Tuning Feature: Nissan RB25DE Modified

"Comprehensive guide to tuning and performance parts on the Nissan RB25DE engine!"

We are frequently getting messages requesting info on the greatest RB25DE power 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.

The Nissan RB25DE make awesome project engines and with a few sensible motorsport upgrades like remaps, turbo improvements and camshafts you will certainly improve your driving enjoyment.

Let us look at RB25DE tuning and provide tips on the premier modifications.

The best RB25DE parts on an engine are usually the ones that give the best value for money.

We won't be swayed by popular RB25DE parts, they need to be cost effective.

Altering your RB25DE cam could make a dramatic difference to your engines power band. Choosing a higher performance cam profile raises the power band accordingly

NB: Fast road camshafts tend to raise the bhp through the rev range, you could sacrifice a little low down power but top end will be lifted.

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

A Motorsport camshaft is not great in heavy traffic.

You should ideally optimize your power band to your cars usage so for a road car stick with a shorter duration RB25DE camshaft

Different RB25DE engines respond better to different cam durations than others.

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

Extending exhaust or intake 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.

RB25DE Tuning Stages

Stage 1 RB25DE modifications: Sports exhaust manifold, Remaps/piggy back ECU, Intake headers, Panel air filters, Fast road camshaft, Drilled & smoothed airbox.

Stage 2 RB25DE modifications: high flow fuel injectors, Sports catalyst & performance exhaust, Ported and polished head, fuel pump upgrades, Fast road cam, induction kit.

Stage 3 RB25DE modifications: Crank and Piston upgrades to alter compression, Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam, Internal engine upgrades (head flowing porting/bigger valves).

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

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but figures achieved usually vary depending on the parts you've done and the condition of your engine.

It is the main goal to any engine modification task to force fuel and air into each cylinder

Intake manifold take the air from the air filter and allow it to be drawn into the engine and mixed with fuel.

Structure and rate of flow of the Intake manifold can make a big improvement to fuel atomisation on the RB25DE.

Most headers are needing motorsport parts, although a few makers provide decently flowing headers.

Big valve conversions on the RB25DE, getting 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 modifications.

Turbo upgrades for the RB25DE

NASP 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 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 superb power gains.

When an engine is fitted with a turbo parts are relatively easy and we find turbo engines use better components.

There are practical limits for every engine, with some being over specified and some just sufficiently able to handle stock power

We recommend you find these restrictions and fit forged components to cope with the power.

We see many drivers spending a a stack of money on turbo charger upgrades on the RB25DE only to suffer the humiliation of seeing the car explode on it's first outing after it's been finished.

Bigger capacity turbos often suffer a bottom end lag, and small turbos spool up really quickly but won't have the peak end engines power gains.

We are pleased that the world of turbo units is always moving on and we now see variable vane turbo units, permitting the vane angle is altered according to speed to lower lag and increase top end performance.

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

It is common that there's a limitation in the air flow sensor MAF/MAP on the RB25DE when a lot 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 was restricting bhp at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although more complex to install. We have this in depth look at twinchargers if you want to read more.

Uprating RB25DE fuel injectors

Don't forget to ramp up the fuel delivery when you are increasing the torque - it makes the car more thirsty. It is important to over specify your flow rate on the injectors.

The accepted safe increase is to add 20% when fitting an injector, which takes into account injector deterioration and provides you some spare capacity should the engine require 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.

Best RB25DE performance exhausts

Only look to increase your exhaust if the current exhaust is actually causing a flow problem.

On most factory exhausts you should find that the flow rate is ok 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 equal out the flow of air through the engine.

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

Common exhaust restrictions come around the filters installed, so adding a freer flowing high performance alternative will help avoid this restriction.

Problems and issues to look out for on the RB25DE

The RB25DE engines, if regularly serviced and maintained, are generally very reliable and have few issues. {But if neglected they can cost a small fortune|When neglected they get very expensive to run|They can however be quite expensive if neglected| }

Regular oil changes are vital on the RB25DE, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your RB25DE engine please join us in our friendly forum where you can discuss tuning options in more detail with our RB25DE owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Nissan. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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