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 su…
Production years 1967–1981 meet pre-Euro emissions standards; 1982–1986 models with catalytic converters comply with Euro 1-equivalent limits .
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 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.
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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.
The most common questions about engine codes, what they mean, how to find them and how this database works
The CIH 2.5L offers robust mechanical design and smooth operation, but pre-1975 examples are prone to main bearing oil starvation under high-RPM use. Later models (1975–1986) benefit from improved oil galleries and EFI. With regular oil changes and RPM discipline, the engine can reliably exceed 200,000 km.
Top issues include main bearing oil starvation (pre-1975), carburettor leaks, timing chain stretch, and cylinder head coolant jacket corrosion. These are documented in Vauxhall Engineering Bulletins EB‑73‑04 and EB‑82‑11 and supported by historical MOT data.
The CIH 2.5L was used in the Victor FD/FE (1967–1976), Viceroy (1976–1978), Royale A (1978–1982), and Royale B (1982–1986). It was not used in Cavalier, Chevette, or smaller models, which used four-cylinder engines.
Yes. Common upgrades include triple Weber carburettors (+15–20 kW), performance camshafts, and ported heads. EFI models can be remapped for modest gains. However, the SOHC valvetrain limits high-RPM potential compared to DOHC designs.
Real-world consumption averages 12–14 L/100km (24–20 mpg UK) in mixed driving. Highway cruising can achieve 10 L/100km (28 mpg UK), while city driving may exceed 16 L/100km. Economy is typical for a 1970s inline‑6 petrol engine.
No. The CIH 2.5L is a non-interference engine. If the timing chain fails, the pistons will not contact the valves, preventing catastrophic damage—though the engine will stop running.
Pre-1982 carburetted models require SAE 20W‑50 mineral oil for bearing protection. 1982–1986 EFI models use SAE 10W‑40. Change every 8,000 km or 12 months, especially with high-RPM use.
Comprehensive technical documentation and regulatory references
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EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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