Rover K-series engine

The cylinder block of a United Kingdom Rover K-series 16-valve DOHC engine with damp liner cylinders

The K series was introduced in 1988 by Rover Group as a powerplant for the Rover 200 car. It was the second volume-production implementation of the low-pressure sand-casting (or LPS) technique in a new plant sited between East Works and Cofton Hackett. (The first volume application of the LPS process had been for the M-16 cylinder head, produced in South Works, adjacent to the former forge). The LPS process pumped liquid aluminium into a chemically-bonded sand mould from below. This reduced oxide inclusions and gave a casting yield of around 90%, compared with 60% for more conventional gravity casting processes. The process avoided many of the inherent problems of casting aluminium components and consequently permitted lower casting wall thickness and higher strength-to-weight ratios. However, the process required the use of heat-treated LM25 material which gave the engines a reputation for being fragile. An engine overheat would often result in the material becoming annealed and rendering the components scrap. The layout of the engine bay on some Rover cars fitted with K-series engines – particularly the MGF with its mid-engined layout – means that a commonly-occurring coolant leak under the inlet manifold can go undetected until severe damage has been done to the head. The aluminium engine blocks were fitted with spun-cast iron cylinder liners that were initially manufactured by GKN's Sheepbridge Stokes of Chesterfield, but these were replaced by liners made by Goetze. Unfortunately a large number of aftermarket engines, the so-called "VHPDs", were built with the old substandard GKN liners by Minister, Lotus and PTP well after the introduction of the Goetze liners to production in 2000.

The engine was introduced initially in 1.1-litre single overhead cam and 1.4-litre dual overhead cam versions. Because Honda stopped providing Rover with engines after the end of their relationship, but well before the BMW takeover, an enlargement of the K Series design to 1.6 and 1.8 litres was carried out. This was done by using larger diameter cylinder liners and also increasing the stroke. The change required a block redesign with the removal of the cylinder block's top deck and a change from "wet" liners to "damp" liners.[1] The plastic throttle body fitted to the engine until 2001 was manufactured by the SU Carburettor company. They also included aluminium and larger sized bodies.

The four-cylinder engines were held together as a sandwich of components by long through-bolts which held the engine under compression, though this construction is not unknown, and was used in early lightweight fighter engines from the First World War. It had also been used in motorcycle engines and Triumph Car's "Sabrina" race engine.

The two types of head that were bolted to the common four-cylinder block were designated K8 (8 valves) and K16 (16 valves). A later head design also incorporated a Rover-designed Variable Valve Control (VVC) unit (derived from an expired AP patent). This allowed more power to be developed without compromising low-speed torque and flexibility. The VVC system constantly alters the inlet cam period, resulting in a remarkably flexible drive: the torque curve of a VVC K-series engine is virtually flat throughout the rev range and power climbs steadily with no fall-off whatsoever until the rev limiter kicks in at 7,200 rpm.

Following the collapse of MG Rover in 2005, the K Series engine started a new and rather interesting chapter in its history. Two separate re-developments of the engine were taking place by at the time two rival Chinese car firms.

The Chinese automaker Nanjing Automobile (NAC) purchased the assets of MG Rover and in doing so acquired use of the Longbridge plant and the intellectual property rights and production tooling to many designs, including those of the K series engine.

With the help of Lotus Engineering, NAC went on to produce the N Series an improved version of the K Series with redesigned headgasket and oil rail built on the original tooling.

This engine featured in the relaunched MG TF in the UK and the MG3 SW and MG7 in China. Contrary to popular belief, the N Series was never fitted to the MG 6.

When the MG TF ceased production for the final time in 2011, so did the N Series.

The second development was by the larger Chinese conglomerate SAIC Motor. SAIC had also previously purchased the rights and blueprints to several of MG Rovers designs. Whilst they had the necessary knowhow they didn't have any tooling so had to essentially reverse engineer their version of the engine.

The advantage of this was it allowed Ricardo 2010, the company tasked by SAIC to carry out development the opportunity to improve the engine in a number of areas.

The main areas of improvement included the head being redesigned to improve the waterways and structural rigidity and the block was also strengthened.

All new tooling was used in its production and the quality of materials and that of the aluminium casting process created a much more substantial update than that of the N Series.

This new engine would go on to power the Roewe 750, the Roewe 550 and later after the two firms NAC and SAIC merged, The MG 6.

The SAIC Kavachi engine is an extensively improved version of the Rover K series, using a different turbo and gearbox, improved head gasket and strengthened block. UK engineering firm Ricardo plc, expert in race engine designs, was commissioned to not only redesign the engine but also the manufacturing process to produce what is now a very reliable engine. It is only available in 1.8 L; 109.6 cu in (1,796 cc) version.

• Austin Memories – History of Austin and Longbridge
• K-Series engine history – The full history of this engine

• Engine Overhaul Manual. Rover K Series. MG Rover Group.
• Hammill, Des (2008). The Rover K-series 16V Engine. 1989-2005. CP Press. ISBN 978-1-84155-688-8.