Modding uprating the Renault K4M engine!

All you need to know about "K4M Modifications"

K4M Modifications Guide

How to modify and upgrade the Renault K4M

"Comprehensive guide to tuning and performance parts on the Renault K4M engine!"

Popular tuning sites like TorqueCars are regularly getting messages asking about how to improve the K4M from people inquiring about getting more power from the K4M and wanting to know what are the optimum K4M power upgrades. So let us look into Renault K4M parts and outline the best modifications on this great engine and point out some frequent tuning mistakes along the way.

The Renault K4M make awesome project engines and with the right sports parts like ECU maps, turbo kits and camshafts you will positively maximise your driving pleasure.

In this article we provide a guide to K4M tuning and summarise the optimum mods that work.

The ultimate K4M tuning parts on an engine are as we have found the ones that give the best gains for your money.

We won't be swayed by popular K4M tuning parts, they need to be cost effective.

K4M induction kits

Improving air intake on the K4M

You need air matched to fuel for an engine to work. If there is insufficient fuel then it will run lean, if there is not enough air it runs rich losing power which risks damage to the K4M. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pulling more fuel and air into each cylinder is the primary aim to any engine performance tuning job.

It is not unusual that there is a restriction in the air flow sensor MAP/MAF/AFM on the K4M when a lot 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 sapped performance at a much lower level.

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

Structure and flow rate of the Plenum can make a big effect on to fuel atomisation and engine efficiency on the K4M.

I usually find headers are crying out for a performance upgrade, although a few manufacturers provide decently flowing headers.

Big valve conversions on the K4M, getting 3 or 5 angle valve jobs and porting and head flowing will also raise torque, this will afford you raising the torque increase on other upgrades.

K4M performance cam tips.

Each engine responds better to extreme camshaft durations so view each engine as unique.

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

Longer 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.

Altering your K4M cam will make a dramatic difference to the engine power band. Choosing a higher performance cam profile raises the power band accordingly.

NB: Fast road cams normally boost the bhp across the rpm range, you might lose a little low down bhp but your top end will be lifted.

Motorsport cams, boost the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Competition camshaft is not great driving in heavy traffic.

You should ideally match your power band to your cars usage so for a car used daily stick with a fast road K4M camshaft

Stage 1, 2 and 3 mods for the K4M

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 K4M parts:

Drilled & smoothed airbox, Fast road camshaft, Sports exhaust manifold, Remaps/piggy back ECU, Panel air filters, Intake headers.

Stage 2 K4M parts:

fuel pump upgrades, Fast road cam, Ported and polished head, Sports catalyst & performance exhaust, induction kit, high flow fuel injectors.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 3 K4M parts:

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

Review your options and then find your mods and set yourself a power target to save yourself from expensive mistakes.

Mapping should help to unlock the full potential of all the parts you've done to your K4M.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage usually rely on the parts you've fitted and the condition of your engine.

Turbo modifications on the K4M

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the K4M.

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 motor has a turbocharger upgrades are going to make more power and most turbo engines are made with harder and stronger components.

However you will find an engines will need better parts at higher power limits

See where you'll find these limitations and fit stronger pistons, crank and engine components to survive the power.

It's not unheard of mechanics spending a lots of money on turbo upgrades on the K4M only to experience the engine explode just after it's been completed.

Large capacity turbos tend to suffer a bottom end lag, and low capacity turbos spool up really quickly but don't have the peak end torque gains.

Thankfully the choice of turbo chargers is always developing and we now see variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

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

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp gains, although more challenging to configure. We have this guide to twinchargers if you want to read more.

Tips about fuel supply on the K4M

Don't overlook the need to pay attention to the fuel system when you are increasing the power - it makes the car more thirsty. Care modifiers usually say to over specify your flow rate on the injectors.

The accepted safe increase is to add 20% when specifying an injector, this takes into account injector deterioration and provides a bit of spare capacity should the engine require more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended K4M performance exhaust upgrades

The only time you should look to uprate your exhaust system with an upgraded one is if your current exhaust is creating a flow problem.

On most factory exhausts you'll see your flow rate is still ok even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Please dont run with the largest exhaust you can find this will slow the exhaust rate - the best exhausts for power gains are usually between one and a half to two and half inches. Your exhaust design, the bend angles and construction are what have more effect on flow rates than your pipe width to a certain extent. So the exhaust design is a big factor.

Typically exhaust restrictions can be traced to the catalysts installed, so adding a freer flowing sports alternative will help avoid this restriction.

Catalyst removal (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the K4M

Like most engines an K4M, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the K4M, failure to do this will exacerbate engine wear, on a tuned K4M this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your K4M why not pop over to the forums at TorqueCars where you can chat about K4M tuning options and read about others projects who may be planning to do similar modifications on their K4M.

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