General Motors' Opel subsidiary in Europe designed a compact V6 engine with an unusual 54° vee angle. It was an iron block/aluminum head DOHC design with 4 valves per cylinder. All 54° engines were assembled at Ellesmere Port in England. History In the early 1990s, Opel identified the need for a modern, lightweight and compact power plant to replace its aging straight-six engine range. These engines have a cast iron engine block with cast aluminium alloy cylinder heads. The cylinder heads contain 4 valves per cylinder actuated by dual overhead camshafts which are driven by a timing belt. These engines however, differed from many modern V6 engines in that it has a 54 degree cylinder bank angle; as opposed to the more conventional 60 degree setup. This added to the engines' compactness which was needed to allow its use in front-wheel drive applications, as well as rear-wheel drive cars. Other features of these engines include: an oil to water heat exchanger is mounted within the V of the engine block, Bosch Motronic engine management system with full sequential fuel injection, knock control on each bank, Distributorless Ignition System (DIS), and closed loop lambda control. Minor changes were made to the unit during its production, including an uprated oil pump around mid-1997, with the addition of larger oilways in the head machining (T-Vents), and modified valve lifters to reduce top-end valve noise, at which point the cam belt arrangement also changed with the lower idler moving. Around 1998, the spin-on metal canister oil filter was changed to a disposable paper element. Revision The engine was reworked substantially in 2000 in order to meet increasing emission requirements; with the 2.5 and 3.0 being replaced by lower compression 2.6 and 3.2 units. While displacement was changed the bore centers and deck height were retained. These later power plants had a revised engine management system setup, which used quad lambda sensor control, coil per plug ignition system and drive by wire throttles. The 3.2 also received a stronger steel crankshaft. As a result of these changes the EGR and secondary air injection system were removed. Recalls In its 3.0 L form, this engine was notable for recalls of all units installed in Cadillac Cateras due to timing belt tensioner bearing failures, which could cause catastrophic damage to the engine because of its interference design. 2.5 The C25XE or B258I has an bore and stroke