Nissan MR engine

The Renault-Nissan MR engine family consists of three and four-cylinder, all-aluminium and water cooled automobile engines with variable valve timing, initially developed by Renault and Nissan, and also Mercedes-Benz since 2010 in the case of the M9T/OM699. They all have four valves per cylinder. Renault calls this engine family the M engine. Other noteworthy features of this engine family include acoustically equal runner lengths and a tumble control valve for the intake manifold, a "silent" timing chain, mirror finished crankshaft and camshaft journals, and offset cylinder placement in an attempt for increased efficiency. The MR engine family features 'under stress' manufacture, meaning while the block is being bored, a torque plate puts the block under stress. The block becomes temporarily distorted until the head is torqued onto it, at which point the block is pulled into the correct shape.