Modding tuning and best performance upgrades on the Nissan RB25DE engine!

Explore RB25DE Modifications"

How to modify and upgrade the Nissan RB25DE

"Comprehensive guide to tuning the Nissan RB25DE engine!"

Forums like the one at TorqueCars are always getting messages requesting information on how to improve the RB25DE from people inquiring about getting more power from the RB25DE and wanting to know what are the optimum RB25DE upgrades. So let us look into Nissan RB25DE parts and outline the best mods that work on this great engine and point out some common pitfalls along the way.

Our aim here is to consider RB25DE tuning and outline the best modifications for your car. Nissan RB25DE have loads of potential and with the optimum uprated upgrades like remapping, turbo kits and camshafts you will certainly maximise your driving experience.

When talking about the top parts for your RB25DE engine, we are going to focus on the ones that give the best power gain for you money.

RB25DE induction kits

Improving air intake on the RB25DE

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

So it's important to any engine tuning task to shove more air and fuel into the RB25DE engine but this has a knock on effect with the air flow sensor.

You'll commonly see there's a limit in the air flow sensor MAP/MAF/AFM on the RB25DE when considerably more air is being fed into the engine.

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

Engines intake headers flow the on the suck phase from the filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

Shape and flow rate of the Headers can make a big difference to to fuel delivery on the RB25DE.

I usually find intake manifold are ripe for aftermarket tuning parts, although some car makers provide well optimised intake manifold.

Fitting big valve kits, doing some 3 or 5 angle valve jobs and porting and head flowing will also increase bhp, & more importantly will give you an improved bhp increase on other tuning parts.

RB25DE performance cam tips.

Different RB25DE engines respond better to less aggressive camshaft durations check your engine on a rolling road.

The engine timing and fuelling also have a large bearing on the torque gains you'll hit.

Longer valve durations can alter the torque 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.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen cam profile, so large bhp gains are on offer for cam upgrades.

NB: Fast road camshafts normally bump the torque throughout the rpm range, you may lose a little bottom end power but the top end will improve.

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

On a daily driver you must carefully try to match your torque band to your usage of the car.

I'd never have ever thought a RB25DE Competition camshaft is a pleasure to live with when on the daily commute.

Stage 1, 2 and 3 mods for the RB25DE

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 RB25DE parts:

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

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

Stage 2 RB25DE parts:

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

Stage 3 RB25DE parts:

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

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

A remap helps fully realize the full potential of all the upgrades you've done to your RB25DE.

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 figures achieved will rely on the upgrades you've applied and the condition of your engine.

Turbo modifications on the RB25DE

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 RB25DE.

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

When your car is turbo charged upgrades are more reliable and we find turbo engines are built with uprated components.

However engines have limits

Discover these limitations and upgrade to more solid crank and pistons to cope with the power.

There are many car owners spending a a stack of money on turbo upgrades on the RB25DE only to suffer the humiliation of seeing the RB25DE catastrophically fail soon after it's been completed.

Big capacity turbo units commonly experience a bottom end lag, and little turbo units spool up really quickly but won't have the peak rpm power band gains.

In recent times the world of turbo units is always moving on and we commonly find variable vane turbo units, where the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo units divert the exhaust flow into two channels and feed these at differently profiled vanes in the turbo charger. They also increase the scavenging effect of the engine.

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

Tips about fuel supply on the RB25DE

Don't dismiss the need boost the fuelling when you are increasing the performance - it makes the car more thirsty. Don't forget to over specify your flow rate on the injectors.

The accepted safe increase is to add another 15% when fitting an injector, this accounts for injector deterioration and gives 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 RB25DE performance exhaust upgrades

You only need to to upgrade your exhaust system with an upgraded one is if your exhaust is creating a restriction.

On most factory exhausts you should find that the flow rate is still good 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.

Sports exhausts can usually air flow out of the engine but avoid an exhaust that is too big or you could will reduce the flow rate. Stick to one and a half to two and half inches for best results.

Typically exhaust restrictions can be located the catalyst and filters installed, so adding a higher 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 RB25DE

Like most engines an RB25DE, 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 RB25DE, failure to do this will exacerbate engine wear, on a tuned RB25DE 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 RB25DE why not pop over to the forums at TorqueCars where you can chat about RB25DE tuning options and read about others projects who may be planning to do similar modifications on their RB25DE.

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