Nissan QR engine
From Wikipedia, the free encyclopedia
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.
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[edit] QR20DE
The 2.0 L (1998 cc) QR20DE produces 150 hp (110 kW) and 148 ft·lbf (200 Nm) The bore is 89 mm with a stroke of 80.3 mm and a compression ratio of 9.9:1.[1]
Vehicle applications:
- 2001-present Nissan X-Trail (140 hp)
- 2001-present Nissan Primera P12
- 2002-present Nissan Serena C24, 145 hp (108 kW)
[edit] 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.
Vehicle applications:
- 2000-2004 Nissan Bluebird Sylphy
[edit] QR25DE
The QR25DE is a 2.5 L (2488 cc) variant built in Decherd, TN with forged steel connecting rods, a steel timing chain, counter-rotating balance-shafts, and a nylon 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 Nm) of torque at 4000 rpm in the Altima and Sentra SE-R Spec V models. Altimas that are PZEV compliant create 170 hp and 175 ft·lbf of torque. Engines in the Sentra SE-R model have 165 hp (123 kW) with 175 ft·lbf (237 Nm) of torque. [4] Most recently in the 2005+ Nissan Frontier the QR25DE generates 154 hp and 173 ft·lbf of torque.[5]
Vehicle applications:
- 2002-present Nissan Sentra SE-R & SE-R Spec V
- 2002-present Nissan Altima 2.5, 2.5S , 2.5SL, Hybrid
- 2001-present Nissan Serena C24, 158 hp (118 kW)
- 2001-present Nissan XTrail APEC export version, 178 hp (133 kW)
- 2005-present Nissan Frontier King Cab XE 4x2
- 2003-2005 Nissan Teana 160 hp and 240 nm
[edit] Concerns
[edit] 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 engire fire and/or failure.[6]
- Power valve screws in the intake manifold may become loose and result in unstable idling or power loss.[7]
- 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 [1127 km]), and dealers have been instructed to place the affected vehicles on sales hold.[8]
[edit] Stated versus observed power
In addition to the physical problems suffered by the QR25DE, Nissan's official stated horsepower and torque numbers seem to disconnect from power measurements taken by the general public. Though rated for 175 hp and 180 ft·lbf of torque in the Nissan Altima and Sentra SE-R Spec-V, 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%.[9][10]
Nissan's revised power claim of 175 hp at 6000 rpm is more realistic than the original 180-hp claim, but is still a long way from the 141 hp produced on the dyno. Our experience with the drivetrain loss varies greatly (see "Technobabble", page 22), but it seems unlikely any front-drive transaxle could make 34 hp evaporate into thin air.
– Josh Jacquot , SportCompactCarWeb, 2001
Nissan has since revised horsepower and torque figures for the modified QR25DE that will be featured in the redesigned 2007 Altima. This new estimate of 175 hp and 180 ft·lbf is based on a revised balancer system, larger intake manifold, and a slightly increased compression ratio of 9.6:1.[11] Moreover, the new figures adhere to the stricter SAE requirements published in 2004 whereas the older numbers were published under the much more lax 1995 SAE standards.
"Honestly if you take into consideration that the engine losses 20% of stated power output at the wheels then the above stated fact that the engine produces 175 hp is not really off. A 20% driveline loss would equate close to 35 hp. A measurement taken at the wheels with that precentage taken into account would equal about 140 whp. Most dynometer test record from the wheels rather than the crank so it is safe to assume that the vehicle is making close to the stated power level." ~Annoymous [12][13]
[edit] 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 Nm).[14]
Vehicle applications:
- 2002-2006 Nissan Primera P12 (JDM)
[edit] See also
[edit] References
- "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
