In terms of longevity, power, and appeal to the mass, we cannot count out the engine that powered the Nissan SE-R. You can see them rolling on the streets with their nice sound, dynamic driving look, and the attitude it brings to the owner. The engine we are talking about is the QR25DE engine which is still used up to this day.
So today, let us discuss the QR25DE engine’s design, applications, versions, modification, issues, reliability, tuning potential, aftermarket support, and many more.
What are Nissan QR25DE engines?
The Toyota QR25DE engine is a 2.5 Liter, straight-four gasoline engine manufactured by Toyota from 2001 up to the present. It has the exact technicalities of the QR20DE engine except for some upgrades.
This engine features a new crankshaft, Aluminum cylinder head, and block. It uses two overhead camshafts, a four-valves per cylinder design with continuously variable valve timing (CVTC) on the intake camshaft, electronic throttle, individual ignition coils, and multi-point fuel injection system. The QR25DE engine is built with a steel timing chain, steel connecting rods, aluminum intake manifold, and counter-rotating balance shafts.
The early generation release of the QR25DE engine had these features, and a follow-up update was made in 2007 to integrate other technologies, which we will discuss further down below.
QR25DE engine is a member of the inline-four series of the QR family, and it became the substitute for the KA24DE engine.
Engine Specifications and Design:
- Production Run: 2001 – Present
- Cylinder Head Material: Aluminum
- Cylinder Block Material: Aluminum
- Configuration: Inline-4
- Bore: 89 mm
- Stroke: 100 mm
- Valvetrain: DOHC with four valves per cylinder
- Displacement: 2.5 L (2488 cc)
- Compression Ratio: 9.5 to 10.5
- Weight: 330 lbs.
- Max HP: 200 HP at 6,000 RPM
- Max Torque: 181 lb-ft at 3,900 RPM
The QR25DE engine is the 2.5 L variant of the QR engine family. The QR25DE powerplant has an aluminum cylinder block with an 89 mm bore and a longer piston stroke of 100 mm. The compression ratio ranges from 9.5 to 10.5, depending on the vehicle model.
The pistons are each fitted with a single oil ring and two compression rings. The connecting rods are made from cast steel which is 143 mm long. QR25DE crankshaft is supported by five main bearings and two counter-rotating balancer shafts for an added stability of movements.
The QR25DE has an aluminum intake manifold, aluminum cylinder head with two overhead camshafts driven by a steel timing chain. It is integrated with a variable valve timing system (CVTC) on the intake camshaft. The intake valves are 35.5 mm in diameter, and the exhaust valves are 30.5 mm in diameter.
This particular engine has special valve lifters to adjust the valves instead of the hydraulic lifters.
This early version of the QR25DE engine produces 175 HP at 6,000 RPM with 180 lb-ft of torque at 4,000 RPM in the Altima 2.5 and Sentra SE-R vehicles. PZEV compliant Altimas is rated at 170 HP and 175 lb-ft of torque.
Several years after its successful launch, Toyota decided to revise the initial release of the QR25DE engine, which you can find in the 2007 and later models of Rogue, Sentra, Altima. Some improvements of the QR25DE engine over the older QR20DE include:
- Higher rev limit and larger power output
- Reinforced connecting rods that are only made available in the Sentra SE-R Spec V 2007 – 2012
- Revised camshaft profile
- Revamped piston crown shape to support a higher compression ratio as well as reduced friction in relation to the coatings used on pistons, journal bearing, and other moving components
- The balancer system has been relocated slightly at the back from the crank pulley to a more centric location in the engine block
- Additional engine mount on the motor top near the pulley side
- Simpler but larger diameter single path resin intake manifold to replace the outdated dual-path design
Toyota released a supercharged version of the QR25DE engine under the name of QR25DER, which is similar to the QR25DE engine but is coupled to a 20 HP electric motor. It also features a dual-clutch system and lithium-ion batteries for increased fuel efficiency. This engine produces a combined 250 HP at 5,600 RPM, 243 lb-ft of torque at 3,600 RPM, and a 9.1 compression ratio.
Another one is the QR25DD which is also similar to the QR25DE but has a higher compression ratio of 10.5 and is installed with direct injection. This is the first QR engine to use DLC coating on the valve lifter buckets to reduce friction. This version produces 168 HP at 5,600 RPM and 181 lb-ft of torque at 4,000 RPM. You can find this engine in the 2002 – 2006 Nissan Primer P12 (JDM)
Applications of the QR25DE Engine:
- 1999 – 2003 Nissan Bassara
- 2001 – 2005 Nissan Serena C24
- 2001 – 2007 Nissan X-Trail T30
- 2002 – 2006 Nissan Sentra SE-R and SE-R Spec V
- 2002 – 2009 Nissan Presage
- 2002 – Present Nissan Altima
- 2003 – 2005 Nissan Teana
- 2003 – Present Nissan Murano (Japan only)
- 2005 – Present Nissan Frontier
- 2007 – 2012 Nissan Sentra SE-R and SE-R Spec V
- 2007 – 2011 Nissan Altima Hybrid
- 2007 – Present Nissan X-trail T31
- 2007 – Present Renault Koleos
- 2008 – Present Nissan Rogue
- 2009 – 2012 Suzuki Equator
- 2013 – Present Nissan Teana
- 2013 – Present Nissan X-Trail T32
- 2010 – Present Nissan Elgrand E52
- 2018 – Present Nissan Terrea
- 2020 – Present NIssan X-Terra
Engine Tuning, Upgrades, and Modification
There are two options for you if you want to tune your QR25DE engine, the naturally-aspirated build and the turbocharged one. It is up to you what to do with the machine, and how well does it perform solely depends on the upgrades you use.
So, to start with the naturally-aspirated build, take note first that QR25DE engines are developed for the low-end torque range, as we can observe in the piston stroke length. To increase your engine’s power, you need to buy performance parts such as cold air intake, balancer shaft removal kit, aftermarket exhaust system, Nissan Sentra SE-R Spec V cams, and 4-2-1 header. We chose the SE-R Spec V cams because they are far more aggressive and superior in pushing the engine’s redline limit up to 7,000 RPM. After installing these upgrades, tune the ECU, and this can give you at least 200 horsepower, good dynamics, and pleasant sound. If you bought QR20DE pistons, the compression ratio would increase to 11.5, and with that, the power will also increase to 220 horsepower, at best.
Bolting turbo in the QR25DE engine is not easy because the stock engine does not fit for a boost like this; add to that are weak connecting rods and easily burnt pistons which are extremely sensitive when putting turbos. However, you can solve that by buying forged internals, buy new connecting rods, forged pistons with 5 mm piston ring offset, and install oil nozzles for piston cooling. You need to purchase an MLS head gasket, Garrett GT28 turbo, turbo manifold, thermal insulation, boost controller, wastegate, intercooler, ARP head studs, blow off valves, oil feed line, oil return line, 630 cc/min fuel injectors, Walbro 255 lph fuel pump, 3-inch exhaust system, MAF, and APEXI. After you install all these upgrades, this can give you an easy 300 horsepower.
Problems Surrounding Nissan QR25DE Engines
There are no perfect engines, even though some are over-engineered or overly modified. Still, the fact remains that there will come a time that engines will go down in your engine history and retire, but that is not easy because we want our machine to last long as possible and get the most out of it while it is still running. The same goes for the QR25DE engine that has some minor issues that need to be addressed so that potential owners of this engine have a slight sense of idea regarding the problems that may arise in the QR25DE engine. Here are some issues or concerns that might affect the engine:
First is the idling problem. Idling problems occurs because of the inconsistent air-fuel mix burn inside the combustion chamber. When that happens, idling becomes a struggle and sometimes causes shaking. This problem might be due to a stretched timing chain. If that is the case, replace the old timing chain with new ones.
Next is the oil leak. Valve cover gaskets are often the culprit of such problems. This is common to gaskets because they are heavily subjected to changing temperatures and processes, thus starting to wear out the gaskets. They become soft, brittle, or sometimes flat-out broken.
There are also cases of excessive oil consumption of the QR25DE engine. Age and mileage are the main contributors to this issue, also considering the second-hand engines. If your oil consumption exceeds one qt per 1500 miles, then most likely you have loose piston rings, and valve seals or piston rings have got out of order. If not correctly solved, this can escalate to misfiring.
Unnecessary vibrations are also noticeable in the QR25DE. These vibrations pose serious harm, especially to the moving parts of the engine. This happens mainly due to lame soft ECU, which needs replacement. Spark plugs might also be the reason because faulty spark plugs cause the pistons to move more aggressively as they keep on pumping and pumping.
QR25DE engine also has little to no resistance to cold weather regions as they find it hard to start up in conditions below -4 Fahrenheit. This is maybe due to damp, frozen spark plugs that affect its burning or sparking capabilities.
Catalytic converters are often faulty, which burns a lot of fuel. That connects it to the thermostat problem on both the QR20DE and the QR25DE engine’s thermostat. Thermostats are essential indicators of operating temperatures. If they are faulty or broken, it dramatically affects the engine performance as you keep treading on murky waters because you have no idea of the working temperature in the engine. If not adequately replaced, that results in an engine overheat and eventual failure.
The QR25DE engine has its fair share of good and bad sides; it has shortcomings and lacks in some departments. But we cannot erase the fact that this engine is modern with its features such as lightweight materials, counter-rotating balance shafts, and many more. It is an engine ahead of its time, the engines’ fuel economy, having a lot of choices, a wide array of power output, and overall engine stability. It has some issues and problems that account for its lower trading value for some, but without this kind of engine, we cannot figure out how to make a good one. With proper maintenance and care, for sure, this engine can floor the majority of other inline-four out there.
I hope that this simple discussion helped you understand the QR25DE engine’s power output, applications, tuning potential, aftermarket support, issues, problems, and overall impact on the industry and community.