Renault K7J Tuning

"All you need to know about tuning the Renault K7J engine!"

The Renault K7J make awesome project engines and with the optimum modified parts like remaps, turbo kits and camshafts you will noticeably maximize your driving experience.

We shall review K7J tuning and report on the ultimate modifications for your car.

History, Power & Specs of the K7J Engine

KJ7 55 kW 75 PS 74 hp 5500 rpm

  • K7J 700
  • K7J 710
  • K7J 714 LPG E4

Dacia Logan Dacia Sandero

Tuning the Renault K7J and best K7J performance parts.

Best K7J mods

When talking about the greatest modifications for your K7J engine, we are going to concentrate on the mods that give the best power gain for you money.

Altering your K7J camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

Fast road cams usually increase the torque through the rev band, you may sacrifice a little low end power but the higher rpm power will be higher.

Competition cams, increase the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

For a road car must carefully try to optimize your engines power to your usage of the car.

You'll never have found a K7J Motorsport and race cam is a pleasure to live with when driving in heavy traffic. The low end idle will be very lumpy and irregular, so something you would notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers lamenting their decision to add an extreme competition cam profile to their engine.

Some K7J engines respond better to extreme cam durations so set your engine up on a rolling road.

The ECU mapping and injectors and fuel pump also will make differences on the bhp gains you'll get.

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.

Please watch our video which covers the 5 principles of tuning your car. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your K7J

  1. ECU Tunes - A Remapped K7J ECU provides the most power in terms of cost, replacment ECUs, and Tuning boxes are all alternatives.
  2. Upgrades to turbochargers and superchargers - A New Turbo is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. Typically one of the most costly upgrades but provides the best gains.
  3. Fast road cams are one of the most significant mechanical changes, but they must be setup by someone who knows what they are doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  4. Intake and Sports Exhausts - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

K7J Tuning Stages

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

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

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

Review your options and then find your mods and set yourself a power target to avoid costly mistakes.

ECU flashing will help to establish the full potential of all the upgrades you've done to your K7J.

(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 usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but your results usually depend much on the upgrades you've carried out and the condition of your engine.

Feeding more air and fuel into the K7J engine is the whole point to any performance tuning task.

Intake manifolds take the air during the suck phase from the intake filter and allow it to be drawn into the engine cylinders with fuel for the squish phase.

The bore size, shape and flow characteristics of the Plenum can make a big change to fuel atomisation and engine efficiency on the K7J.

It's not uncommon that plenum chambers are in desperate need of a performance upgrade, although some manufacturers provide fairly well optimized plenum chambers.

Fitting big valve kits, carrying out port work and head flowing will also raise bhp and torque, & importantly will make space for a greater bhp and torque increase on other upgrades.

K7J 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 K7J

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes superb power gains.

If a car is fitted with a turbo upgrades are giving better power gains and you will discover turbo charged engines are built using strengthened components.

However every engines will need better parts at higher power limits.See where you'll find these limits and install better quality crank and pistons to survive the power.

We see many mechanics spending a loads of money on turbo charger upgrades on the K7J only to suffer the humiliation of seeing the K7J literally blow up soon after it's used in anger.

Large capacity turbo chargers tend to experience a bottom end lag, and low capacity turbo chargers spool up more quickly but don't have the peak end power band gains.

We are pleased that the range of turbo chargers is always increasing and we are seeing variable vane turbo chargers, where the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbo chargers divert the exhaust flow into a couple of channels and flow these at differently angled vanes in the turbocharger. They also help the scavenging effect of the engine.

It is not unusual that there is a limit in the air flow sensor (AFM/MAF/MAP) on the K7J when considerably more air is being sucked into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although more complex to setup. We have this guide to twinchargers if you want to read more.

Fuelling

When you boost the bhp and torque you will need to uprate to the fuelling.

More bhp and torque needs more fuel. It makes sense to be generous with your injector capacity.

The accepted safe increase is to add 20% to the flow rate when buying an injector, this allows for injector deterioration and affords 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.

K7J Performance Exhausts

Only look to replace your exhaust if the current exhaust is creating a restriction.

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

Sports exhausts can help balance the flow of air through the engine.

But if your exhaust is too big, ie: over 2.5 inches bore, you will lose much of the flow rate and end up lacking power and torque.

Usual exhaust restrictions can be traced to the emissions filters installed, so adding a higher flowing performance catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weak spots, Issues & problem areas on the K7J

The K7J 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 K7J, 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 K7J engine please join us in our car forums where you can discuss K7J tuning options in more detail with our K7J owners. It would also be worth reading our unbiased Renault tuning articles to get insights into each modification and how effective they will be for your car.

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 K7J tuning guides which get regular updates and revisions.

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