GM Vortec engine

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X25XE
ManufacturerGeneral Motors Europe
TypeV6 petrol engine
PredecessorC25XE
SuccessorY26SE
Bore81.6 mm (3.213 in)
Stroke79.6 mm (3.134 in)
Displacement2.5 L (2498 cc, 152.4 cu in)
Block alloycast iron
Head alloyaluminium alloy
Valvetrain2x DOHC
Fuel typeunleaded petrol
Oil systemwet sump
Cooling systemwater/antifreeze
Power output125 kilowatts (168 hp)
Torque output227 N·m (167 lb·ft)
Compression ratio10.8:1
X30XE
ManufacturerGeneral Motors Europe
TypeV6 petrol engine
SuccessorY32SE
Bore86 mm (3.386 in)
Stroke85 mm (3.346 in)
Displacement3 L (2960 cc, 180.6 cu in)
Block alloycast iron
Head alloyaluminium alloy
Valvetrain2x DOHC
Fuel typeunleaded petrol
Oil systemwet sump
Cooling systemwater/antifreeze
Power output155 kilowatts (208 hp)
Torque output270 N·m (199 lb·ft)
Compression ratio10.8:1

The X25XE is a General Motors Europe (GM) petrol engine. It is a 2498 cc (2.5L) 24 valve, DOHC V6 engine, producing, in standard form 125 kilowatts (168 hp) (170 PS).

The breakdown of the engine name [1] is as follows:

X - Exhaust Emissions Level: 94/12/EC, stage 2
25 - 2.5 Litre displacement
X - Compression Ratio - 10.0-11.5:1
E - Mixture System - Injection

In the early 1990s, GM identified the need for a modern, lightweight and compact power plant to replace its ageing straight-6 engine range. This engine needed to be compact, to allow its use in front-wheel drive applications, as well as rear-wheel drive cars.

The first version arrived in the Opel Vectra / Vauxhall Cavalier (both codenamed "Vectra-A") and Opel/Vauxhall Calibra in the C25XE form, and was later followed by the X25XE in the Opel/Vauxhall Omega and Vectra-B, with the Omega gaining a variant with increased displacement in the form of the X30XE.

This power plant was a modern 4 valve per cylinder, quad cam arrangement, with an oil to water heat exchanger mounted within the V of the engine block. The cylinder heads were constructed from aluminium alloy, and the block from cast iron.

An unusual feature of the engine was its 54 degree cylinder angle, as opposed to the more conventional 60 degree setup used on many V6 units, this added to the setups' compactness.

A Bosch Motronic engine management system is used to control the unit, with full sequential fuel injection, knock control on each bank, distributorless ignition system (DIS), and closed loop lambda control.

Technical data

Engine X25XE
configuration V6 petrol engine
displacement (cc) 2498
bore (mm) 81.6 mm (3.213 in)
stroke (mm) 79.6 mm (3.134 in)
max power kW @rpm 125 kilowatts (168 hp) @ 6000
max torque Nm @rpm 227 N·m (167 lb·ft) @ 3200
compression ratio 10.8:1
engine management Bosch Motronic M2.8.1 then M2.8.3 in 2000 approx
idle speed 450-1030
max rpm 6600
firing order 1-2-3-4-5-6
Engine X30XE
configuration V6 petrol engine
displacement (cc) 2960
bore (mm) 86 mm (3.386 in)
stroke (mm) 85 mm (3.346 in)
max power kW @rpm 155 kilowatts (208 hp) @ 6000
max torque Nm @rpm 270 N·m (199 lb·ft) @ 3400
compression ratio 10.8:1
engine management Bosch Motronic M2.8.1 then M2.8.3 in 2000 approx
idle speed 450-1030
max rpm 6600
firing order 1-2-3-4-5-6

The "X" variant of the engine had the addition of secondary air injection, and EGR to meet later and more stringent emission requirements.

The air injection blew air via a large blower into the exhaust manifolds to ignite un-burnt fuel in the downpipes during the engine warm up phase, in order to get the catalytic converters up to temperature faster. The EGR setup re-cycled exhaust gases (which are in theory inert to the combustion cycle) in order to reduce the production of NOx.

History

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.

2000 saw a complete revision of the power plant in order to meet increasing emission requirements, with the 2.5 and 3.0 being replaced by lower compression 2.6 (Y26SE) and 3.2 (Y32SE) units.

These later power plants had a revised engine management system setup, which utilised 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.

References

  1. Topbuzz, "Engine Codes Explained", Topbuzz Website, 2002. Accessed 9 Dec 2006 [1]