The Opel Z12XEP is a 1.2 l (1,229 cc, 75.0 cu-in) straight-four 4-stroke natural aspirated gasoline small-displacement engine from the second generation of the GM Family O Ecotec engines, developed by Opel, at the time a subsidiary of General Motors. The engine was manufactured since 2002.
The Opel Z12XEP engine uses a light-weight cast-iron engine block with a cast-iron crankshaft and aluminum head with dual chain-driven overhead camshafts (DOHC) and four valves per cylinder (16 valves in total). It is an updated version of the Z12XE engine and features TwinPort technology – twin intake ports with a choke closing one of the ports at low RPM, providing strong air swirl pattern for higher torque levels and better fuel economy. The crankshaft and oil galleries were also redesigned. The engine used ECU Bosch ME7.6.1 or Bosch ME7.6.2.
It has a 73.4 mm (2.89 in) cylinder bore and 72.6 mm (2.86 in) piston stroke. Compression ratio rating is 10.5:1. The Z12XEP engine produces 80 PS (59 kW; 79 HP) at 5,600 rpm of maximum horsepower and 110 Nm (11.2 kg·m; 81.2 ft·lb) at 4,000 rpm of peak torque.
The breakdown of the engine code is as follows:
- Z – Euro 4 engine
- 12 – 1.2 Liter displacement
- X – Comression ratio from 10 to 11.5:1
- E – Multi Point Fuel Injection system
- P – Increased power
General information
| Engine Specifications | |
| Engine code | Opel Z12XEP |
| Layout | Four stroke, Inline-4 (Straight-4) |
| Fuel type | Gasoline (petrol) |
| Production | 2002- |
| Displacement | 1.2 L, 1,229 cm3 (75.0 cu in) |
| Fuel system | Multipoint fuel injection (MFI) |
| Power adder | None |
| Power output | 80 PS (59 kW; 79 HP) at 5,600 rpm |
| Torque output | 110 Nm (11.2 kg·m; 81.2 ft·lb) at 4,000 rpm |
| Firing order | 1-3-4-2 |
| Dimensions (L x W x H): | – |
| Weight | – |
Cylinder block
The engine used a cast-iron cylinder block and a cast-iron crankshaft five-bearings supported system. Bore and stroke are 73.4 mm (2.89 in) and 72.6 mm (2.86 in). Compression ratio rating is 10.5:1.
| Cylinder block | ||
| Cylinder block alloy | Cast-iron | |
| Compression ratio: | 10.5:1 | |
| Cylinder bore: | 73.4 mm (2.89 in) | |
| Piston stroke: | 72.6 mm (2.86 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
Cylinder head
The cylinder head is made of an aluminum alloy. The Z12XEP engine has chain-driven dual overhead camshafts with TwinPort technology. Valves are actuated via roller finger followers with hydraulic tappets.
| Cylinder head | ||
| Cylinder head alloy: | Aluminium | |
| Valve Arrangement: | DOHC, chain-driven | |
| Valves: | 16 (4 valves per cylinder) | |
| Valve timing: | INTAKE | – |
| EXHAUST | – | |
| Valve head diameter: | INTAKE | 27.90-28.10 mm (1.0984-1.1062 in) |
| EXHAUST | 24.90-25.10 mm (0.9803-0.9880 in) | |
Head tightening procedure and torque specs:
- Step 1: 25 Nm (2.5 kg·m, 18.4 ft·lb)
- Step 2: Turn all bolts 60°
- Step 3: Turn all bolts 60°
- Step 4: Turn all bolts 60°
Maintenance data
| Oil system | |
| Oil consumption , L/1000 km (qt. per miles) | up to 0.5 (1 qt. per 1200 miles) |
| Recommended engine oil | 5W-30, 5W-40, 10W-30, 10W-40 |
| Oil type |
API SG / CD CCMC G4 / G5 |
| Engine oil capacity (Refill capacity) | With filter change 3.5 l |
| Oil change interval, km (miles) | 30,000 (18,000) |
| Ignition system | |
| Spark plug | Bosch FQR8LEU2 |
| Spark plug gap | 0.85-0.95 mm (0.0334-0.0374 in) |
| Spark plug tightening torque | 25 Nm (2.55 kg·m; 18.45 ft·lb) |
Vehicle applications
| Model | Years Produced |
| Opel / Vauxhall Agila A 1.2 16v | 2004-2007 |
| Opel / Vauxhall Corsa C 1.2 16v | 2004-2006 |
| Opel / Vauxhall Corsa D 1.2 16v | 2006-2014 |
Author:
After adjusting the engine model z12xep we are having an ACCELERATION problem. Can you please advise. Thank you.
Check ignition coil and spark plugs. Use only original Bosch (German) parts for long time best performance. This is personal experience.