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 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.[WIKI]
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