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.

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.

Getting a fast road cam will help you create more peak power, and we normally suggest it as a main mod on petrol engines and a secondary mod on diesel engines to a remap.

Changing your KR20DDET cam will significantly increase the engine's power. Choosing a higher performance cam profile increases the engine's power.

Fast road camshafts tend to improve performance across the rpm range; you may lose a little low-down horsepower, but your higher-rpm power will be greater.

Competition camshafts increase the higher rpm power band, but the vehicle does not idle smoothly and low end power almost usually suffers as a consequence.

A Competition camshaft will only irritate you when driving through congested metropolitan areas. This is due to the fact that a competition cam generates a very lumpy idle and makes the vehicle more prone to stalling or jerking along in stop-and-go traffic; unfortunately, many people disregard this and wind up damaging a perfectly decent car and having to switch back to a fast road, or OEM cam profile.

Fast road camshafts are one of the most important mechanical improvements, but they must be selected and fitted by someone who understands what they're doing, and they're not always easy to come by. However, you may be able to locate a local outfit to regrind a standard camshaft.

You should preferably match your horsepower range to your car's use, therefore for a daily driver, keep with a moderate fast road cam on the KR20DDET.

Some KR20DDET engines respond better to more or less aggressive cam durations so set your engine up on a rolling road.

The ECU mapping and injectors and fuel pump also have a large bearing on the bhp gains you'll make.

Altering valve durations can alter the bhp band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best Engine Mods for your KR20DDET

    1. Tunes - 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 and superchargers – 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. Fast road camshafts are one of the most important mechanical improvements, but they must be selected and fitted by someone who understands what they're doing, and they're not always easy to come by. However, you may be able to locate a local outfit to regrind a standard camshaft.

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 your KR20DDET.

(In some cases, as the factory ECU is locked flashing is not an option, 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.)

It will normally give you roughly 30% more power on turbocharged cars and around 15% on NA (naturally aspirated) engines, but 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

NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your KR20DDET

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.

When your car is turbo charged upgrades are giving better power gains and you'll see that turbo charged engines are built with uprated components.

However most engines will have power limits.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 Performance Exhausts

You should look to increase your exhaust if the existing exhaust is actually creating a restriction in flow.

On most factory exhausts you'll see your flow rate is still ok even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Do not go with the widest exhaust you can find this will reduce the exhaust flow rate - the best exhausts for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Typically exhaust restrictions are in the catalysts installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

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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