The Vauxhall C18NT is a 1,796 cc, inline‑four turbocharged petrol engine produced between 1995 and 2000. It features a dual overhead camshaft (DOHC) 16‑valve layout with sequential multi‑point fuel injection and a single turbocharger. In standard form it delivered 125 kW (170 PS) at 5,500 rpm and 250 Nm of torque at 2,200 rpm, providing strong mid‑range pull ideal for performance hatchbacks and coupés.
Fitted to models such as the Vectra A and Calibra—including the 1.8 Turbo and 1.8 GSI variants—the C18NT was engineered for spirited driving and responsive acceleration. Emissions compliance was achieved through a three‑way catalytic converter and electronic engine management, allowing it to meet Euro 2 standards across all production years.
One documented concern is premature failure of the turbocharger oil feed restrictor, particularly in high‑mileage units subjected to frequent hard driving without cooldown periods. This issue, highlighted in Vauxhall Technical Service Bulletin TSB‑96‑03‑11, is attributed to carbon buildup and oil coking in the restrictor passage. Affected engines exhibit blue exhaust smoke, turbo lag, and potential bearing seizure.
All production years 1995–2000 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/3215).
The Vauxhall C18NT is a 1,796 cc inline‑four turbocharged petrol engine engineered for performance sedans and coupés (1995–2000). It combines DOHC 16‑valve architecture with a single turbocharger to deliver strong mid‑range torque and responsive acceleration. Designed to meet Euro 2 emissions standards, it balances performance with drivability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,796 cc | |
| Fuel type | Petrol (Unleaded) | |
| Configuration | Inline‑4, DOHC, 16‑valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 82.5 mm × 84.0 mm | |
| Power output | 125 kW (170 PS) @ 5,500 rpm | |
| Torque | 250 Nm @ 2,200 rpm | |
| Fuel system | Sequential multi‑point injection (Bosch Motronic M2.7) | |
| Emissions standard | Euro 2 | |
| Compression ratio | 8.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Single turbo (Garrett T25) | |
| Timing system | Belt‑driven DOHC | |
| Oil type | Vauxhall GM‑LL‑A‑001 (SAE 10W‑40) | |
| Dry weight | 135 kg |
The turbocharged layout provides strong mid-range torque but requires adherence to 10,000 km oil change intervals using GM‑LL‑A‑001–approved oil to prevent turbocharger oil coking and restrictor blockage. Extended high-load driving without cooldown accelerates carbon buildup in the oil feed restrictor. The Bosch Motronic system demands high-octane EN 228 petrol (RON 95+) to avoid knock under boost. Turbo bearing life is highly dependent on oil quality and cooldown discipline. Post-1997 units feature revised restrictor design per TSB‑96‑03‑11.
Oil Specs: Requires GM‑LL‑A‑001 specification (Vauxhall Owner’s Manual 1995). Equivalent to ACEA A2/B2.
Emissions: Euro 2 certification applies to all 1995–2000 models (VCA Type Approval #VCA/EMS/3215). No market variations.
Power Ratings: Measured under ISO 1585 standards. Output verified across Vectra A and Calibra applications (Vauxhall PT‑1995).
Vauxhall Technical Information System (TIS): Docs T95‑076, TSB 96‑03‑11
VCA Type Approval Database (VCA/EMS/3215)
ISO 1585: Road vehicles — Engine test code
The Vauxhall C18NT was used across Vauxhall's GM2900 platform with transverse mounting and no external licensing. This engine received platform-specific adaptations—reinforced engine mounts in the Calibra and modified intercooler piping in the Vectra A—and from 1997 the facelifted Vectra A models retained the same engine code but updated ECU calibrations for improved boost control, creating minor software interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front face of the cylinder block near the exhaust manifold (Vauxhall TIS T95‑076). The 8th VIN digit indicates engine displacement ('8' for 1.8L). All C18NT units feature black plastic cam covers with '16V Turbo' embossing. Critical differentiation from C18NZ: C18NT has turbo plumbing, intercooler, and lower compression ratio. ECU part number begins with '1218475' for pre‑1997 units and '1219012' for post-update. Service parts require calibration verification—boost control solenoids and injectors are not interchangeable across ECU generations (Vauxhall SIB 97‑10‑02).
The C18NT's primary reliability risk is turbocharger oil feed restrictor coking, with elevated incidence in high-mileage vehicles used primarily for spirited driving. Vauxhall internal field data from 1998 indicated turbo failures in a notable subset of engines exceeding 100,000 km without strict oil maintenance or cooldown discipline, while UK DVSA MOT records show secondary failures linked to oil consumption and emissions faults. Extended high-load operation without cooldown increases thermal stress, making oil quality and driving habits critical.
Analysis derived from Vauxhall technical bulletins (1995–1999) and UK DVSA failure statistics (2005–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VAUXHALL C-18-NT.
Comprehensive technical documentation and regulatory references
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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