Nissan QR engine
The QR family of straight-4 piston engines by Nissan were introduced in 2000 and range from 2.0 L to 2.5 L in displacement. These motors are aluminum, dual overhead camshaft (DOHC), four-valve designs with variable valve timing and optional direct injection.
The 2.0 L (1998 cc) QR20DE produces 147 hp (110 kW) and 148 lb·ft (200 N·m) The bore is 89 mm with a stroke of 80.3 mm and a compression ratio of 9.9:1. The QR20DE was replaced with the MR20DE.
- 2001-2007 Nissan X-Trail T30 (140 hp)
- 2001-2007 Nissan Primera P12
- 2002–present Nissan Serena C24, 145 hp (108 kW)
- 2003-2008 Nissan Teana J31, 145 hp (108 kW)
- 2001-2005 Nissan Wingroad Y11
- 2002-2005 Nissan Avenir W11
- 2001-2004 Nissan Prairie M12
- 2000-2004 Nissan Bluebird Sylphy
The QR25DE is a 2.5 L (2488 cc) variant built with cast steel connecting rods, a steel timing chain, counter-rotating balance shafts, and an aluminum intake manifold. The engine bore is 89 mm with a stroke of 100 mm and a compression ratio ranging from 9.5:1 to 10.5:1 depending on the vehicle.
Output is rated 175 hp (130 kW) at 6000 rpm with 180 lb·ft (244 N·m) of torque at 4000 rpm in the Altima 2.5 and Sentra SE-R models. Altimas that are PZEV compliant create 170 hp (130 kW) and 175 lb·ft (237 N·m) of torque. In the 2005+ Nissan Frontier the QR25DE generates 152 hp (113 kW) and 171 lb·ft (232 N·m) of torque. The crankshaft comes fully balanced allowing removal of the counter shafts built into the older style QR25. The newer versions are also equipped with a composite intake manifold and compression has been bumped up to 10.5:1 
Nissan has issued several recalls on early QR25DE engines relating to excessive oil consumption. The most notorious example of engine oil consumption recalls relates to 2002 Nissan Sentra Se-R Spec-V vehicles. Recalls noted failure of the engine exhaust manifold catalyst due to excessive oil consumption leading to contamination of the catalyst and failure. Nissan replaced QR25DE engines under recall often more than one time on the same vehicle. The cause of engine oil consumption is due to a combination of closer piston ring placement towards the crown of the piston, overheating of the piston rings, failure of piston rings to seal correctly, and long stroke distance of the piston within the cylinder. contamination of catalyst substrate with oil eventually causes the catalyst to ignite and restrict exhaust flow, the result is exhaust backpressure increase along with overheating of the exhaust system and exhaust connected side of the engine.
- 1999-2003 Nissan Bassara- 165 hp (123 kW)
- 2001–2005 Nissan Serena C24- 158 hp (118 kW)
- 2001-2007 Nissan X-Trail T30 APEC export version- 178 hp (133 kW)
- 2002-2006 Nissan Sentra SE-R- 165 hp (123 kW) & SE-R Spec V- 175 hp (130 kW)
- 2002-2009 Nissan Presage- 165 hp (123 kW)
- 2002–present Nissan Altima 170 hp (127 kW) to 182 hp (136 kW)
- 2003-2005 Nissan Teana- 160 hp (119 kW)
- 2003-present Nissan Murano (Japan)
- 2005–present Nissan Frontier- 152 hp (113 kW)
- 2007–2012 Nissan Sentra SE-R- 177 hp (132 kW) & SE-R Spec V- 200 hp (149 kW)
- 2007–2011 Nissan Altima Hybrid 158 hp (118 kW), combined 198 hp (148 kW)
- 2007–present Nissan X-Trail T31- 169 hp (126 kW)
- 2007–presentRenault Koleos TR25- 169 hp (126 kW)
- 2008–present Nissan Rogue- 170 hp (127 kW)
- 2009–2012 Suzuki Equator- 152 hp (113 kW)
- 2013-present Nissan Teana- 165 hp (123 kW)
- 2013-present Nissan X-Trail T32- 169 hp (126 kW)
The revised QR25DE found in the 2007+ Sentra, Altima, Rogue, etc. has a number of improvements over the older QR25DE. These include:
- A simpler, larger diameter single path resin intake manifold replaced the old dual path design. (Note: California emissions models do have a swirl control valve located in the intake)
- Revised piston crown shape to support a higher compression ratio of 9.6:1.(10.5:1 in Sentra SE-R Spec V.)
- The balancer system has been moved back slightly from the crank pulley to a more central location in the block.
- Revised cam shaft profile.
- Reinforced connecting rods.
- Reduced friction likely through Nissan's extensive use of coatings on pistons, journal bearings, etc.
- Additional engine mount on the top of the motor, pulley side.
- Higher rev limit and improved power output.
- 2002-2006 Nissan Primera P12 (JDM)
The QR25DER is similar to the QR25DE but has a supercharger for increased power and is coupled with a 15 kW electric motor, Dual Clutch System, and lithium-ion battery for increased fuel efficiency. The engine has a compression ratio of 9.1:1 and produces a combined 250 hp (190 kW) at 5600 rpm and 243 lb·ft (329 N·m) at 3600 rpm. 
- "2007 Nissan Altima overview"
- "2007 Nissan Altima specifications"
- "2006 Nissan Altima specifications"
- "2006 Nissan Frontier specifications
- "2006 Nissan Sentra specifications"
- "Global Vehicles", by Jack Yamaguchi, "Automotive Engineering International", June 2001, retrieved June 29, 2006
- "NTB03070 Nissan technical service bulletin regarding engine precatalyst failure"
- "NTB06045 Nissan technical service bulletin regarding low oil levels"
- "NTB05058 Nissan technical service bulletin regarding power valve screws"
- "Road Test: 2002 Nissan Sentra SE-R" by Josh Jacquot, "SportCompactCar", December 2001, retrieved June 26, 2006
- "Technobabble: December 2001 by Dave Coleman, "SportCompactCar", December 2001, retrieved June 26, 2006