The K-Series engine is a series of engines built by Powertrain Ltd, a sister company of MG Rover. The engine was built in two forms: a straight-four cylinder, available with SOHC and DOHC, ranging from 1.1 L to 1.8 L; and the KV6 V6 variation.
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The K-Series was introduced in 1988 by Rover Group as a powerplant for the Rover 200 car. It was revolutionary in that it was the first volume production implementation of the low pressure sand casting technique. This works by injecting liquid aluminium into an upturned sand mould from below. In this way any oxide film always remains on the surface of the casting and is not stirred into the casting structure. This production technology overcame 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 aluminium engine blocks were fitted with spun cast iron cylinder liners that were initially manufactured by GKN's Sheepbridge Stokes of Chesterfield, but replaced by spun cast iron liners made by Goetze after some seminal research conducted by Charles Bernstein at Longbridge, which proved influential even to Ducati for their race engines. Unfortunately a large number of aftermarket engines, the so-called "VHPD"s" were built with the old substandard GKNs by Minister, Lotus and PTP well after the Goetze liner's introduction to the production line in 2000.
The engine was introduced initially in 1.1 L single overhead cam and 1.4 L dual overhead cam versions. The 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 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. As the Honda engines became obsolescent and were phased out, 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. 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 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.
By comparison, the V6 engines are more conventional engines that do not make use of the through bolts to hold the head to the block.
The K-Series engine has gained a reputation for head gasket trouble. This is due to a range of problems, including build tolerances, reduced block face stiffness, casting quality and material and cooling system layout. A number of changes were made over the years to improve the condition.
Amongst the first of the changes was the introduction of steel head locating dowels. Early versions of the K Series engine had steel dowels, but these were loose fitting and used as an assembly aid. Plastic dowels were then introduced to prevent head face damage on the assembly line and also as a cost saving. This engine had wet liners and a solid block top deck and was not known for being prone to gasket failure. The plastic dowels were carried forward to the redesigned K series which was then available in 1600 and 1800 capacities by using damp liners and an open block design. However, it became apparent that this engine had an issue with head gasket failure, which was partly due to lack of stiffness in the head/block interface. To help reduce this shuffling, steel dowels were reintroduced, but with a tight fit to fix the head securely to the block face. This reduced one mode of head gasket failure caused by movement between the block and head faces, but was only partly successful, because the dowels only helped in their local areas. The gasket itself was also subject to minor improvements to the sealing bead design over the years.
During its later years, the cooling system of some models was also modified by the introduction of a PRT (pressure-release thermostat). This allowed increased coolant flow at high engine loads, even before high temperatures were reached, and reduced the thermal shock the engine saw when a conventional thermostat was first opened. This thermal shock would cause differential expansion across the gasket face, causing relative movement between head and block.
A new design of head gasket has been available for several years from Land Rover which can be retro-fitted to all K-Series engines. This is of the MLS (multi layer steel) design. This has now been superseded by a new MLS design that is used in conjunction with higher tensile head bolts and strengthened oil rail (into which the bolts are screwed). A modified tightening method is also used with the new bolts. The effectiveness is yet to be proved.
Destined to be introduced with the Euro IV emissions compliant engine in late 2005 was the MLS gasket and strengthened oil rail. The aim of the latter is to improve engine rigidity. But this was never introduced by MG Rover Group, as the company had gone bankrupt by the time of the planned launch.
The N-Series engine (basically the aforementioned Euro IV-compliant K-Series) in the MG TF relaunched by Nanjing Automotive in September 2008, has these modifications as standard.
Early K8 engines used a single SU KIF carburetter with a manual choke and a breaker-less distributor mounted on the end of the camshaft. MEMS Single point injection became standard with the launch of the Rover 100 in 1994.
K16 models used MEMS electronic engine management in either Single Point or Multi Point forms, with a single coil on the back of the engine block and a distributor cap and rotor arm on the end of the inlet camshaft. MEMS 2J was used on the VVC engine, to control the Variable Valve Control and also the distributorless ignition system, which was necessary thanks to having camshaft drive belts at both ends of the engine. With the launch of the Rover 25 and Rover 45 in 1999, MEMS 3 was introduced, with twin coils and sequential injection.
Early KV6 as used in the Rover 800 used MEMS 2J, which controlled the three wasted spark coil packs and variable intake manifold geometry. The later KV6 used Siemens EMS 2000.
All 1100 engines displace 1.1 L (1,120 cc/68 cu in). Four variations were created:
Cars that came with the 1100:
Engine Codes: 14K2F (8V), 14K4F (16V), 14K16 (16V)?
All 1400 engines displace 1.4 L (1,396 cc/85 cu in). Six variations were created:
The K16 82 hp variant is exactly the same as the 103 hp (77 kW) version, apart from a restrictive throttle body designed to lower the car's insurance group; the 90 hp (67 kW) Spi features single-point fuel injection rather than the multi-point of the later engine.
Cars that came with the 1400:
Engine Code: 16K4F
All 1600 engines displace 1.6 L (1,588 cc/96 cu in). Two variations were created:
Cars that came with the 1600:
Engine Codes: 18K4F, 18K4K (VVC variants)
All 1800 engines displace 1.8 L (1,795 cc/109 cu in). Six variations were created:
Cars that came with the 1800: