Nissan KR20DDET Tuning Mods

"All you need to know about tuning the Nissan KR20DDET engine!"

The Nissan KR20DDET are good project engines and with the right performance enhancements like remapping, turbo kits, and camshafts you will greatly increase your driving pleasure. At the 2016 Paris Motor Show, Nissan introduced the KR20DDET as the VC Turbo, which included Nissan's unique variable compression technology.

Another standout feature is the incorporation of variable valve timing, a technology that optimizes the timing of the valve lift event, which occurs as the engine runs.

This technology not only improves the engine's performance but also contributes to better fuel efficiency and reduced emissions.

It was billed as the world's first commercially available variable compression ratio engine. Nissan estimates a 25% increase in QX50 fuel efficiency with crisp throttle response.

Our aim here is to examine KR20DDET tuning and point out the greatest modifications for your car.

History, Power & Specs of the KR20DDET Engine

This Variable Compression Turbo has an endlessly variable piston stroke and an effective compression ratio ranging from 8:1 to 14:1. The low-compression mode is designed for strong power demands and heavy road loads, while the high-compression mode is designed for cruising and light loads. The engine was first used in Nissan manufacturing vehicles in 2019 in the Infiniti QX50 and Nissan Altima, replacing the previous V6 choices.

  • 2017–present Infiniti QX50 (J55)
  • 2021–present Infiniti QX55 (J55)
  • 2022–present Infiniti QX60 (L51) (China)
  • 2018–present Nissan Altima (L34)

Tuning the Nissan KR20DDET and best KR20DDET performance parts.

Best KR20DDET modifications

When discussing the best modifications for your KR20DDET engine, we will focus on those that provide the most power for the least amount of money.

When it comes to enhancing engine performance, fast road cams have historically played a pivotal role. These are specifically designed camshafts that increase the lift and duration of the valve openings in the engine to allow more air and fuel into the combustion chamber.

In engines without VVT, fast road cams serve as a fixed upgrade that pushes the engine's limits by allowing it to breathe better.

But are they still relevant in engines with variable valve timing (VVT)?

This means more power at higher RPMs, which can be great for certain driving conditions or specific performance needs.

However, in engines with VVT like the KR20, the system already optimizes the valve timing for varying conditions. So, what does this mean? Essentially, the engine can adjust itself to deliver more power when necessary or operate more efficiently when power is not the priority.

Given this capability, installing fast road cams in a VVT-equipped engine might not provide the significant performance boost one might expect.

The VVT system is already doing the job of optimizing the engine’s breathing based on real-time driving conditions, making the benefits of fast road cams less impactful. (Enhanced lift is pretty much the only argument for cam upgrades, but you'll not gain very much power.)

The ECU mapping and injectors and fuel pump also have a large bearing on the bhp gains you'll make with any mods you apply so never overlook these vital items.

Altering valve durations can alter the bhp band and there are some advantages to extending the intake or exhaust durations at certain RPM points.

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Best Engine Mods for your KR20DDET

    1. Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives on hard to map ECU's.
    2. Intake and Exhaust - Keep in mind that these changes will NOT ADD POWER ON THEIR OWN in most circumstances, but they may aid boost power after other mods by eliminating the limitation.
    3. Upgrades to turbochargers  – forced induction is the most efficient way to increase air supply, enabling you to burn more gasoline while producing more power. It is one of the most expensive modifications, but it delivers the finest results.
    4. Internal engine mods - lighter flywheel, head porting and flowing and stroker kits all help to raise the headline power but these are not cheap upgrades.

KR20DDET Tuning stages

Typical stage 1 mods often include:
drilled & smoothed airbox, Intake manifolds, Fast road camshaft, Panel air filters, Remaps/piggy back ECU, Sports exhaust header/manifold.

Typical stage 2 mods often include:
Sports catalyst & performance exhaust, induction kit, Fast road cam, high flow fuel injectors, fuel pump upgrades, Ported and polished head.

Typical stage 3 mods often include:
Adding or Upgrading forced induction (turbo/supercharger), Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves), Twin charging conversions, Crank and Piston upgrades to alter compression, Competition cam.

The KR20DDET power plant respond well to mods and thanks to their popularity there is a growing number of mods and performance parts out there.

ECU flashing helps to establish the full potential of all the parts you've done to on a project car, but these KR20DDET are proving hard to map or tune directly.

So an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.

We normally recommend Nistune but they don't seem to have a unit compatible with the KR20DDET if you are aware of any good aftermarket ECU's or piggyback options I'd be very eager to hear from you in the comments below (a lot of people have asked me and I've not found a solution yet.)

So theoretically an aftermarket ECU should give you roughly 30% more power on turbocharged car the final outcome will depend on the items you've installed and the state of your engine.

Any engine tuning process requires pushing air and gasoline into each cylinder.

Headers enable air to be sucked into the engine and combined with gasoline from the intake filter.

The Plenum's structure and flow rate may have a significant impact on fuel atomisation and engine efficiency on the KR20DDET.

Although some manufacturers produce relatively well-designed plenum chambers, most plenum chambers are ready for an improvement.

Big valve conversions on the KR20DDET, carrying out 3 or 5 angle valve jobs and porting and head flowing will also lift performance, and as an added benefit will raise potential for a greater performance increase on other tuning parts.

KR20DDET Turbo upgrades

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes massive power gains (as long as it has sufficient fuel).

Most engines will have power limits generally the fuel supply, then crank rods and pistons start to fail at higher power figures. See where you'll find these limits and fit stronger pistons, crank and engine components to handle the power.

We see many guys spending a a stack of money on turbo upgrades on the KR20DDET only to have the car go up in smoke just after it's been enthusiastically driven.

Big turbo chargers commonly suffer a bottom end lag, and low capacity turbo chargers spool up really quickly but won't have the peak end torque gains.

Thankfully the range of turbo units is always improving and we are seeing variable vane turbo units, where the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo units divert the exhaust gases into a couple of channels and flow these at differently angled vanes in the turbo charger. They also improve the scavenging effect of the engine.

It is not unusual that there's a limit in the air flow sensor MAP/MAF/AFM on the KR20DDET when loads more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp and torque gains, although more challenging to get working. We have this feature on twinchargers if you want to read more.

KR20DDET Fuelling

You will need to ensure that the engine is not starved of fuel so will have to pay attention to the fuelling when you start exceeding 20% of a power increase. We strongly recommend you to over specify your injector capacity.

As a rule of thumb add 20% when fitting an injector, this takes into account injector deterioration and provides some spare capacity should the engine need more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

KR20DDET Internal Mods

Tweaking an engine's internals is a well-trodden path to achieving superior performance but can be costly compared to the benefits you yield. But why do people choose to invest in internal engine modifications, and what are the specific benefits and considerations of each?

Let’s dive deeper into three popular types of internal mods: lighter flywheels, head porting and flowing, and stroker kits.

Lighter Flywheel – Boosting Engine Responsiveness

A lighter flywheel is a favorite among performance seekers for a good reason. The flywheel, a substantial disc attached to the crankshaft, serves as a momentum store, helping regulate engine speed by maintaining rotational inertia.

Why go lighter? A lighter flywheel reduces the rotational mass, allowing the engine to rev up and down more quickly.

This results in faster throttle response and quicker acceleration, which can be a significant advantage both on the race track and during spirited street driving.

The principle here is simple: less mass requires less energy to move. By reducing the weight of the flywheel, you're effectively making it easier for the engine to spin up.

This mod is particularly popular because it enhances the "feel" of the engine, making it seem more agile and lively.

Head Porting and Flowing – Maximizing Airflow Efficiency

Head porting and flowing involve modifying the engine’s cylinder head, the component that sits above the cylinders and houses components such as valves, spark plugs, and fuel injectors.

The process entails reshaping the intake and exhaust ports to improve airflow. But why does this matter? Improved airflow means that more air can enter the combustion chamber, and more exhaust can exit, both of which are crucial for increasing power output.

Skilled technicians will often reshape and smooth the ports to reduce any restrictions and optimize the path of airflow.

This can lead to significant improvements in the engine’s ability to "breathe" efficiently at higher RPMs, directly translating to better performance.

While the gains can be impressive, this is a highly skilled task requiring significant expertise and precision, hence the higher cost.

Stroker Kits – Increasing Displacement for More Power

A stroker kit alters an engine’s displacement by increasing the length of the crankshaft stroke, one of the most direct methods of boosting engine power. This can be done by using a different crankshaft, altering the connecting rods, or changing the pistons. But what does this achieve? More stroke means each piston can displace more air and fuel with every revolution, leading to a more powerful combustion process.

The result is not only more power but often more torque across a wider engine speed range, making the vehicle feel more robust and capable under various driving conditions. The trade-off, however, is that this is a comprehensive and invasive modification that usually requires significant engine disassembly and professional assembly, driving up the cost.

KR20DDET Performance Exhausts

When tuning your car for higher performance, assessing the efficiency of your exhaust system is crucial. Initially, your factory exhaust might seem adequate even with moderate power upgrades but you'll eventually hit a restriction.

As you increase your engine's power output, the factory setup may no longer suffice due to limitations in its design to handle greater exhaust flows.

Understanding Exhaust Flow, Back Pressure, and Velocity

The exhaust system's main function is to expel combustion gases from the engine efficiently, allowing the engine to breathe better and perform more effectively. The key to an efficient exhaust system lies in balancing exhaust flow, back pressure, and velocity.

Exhaust Flow: This refers to the rate at which exhaust gases pass through the exhaust system. An unrestricted flow allows the engine to expel gases swiftly, thereby increasing its ability to ingest more air and fuel for combustion.

A restricted flow, often due to narrow or poorly designed exhaust components, can choke the engine, limiting performance.

Back Pressure: While many assume that lower back pressure is always better, a minimal amount is actually beneficial, especially for maintaining low-end torque.

Excessive back pressure, however, is detrimental as it forces the engine to work harder to push out exhaust gases, effectively reducing efficiency and power.

Velocity: The speed at which exhaust gases exit the system is also crucial. If the exhaust gases move too slowly due to an overly large exhaust diameter, it can lead to poor scavenging of gases at lower engine speeds. Conversely, if the exhaust is too narrow, it restricts the flow and increases back pressure unnecessarily.

Choosing the Right Exhaust Size and Type

For optimal performance gains, selecting the right diameter for an exhaust system is more crucial than merely choosing the largest one available.

Exhaust systems typically ranging from 1.5 to 2.5 inches in diameter are often ideal for many performance cars. It's not just the bore size that matters, but also the shape and material of the exhaust system, which can influence both the flow and longevity of the system.

Upgrading with High-Performance Catalysts

Many factory exhaust systems incorporate catalysts that create significant bottlenecks due to their dense structure, which is necessary to meet emissions standards.

Replacing a restrictive factory catalyst with a high-flowing performance catalyst can markedly enhance the exhaust flow.

This upgrade allows for better air flow through the system without removing the catalytic converter altogether, which would be illegal in many regions and could result in your vehicle being non-compliant with road regulations.

Choosing a high-flow catalyst over a straight decat (removal of the catalytic converter) ensures you boost performance while keeping your vehicle road legal.

Such catalysts are designed to reduce emissions but with a less obstructive flow path, ensuring you don't compromise on either legality or performance.

Weak spots, Issues & problem areas on the KR20DDET

The KR20DDET engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the KR20DDET, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your KR20DDET engine please join us in our friendly forum where you can discuss with our KR20DDET owners. It would also be worth reading our unbiased articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which upgrades work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these KR20DDET tuning guides which get regular updates and revisions.

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