The K9K is an automobile engine family – a group of straight-4 8-valve turbocharged Diesel engines co-developed by Nissan and/or Renault, and also Daimler AG (where it is called OM607). The turbochargers used with this engine are provided by Garrett and BorgWarner.[10] It has a displacement of 1461 cc and is called 1.5 dCi (direct Common-rail injection). Fuel injection systems were supplied by Delphi on the lower power level versions (up to 66 kW (90 PS; 89 hp) and by Continental (ex Siemens) on the higher power level versions (70 kW (95 PS; 94 hp) and higher). The Delphi injection systems have been replaced with Bosch ones in the Euro 5 versions.[citation needed]

There are three versions of this engine: a low power version, a high power version and a high power version with variable-geometry turbocharger.[11] Their maximum power output varies depending on the emission standards they meet.

In Euro 3 standards, their power levels are 65 PS (48 kW); 80 PS (59 kW); 100 PS (74 kW).

In Euro 4 standards, their power levels are 70 PS (51 kW); 85 PS (63 kW); 106 PS (78 kW).

In Euro 5 standards, their power levels are 75 PS (55 kW); 90 PS (66 kW); 110 PS (81 kW).[11] Torque outputs range from 160 to 260 N⋅m (118 to 192 lb⋅ft) at 1,750 rpm.

The engine has been in production since 2001, with over 10 million units sold as of April 2013. Improvements over this period have included coating the tappets to reduce friction by 40%; redesigning the injector spray angle, resulting in a 15% reduction of NOx during combustion and a small improvement in torque; and fitting new piston rings, reducing the tension on the belt-driving engine accessories and optimizing the dimensions of the base engine. The injection pattern has been altered to have two pilot injections over a wide operating range, reducing combustion noise by up to 3 decibels. Still newer technology also includes using a variable-pressure oil pump, and adding stop/start battery technology and low-pressure exhaust-gas recirculation. The K9K engine is produced in Bursa, Turkey; Chennai, India; and Valladolid, Spain. Emissions-wise, it emits as little 90 g (3.2 oz)/km of carbon dioxide.