DARTON MID ductile iron cylinder liners 77.00-77.50mm MINI Cooper S R56 N14B16 / PSA EP6D (set of 4)

DARTON MID liners are the finest cylinder liners on the market thanks to their strength and their fit. Their flanged tops butt against one another while allowing coolant to flow between them (wet liners). Many production cast iron and aluminium blocks suffer from a design weakness in cylinder stability because of poor support in the upper deck area. The cast-in liner manufacturing process gives economy of scale on low output engines, but it does not support high power, high boost or larger bores.

DARTON has engineered a superior solution using a uniquely designed cylinder liner which, once siamesed and interlocked, creates a strong bridge of liner flanges held in tension. That bridge reinforces the upper deck area and allows individual liners to be replaced by a machine shop. DARTON calls this principle the Modular Integrated Bridge (MID). DARTON designs also manage and improve water flow from block to head to promote cooling stability, and every liner is of wet design.

Improving water flow in and around the flange area is made possible by the orifice water flow control engineering DARTON calls Swirl Coolant Technology. The process starts from the specific technical designs of the cylinder head and combustion chamber concerned, then increases water flow to the areas of the upper liner subjected to the most heat. There is a different engineering model for each engine and cylinder design. While heat is generally taken to translate into energy, high resident heat in the combustion chamber can lead to detonation, the primary cause of engine failure at high power. High rpm normally results in efficient exhaust of the airflow, but where there are misfires or incomplete flame spread, high cylinder pressures and temperatures are created. The MID design compensates for this high heat absorption condition.

In the normal installation of dry liners, the cooling medium, water, has to transfer the absorbed heat through the block material and through the liners, which may be different metals. When dry liners are pressed in with an interference fit, the interface between the materials is never perfect, which further worsens heat transfer. This thermal conductivity is inefficient and, as more heat is generated, the combustion process is compromised. Even in the wet designs of the past, water was never treated or circulated effectively between block and head to ensure maximum heat dissipation from the combustion chamber. A certain amount of standing water is inherent in cast iron or aluminium open deck and closed deck engine blocks. It is like pouring water into a funnel: there is no real flow or speed until the water comes out of the spout. On blocks and heads the casting ports are designed for ease of pouring, not for efficient flow. With DARTON MID swirl cooling technology the coolant is routed and directed to improve heat transfer significantly where it is needed most, in the upper cylinder wall and flange area.

The DARTON Pro-Sleeve kit is available for many series of 4, 6 and 8 cylinder import and domestic engines and offers maximum bore sizes and boost potential. The advantages of our Pro-series kits are:

• Improved integral block strength
• Improved cooling
• Replacement possible as a wet liner
• Increased power production potential
• Superior oil and compression control
• Street or strip application
• Kits can be fitted by your local machine shop
• Full installation manual supplied with every kit
• High boost and power potential, superior cylinder sealing and reduced ring wear
• DARTON bulletproof ductile iron, tensile strength of 130,000 psi