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Nissan QR engine

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QR25DE

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

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

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

The QR25DE is a 2.5 L (2488 cc) variant built in Decherd, TN 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 of 9.5:1.[3] 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.[4] In the 2005+ Nissan Frontier the QR25DE generates 154 hp (115 kW) and 173 lb⋅ft (235 N⋅m) of torque.[5] More recently, in the Nissan SE-R Spec V 2007+ the QR25DE generates 200 hp (150 kW) @ 6600 rpm and 180 lb⋅ft (240 N⋅m) of torque @ 5200 rpm with a 7000 rpm redline. The crankshaft comes fully balanced allowing removal of the counter-shafts built into the older style QR25. The newer version is also equipped with a composite intake manifold and compression has been bumped up to 10.5:1 [6]

Vehicle applications:

Concerns

Manufacturing, design, and assembly flaws

The QR25DE sold in the United States has been subject to a significant number of problems in its lifetime. A variety of mechanical flaws have led to numerous technical service bulletins, recalls, repairs, and outright engine replacements.

  • Vehicles with the QR25DE may ingest material from a damaged pre-catalyst resulting in increased oil consumption.[7]
  • Power valve screws in the intake manifold may become loose and result in unstable idling or power loss.[8]
  • In June 2006, it came to Nissan's attention that approximately 85,000 Altimas and 2,000 Sentra SE-Rs equipped with the QR25DE and built between January and May 2006 may experience unusually high oil consumption. This could have led to premature engine failure and possibly a fire. The issue was resolved by reprogramming the ECM [9]

2007+ QR25DE

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. No more troublesome butterfly valves. (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. This also means JWT's balance shaft removal kit for the 1st gen QR will not work.
  • 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.
  • Oil consumption issue resolved from older QR25DE.
  • Higher rev limit and improved power output.

QR25DD

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).[10]

Vehicle applications:

See also

References

External links

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