Extreme Engine Tech: Jim Wolf Technology’s Turbo Nissan QR25DE Powerhouse Part 1

Jim Wolf Technology’s Turbo Nissan QR25DE Powerhouse – Part 1

By Mike Kojima

Due to some rather unfortunate decisions within Nissan’s corporate structure, the QR25DE engine has found its way, probably by default to the top of Nissan’s product line up as its flagship performance 4 cylinder engine.  The QR25DE is found in the B15 Sentra SE-R and Spec-V as well as the ultra hideous Sentra B16 SE-R and Spec-V.  In North America, the QR is also found in the Altima, Rogue and as a base Frontier truck engine.


 Nissan QR25DE rod vs SR20DE
It is easy to see how the SR20 rod shown above on the left is much stronger than the QR part.  Look at the general lack of robustness of the QR25DE part on the right and note the thinner rod bolts. The stock SR rod can easily withstand 20 psi of boost and over 400 hp stock.  That cannot be said of the stock QR parts.

We have a love/hate relationship with the QR25DE.  We felt that Nissan completely missed the boat with the engine’s first iteration which was released in 2002.  The engine had a lot of torque and a wide powerband, but the power output trailed it’s competitors such as the Honda K20A, K24, F20 and F22. The QR did not have the delightful high revving fistfuls of power that these Honda engines made, nor the boat anchor robustness of the Toyota 2AZ-FE. The engine’s low, class trailing 6100 rev limit simply hamstrung it from a power perspective and made the engine very unrewarding to drive.  The engine was surrounded by controversy from its first release, starting with Sport Compact Car Magazine’s discovery and publication that Nissan had seriously stretched it’s power claims.  This was confirmed by owners who independently dyno tested their own cars.

QR25DE open deck block
The QR25 has an open deck.  Although this offers improved cooling, open decks often suffer from cracked cylinder walls, poor head gasket sealing and cylinder flexing when subjected to high boost and increased rev limits.  We are not planning for high boost levels or really high rpm so we did not bother to sleeve and close up the block deck like many Honda tuners do.  Sleeving blocks with integrated decks also creates issues with block structural integrity and flex which often hurt bearing life and ring seal so we are going to first try to see if we can make the engine live without sleeves.

The QR25DE seemed to have been released before development was complete as the QR initially was plagued with horrendous design related quality and reliability problems that were so bad, they completely tainted the halo image that the Sentra SE-R had made with enthusiasts over the years.  The QR’s problems were unheard of as Nissan has historically always had a reputation of releasing solid, industry leading engines with exceptional performance and durability.

QR25DE block vs SR20DE block

Compared to the late great SR engine family, the early Nissan QR25DE has a spotted history as a performance engine.  In the performance world it has earned a reputation for being fragile and the many recalls that Nissan has had for serious problems from blowing head gaskets to blowing rods out the side of the block has furthered this reputation.  The engine’s redeeming features are a cylinder head that flows extremely well, a light overall weight and a strongly supported crank and lower end. A fragile engine is not going to work for our time attack Spec-V so we are going to address the engine’s weak points and see if we can turn the QR into a solid performer capable of racing levels of performance and reliability.

QR25DE VS SR20DE rods and pistons
When comparing both side by side, its easy to see that the SR20DE rod and piston on the bottom are much stronger than the QR25DE parts on top.  Compare the thickness of the rod beams.  This is not entirely a result of poor engineering.  The SR20DE was designed to be a robust turbocharged engine while the QR25DE was designed to be lightweight for its displacement.

In 2006 Nissan revamped the QR with many improvements, mainly those which strengthened its reciprocating parts allowing a higher 7000 rpm redline.  This much improved engine also made considerably more power.  This is how the engine should have been in its initial release and if it had been so, the B15 Sentra SE-R Spec-V might have become a lovingly adored vehicle like its predecessors.

Nissan QR25DE block
The QR block makes extensive use of external ribbing to strengthen it without excessive weight.  The QR25DE at 2500cc is 500 cc larger in displacement than the 2000cc SR20DE while weighing less, a significant feat.

Jim Wolf Technology, perhaps the top Nissan tuner is North America was drafted for our engine development program.  JWT brings over 25 years of Nissan experience to our program. We immediately decided that the engine had to be turbocharged for reliability.  The QR25DE has a long 100mm stroke and a short 143.05mm rod with an 89mm bore. Its 1.43:1 stroke to rod length ratio is the worst of any production engine by far.  Obviously this engine was designed for low end torque with no regard for controlling piston speed.

QR25DE bedplate
The QR block features this bed plate which firmly holds the crank in place.  This is much stronger than the traditional main bearing caps that most engines use and is a feature usually found only in racing engines.  The bedplate supported bottom end is one of the QR’s best design features.

To make power naturally aspirated would mean significantly increasing its low 6100 rpm redline.  Long stroke/short rod engines have difficulty staying together at high rpm.  The RTR World Challenge SE-R would go through 3 engines per race weekend.  As we don’t have a factory works team budget; to ensure reliability, we decided not to exceed 7000 rpm.  With such a low redline we would have to turn to forced induction to make power.

Nissan SR20DE crank vs QR25DE crank
The QR crank on the bottom, is only half counterweighted compared to the fully counterweighted SR crank pictured on top. The SR crank’s counterweights are easier to see here.  A fully counterweighted crank is less stressed by torsional vibrations at high rpm.  A bad feature of the QR crank is the lack of overlap between the rod and main journals.  This means that the crank is stroked to the limit and is weak in the area between the journals.



    1. It is a pretty weak engine. It responds well to turbocharging making good power but its hard to make it reliable. The engine has a weak crank, small bearing area, long stroke and poor rod ratio combined with poor water jacketing and poor head sealing make thing problematic. For easy street use and occasional drag racing maybe on low boost but no track days, etc.

      1. I was thinking about starting with a 07+ block and replace the internals with forged parts. Doing something very similar like what you guys did with the QR25DE and probably push it close to 500 but using E85. I love my Nissan’s but I want professional advice before I start spending any more money.

      2. Also the build I want to start is for street use only not track. Daily driver and some drag racing once in a while.

  1. i have an sr20 engine and i am asking if i can do something to my qr20 xtrail.can l use also the rod and then look for the right pistons?
    do i change the compression with this things

  2. So… I have a 2018 Rogue.. Yes, Rogue, that I wanted to explore with performance upgrades. Long have I wanted to have a 500hp+ suv lol don’t judge me :p

    So, I thought about turbocharging it. Came across this article. It made me quite sad tbh 😂 I won’t be tracking it, or even drag racing it. I just want a sprinkle of power to play with while driving.


  3. I have a 2013 Altima with the qr25de and my goal for HP is 250HP. it’s completely stock at the moment. Could you give me some pointers as far as what mods to start with and where to go from there? Thanks.

    1. Possibly, a header, Intake, JWT cams, and a balance shaft delete kit. Then find someone that can tune it. I probably would not modify the engine beyond this.

  4. I really like my Altima coupe I just wish it came turbocharged from factory. It would have sold a lot better and it would stututu.
    So I have been looking at the pre-made “kits” for qr25de engines but they are all around $4900. So instead my question is, would I be able to make a t3/t4 universal turbo kit run safely on my qr25de? I am not looking to make anymore power than around 230-250hp I really do not care about the numbers as long as I can safely get the car to run a t3/t4 turbo. I want to pursue a career in which I work on cars so this wouldn’t be a situation where all I want is power, it would more be a test to see if I am be able to do it… I’ve already changed the stereo, wheels, brakes, exhaust and intake system with no help besides my phone and my tools that I borrow from my very nice neighbors. I don’t have access to a professional garage but I do have a lot of free time due to the pandemic.

  5. Even if I don’t end up turbo charging my Altima coupe I’ll be installing new headers, new cams and a tune. I’ll probably call it a day after that but I still wish from factory the Altima coupe was turbo charged. It definitely has the looks just not the love from Nissan.

  6. Hey y’all, I’m checking out a 2003 sentra SE-R Spec V through a private seller. I’m going to be meeting the owner to check it out, and then I have an appointment at a reliable mechanic shop for a pre-purchase inspection.

    I’ve been looking up the QR25DE and all of it’s faults, I don’t plan on boosting the engine, I just want a fun car with a 6-speed to row through gears during road trips. I don’t need a car to commute, so it’s a hobby vehicle. Seller says they have complete service history from Nissan starting from 2006, and that it has a Nissan factory remanufactured engine with only 36,000 km that was installed by Nissan. The body has a total of 275 km.

    My question is, what red flags should I be looking for?

    I am also looking for:
    Oil leaks from under the cylinder head cover
    Idle problems and/or jerking caused by stretched timing chain
    Random misfires
    High oil consumption (this may take time to ascertain)

    I know it’s not a race car and I know it won’t make 175 hp at the wheels.

    any advice would be greatly appreciated.

  7. So my 2003 se-r qr25de with 157,000 blew a piston today from just driving around. i am thinking of buying another qr25de what should i upgrade on the engine to prevent another piston mishap again? i just want it to be more reliable than the last one. the only issue i had was it burned a lot of oil and required 1 qt about every 2 weeks.

  8. I have an x-trail 2004 qr25de that has spit out the thrust bearing damaged the block and crank, $1000 to repair it has 100,000 k’s everything is good apart from crank, block and bearings. I have another engine it is from a 2009 Nissan Presage, it is a good runner with 325000 k’s I think it is a gen2 engine so I would like to use the block and crank, does this sound reasonable?

  9. Mr Kojima
    Has anyone done a 92mm sleeved post 08′ qr25de all motor to compete with 102mm stroked 2.6L K series hondas? At least the Nissan has a factory 100mm full counter stroke crank post 08 from what I hear. Trav using JW know how was playing with SR20DE cranks in the QR25DE back in 2004 which would make excellent SR20DE replacement motors with more displacement no need for sleeving an SR20DE and then stroking it.

    Finally is a turbo QR25DE with the right internals as heavy as an all motor VQ v6?

    1. There is no way a QR can even come close to competing with a K motor. This motor was never any good and its not worth sinking money into it.

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