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The QR25DE is a 2.5 L (2488 cc) variant of QR20D engine 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.
The revised QR25DE found in the 2007+ Sentra, Altima, Rogue, etc. has a number of improvements over the older QR25DE.
- 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 centric location in the block.
- Revised camshaft profile.
- Reinforced connecting rods only available in the Sentra SE-R Spec V 2007-2012 .
- Reduced friction likely through Nissan’s extensive use of coatings on pistons, journal bearings, etc.
- Additional engine mounts on the top of the motor, pulley side.
- Higher rev limit and improved power output.