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QR25DE

The QR family of straight-4 piston engines by Nissan 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.

Contents

QR20DE

The 2.0 L (1998 cc) QR20DE produces 147 hp (110 kW) and 148 ft·lbf (200 N·m) The bore is 89 mm with a stroke of 80.3 mm and a compression ratio of 9.9:1.[1]

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 ft·lbf (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 ft·lbf (237 N·m) of torque.[4] In the 2005+ Nissan Frontier the QR25DE generates 154 hp (115 kW) and 173 ft·lbf (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 ft·lbf (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:

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Concerns

Manufacturing, design, and assembly flaws

The QR25DE sold in the United States has been subject to a significant number of problems in its short 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 can lead to premature engine failure and possibly a fire. While Nissan investigates the problem, owners of the affected vehicles are being advised to check their oil frequently (every 700 mi (1,100 km) [1127 km]), and dealers have been instructed to place the affected vehicles on sales hold.[9]

Stated versus observed power

In addition to the physical problems suffered by the QR25DE, Nissan's official stated power and torque numbers seem to disconnect from power measurements taken by the general public. Though rated for 177 hp (132 kW) and 172 ft·lbf (233 N·m) of torque in the Nissan Altima and Sentra SE-R, the actual power of the engine may be significantly lower. Multiple dynamometer readings performed by a range of people in an assortment of cars over several years have shown that the engine more than likely produces ~160 hp and ~170 ft·lbf of torque. Parasitic loss alone seems an unlikely candidate for the discrepancy as automatic transmission loss would be approximately 28% and manual transmission loss 19%.[10][11]

However, engine dyno tests performed by Brian Crower, a respected aftermarket parts supplier, shows this engine does indeed perform very close to the advertised numbers. The high weight of the Helical Limited Slip differential which is in many models with this engine, and the very heavy dual mass flywheel likely account for the losses on traditional chassis dynos.

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 ft·lbf (245 N·m).[12]

Vehicle applications:

  • 2002-2006 Nissan Primera P12 (JDM)

See also

References

Enthusiast Websites


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