met Euro 4 and used common rail injection technology. The 1.7 Circle L common rail engines were the first common rail engines used in Opels. 60 percent of the components for the production of the engines at Isuzu Motor Polska come from Germany, as well as the aluminium alloy for the manufacture of the cylinder head. The Polish plant was responsible for the construction and the development of the valvetrain. The block, however, comes to Tychy already built by the Isuzu factory in Hokkaido, Japan. These engines are particularly important for Opel since they are fitted to their best-selling models in a period in which diesel engines became extremely popular. Moreover, thanks to their great fuel economy and reduced emissions, Circle L engines were integrated into the family of Ecotec engines. Later Circle L engines became part of the Ecoflex family. The 1.7-liter 4EE2 was offered in six variants, whose characteristics and applications are described below. Y17DT The abbreviation Y17DT identifies the very first Circle L engine: As already mentioned it is a Euro 3 engine with a compression ratio of 18.4:1. The unit has Denso engine management, as in most Circle L engines. A Mitsubishi TD025 turbocharger is fitted,