Nissan QR engine

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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.

QR20DE[edit]

QR20DE

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.[1] The QR20DE was replaced with the MR20DE.

Vehicle applications:

QR20DD[edit]

The QR20DD is similar to the QR20DE but features NEO direct injection to improve fuel economy and to reduce emissions.[2] It produces 150 hp (110 kW).

Vehicle applications:

QR25DE[edit]

QR25DE

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.[1]

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.[3] In the 2005+ Nissan Frontier the QR25DE generates 152 hp (113 kW) and 171 lb·ft (232 N·m) of torque.[4] 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 [5]

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 once 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.

Vehicle applications:

2007+ QR25DE[edit]

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.

QR25DD[edit]

The QR25DD is similar to the QR25DE but increases the compression ratio to 10.5:1 and includes direct injection. It produces 170 hp (125 kW) and 181 lb·ft (245 N·m).[6]

Vehicle applications:

QR25DER[edit]

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. [2]

Vehicle applications:

See also[edit]

References[edit]

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