The Audi ACK is a 2,798 cc, V6 petrol engine produced between 1995 and 2000. It features a 30 — valve configuration with three valves per cylinder (two intake, one exhaust), double overhead camshafts (DOHC), and sequential multi — point fuel injection. In standard tune it produces 123 kW (167 PS) at 5,800 rpm with 240 Nm of torque, providing smooth power delivery and refined operation.
Fitted to platforms including the Audi A4 (B5) and Audi A6 (C4), the ACK engine was engineere…
All ACK engines comply with Euro 2 emissions standards (EU Directive 94/12/EC,.
The Audi ACK is a 2,798 cc V6 petrol engine engineered for mid-size and executive applications (1995–2000). It combines a 30-valve head design with sequential MPI to deliver smooth power delivery and strong mid-range performance. Designed to meet Euro 2 emissions standards, it balances refinement with drivability.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,798 cc | |
Fuel type | Petrol | |
Configuration | V6, DOHC, 30-valve | |
Aspiration | Naturally aspirated | |
Bore × stroke | 84.5 mm × 83.0 mm | |
Power output | 123 kW (167 PS) @ 5,800 rpm | |
Torque | 240 Nm @ 3,200 rpm | |
Fuel system | Sequential multi-point fuel injection (MPI) | |
Emissions standard | Euro 2 | |
Compression ratio | 10.5:1 | |
Cooling system | Water-cooled | |
Turbocharger | Not applicable | |
Timing system | Dual-row timing belt | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | 168 kg |
The Audi ACK was used across Audi's B5/C4 platforms with longitudinal mounting and no licensed applications. This engine received platform-specific adaptations-reinforced mounts in the A6 and revised cooling routing in the A4-and from 1998 the facelifted A4 B5.5 models adopted updated ECU calibrations, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Engine Finders UK Ltd, which operates EngineCode.uk, can pass your enquiry to engine suppliers in the UK. The service is for vehicles in the United Kingdom, with UK delivery or fitting. This is a commercially connected service, and sending an enquiry does not confirm diagnosis or compatibility.
Diagnostic reminder: If a technician has recommended replacing the engine, you can send an enquiry to engine suppliers in the UK. Confirm the diagnosis first: an engine-code record does not diagnose a fault.
Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from manufacturer technical service bulletins and industry workshop records. 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 Audi ACK offers smooth performance and refinement, but older units (1995–1997) are prone to timing belt tensioner wear. Later revisions (post-1998) improved durability with updated components. When maintained properly—especially with timely timing belt changes and use of quality oil—these engines can reliably exceed 150,000 km.
Key issues include timing belt tensioner wear affecting cam timing, intake valve carbon buildup leading to misfires, catalytic converter failure due to short trips, and oil leaks from the valve cover gasket. These are documented in Audi service bulletins and supported by field service data.
The ACK engine was used in the Audi A4 (B5, 1995–2000) and Audi A6 (C4, 1995–1997). It was offered as the 2.8 V6 variant, meeting Euro 2 emissions standards. It served as the mid-range petrol engine for executive trims during this period.
Aftermarket ECU tuning is common on the ACK platform, but increasing boost or altering engine parameters accelerates component wear, impacts emissions compliance, and may void vehicle warranties. Any modifications should be evaluated carefully by a qualified specialist.
In combined driving, the ACK achieves approximately 10.5–12.0 L/100 km (27–24 mpg UK). Highway efficiency improves to ~8.5 L/100 km (~33 mpg UK), while city driving may reach 13.0 L/100 km (~22 mpg UK). Real-world economy depends on driving style and condition.
Yes. The ACK is an interference engine, meaning that if the timing belt fails, the pistons can strike the open valves, resulting in severe internal damage. This makes timely inspection and replacement of the timing belt critical, especially on high-mileage or overdue units.
Audi specifies SAE 10W-40 oil meeting API SL standards. Use high-quality mineral or semi-synthetic oil designed for older petrol engines and change it every 15,000 km or annually to ensure proper lubrication of the valvetrain and timing components.
Comprehensive technical documentation and regulatory references
EngineCode.uk is operated by Engine Finders UK Ltd. It provides engine-reference information and an optional commercial enquiry service. It is not an official manufacturer website. Check the record's sources and confirm vehicle-specific details before relying on it for parts, repairs or replacement.
Our editorial standard prioritises relevant manufacturer documentation and official regulatory sources. The sources and verification status for a record should be checked alongside the data.
A statement is not verified merely because a source is listed. Where supporting evidence is missing or conflicting, the record should identify that limitation. Please report unsupported or inconsistent information.
Transparency in gaps
A missing or unverified value does not mean the manufacturer has withheld it. We distinguish information not yet verified, information not available to us, and information explicitly not disclosed by the source.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
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.
Records are subject to review and correction. Source links, dates and verification notes should be read with the technical information. Our Editorial and Sourcing Policy explains our standards and review process.
Found an error or missing source? Report a problem with this page. Include the field or statement concerned and a supporting source if available. You can also email corrections@enginecode.uk.
Copyright and permissions
Images and other material may be protected by copyright. Attribution does not by itself grant permission to reuse material. If you believe material on this site infringes your rights, contact copyrights@enginecode.uk with the page URL and details of your claim. We will review the material and take appropriate action.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
Our Privacy Policy explains how Engine Finders UK Ltd uses information from visits, vehicle lookups, enquiries and messages. Our Cookie Policy explains cookies and similar technologies and how to change your choices.
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
Ownership and commercial services
EngineCode.uk is owned and operated by Engine Finders UK Ltd. Alongside our reference content, we offer an optional replacement-engine enquiry service through Engine Finders and may identify relevant services provided by businesses connected with us. These commercial connections are disclosed. Using an enquiry service is not required to read our reference content.
Engine Finders UK Ltd operates this website. Our optional enquiry service has a commercial purpose. Our Ownership and Commercial Disclosure explains the relationship between the reference website and that service. Participating suppliers pay a fee or subscription to participate on the network and receive quote requests.
Use this record as a starting point for identification. Specifications and vehicle applications may contain errors or omissions. Confirm the exact engine variant and compatibility using vehicle-specific documentation and a qualified supplier or technician.
All external links open in new tabs. Please verify current availability of resources.