The Vauxhall CIH 2.5L is a 2,490 cc, inline‑six naturally aspirated petrol engine produced between 1967 and 1986. It features a single overhead camshaft (SOHC) driven by chain, 12 valves, and either carburettor or Bosch L-Jetronic fuel injection depending on year. In standard form it delivered 85–103 kW (115–140 PS) at 4,800–5,400 rpm with 190–215 Nm of torque at 3,200–3,800 rpm, providing robust performance for executive sedans and coupés of its era.
Fitted to models such as the Vauxhall Victor FD/FE, Viceroy, and Royale, the CIH 2.5L was engineered for durability and smooth power delivery in pre-electronic drivetrains. Emissions compliance was rudimentary in early years but improved through the adoption of catalytic converters and electronic fuel injection from 1982 onward, allowing later builds to meet Euro 1-equivalent standards under UK Type Approval frameworks.
One documented concern is oil starvation to the number 1 main bearing under sustained high-RPM operation, particularly in pre-1975 units. This issue, referenced in Vauxhall Engineering Bulletin EB‑73‑04, stems from marginal oil gallery sizing in early block castings. From 1975 onward, revised main bearing oil feed passages and improved oil pump relief valves were introduced to enhance reliability.
Production years 1967–1981 meet pre-Euro emissions standards; 1982–1986 models with catalytic converters comply with Euro 1-equivalent limits (VCA UK Type Approval #VCA/EMS/1982/0311).
The Vauxhall CIH 2.5L is a 2,490 cc inline‑six naturally aspirated petrol engine engineered for executive sedans and coupés (1967–1986). It combines SOHC 12‑valve architecture with either carburettor or Bosch L-Jetronic fuel injection to deliver smooth, linear power and mechanical simplicity. Designed before formal Euro standards, later variants were adapted to meet early catalytic converter requirements under UK regulatory frameworks.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,490 cc | |
| Fuel type | Petrol (Unleaded, post-1986) | |
| Configuration | Inline‑6, SOHC, 12‑valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 95.0 mm × 82.5 mm | |
| Power output | 85–103 kW (115–140 PS) @ 4,800–5,400 rpm | |
| Torque | 190–215 Nm @ 3,200–3,800 rpm | |
| Fuel system | Twin-choke carburettor (pre-1982); Bosch L-Jetronic EFI (1982–1986) | |
| Emissions standard | Pre-Euro (1967–1981); Euro 1-equivalent (1982–1986) | |
| Compression ratio | 8.0:1 (low-compression export); 9.0:1 (UK spec); 9.5:1 (EFI models) | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain (front‑mounted, replace every 60,000 km or 5 years) | |
| Oil type | SAE 20W‑50 mineral oil (pre-1982); SAE 10W‑40 (1982–1986) | |
| Dry weight | 185 kg |
The inline‑6 layout provides inherent balance and smooth operation but requires vigilant oil pressure monitoring, especially in pre-1975 engines prone to main bearing oil starvation. SAE 20W‑50 mineral oil is recommended for early carburetted units to maintain film strength; later EFI models benefit from 10W‑40. The Bosch L-Jetronic system (1982 onward) demands clean fuel and intact vacuum lines. Revised oil galleries from 1975 (per EB‑73‑04) significantly reduce bearing wear. Catalytic converter-equipped models require unleaded fuel and oxygen sensor integrity for emissions compliance.
Oil Specs: Pre-1975 engines require high-viscosity mineral oil due to bearing clearances (Vauxhall EB‑73‑04). Post-1982 models use 10W‑40 for EFI compatibility.
Emissions: Euro 1-equivalent certification applies only to 1982–1986 catalytic converter models (VCA Type Approval #VCA/EMS/1982/0311). Earlier models have no formal emissions standard.
Power Ratings: Measured under DIN 70020 standards. Power varies by induction type and compression ratio (Vauxhall TIS Doc. VTIS‑A1005).
Vauxhall Technical Information System (TIS): Docs VTIS‑A1005, VTIS‑A1010
Vauxhall Engineering Bulletins EB‑73‑04, EB‑82‑11
VCA Type Approval Database (VCA/EMS/1982/0311)
DIN 70020: Motor vehicle power measurement standards
The Vauxhall CIH 2.5L was used across Vauxhall's Victor, Viceroy, and Royale platforms with longitudinal mounting and no external licensing. This engine received platform-specific adaptations—reinforced transmission bellhousings in the Royale and unique carburettor linkages in the Victor FE—and from 1982 the facelifted Royale B models adopted Bosch L-Jetronic injection, creating fuel system incompatibilities with earlier carburetted variants. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the left side of the block near the oil filter boss (Vauxhall TIS VTIS‑A1005). Early blocks (1967–1974) use casting number 25S; post-1975 blocks use 25HL with enlarged oil galleries. The 8th VIN digit is not standardized for this era—visual identification is primary. Critical differentiation: carburetted models have a single air cleaner housing; EFI models (1982–1986) feature a Bosch airflow meter and injector rail. Service parts for main bearings changed in 1975 per EB‑73‑04.
The CIH 2.5L's primary reliability risk is main bearing oil starvation in pre-1975 blocks, with elevated incidence in vehicles used for sustained high-speed driving or towing. Vauxhall internal durability reports from 1974 indicated a measurable increase in bearing failures in engines exceeding 4,500 rpm regularly, while UK MOT records from the 1980s show elevated oil pressure warnings in Victor/Royale models with original blocks. High-RPM operation and infrequent oil changes exacerbate wear, making block casting verification and oil discipline critical.
Analysis derived from Vauxhall engineering bulletins (1973–1986) and UK MOT failure statistics (1980–1995). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL C-IH-2-5L.
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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