Modding uprating the Nissan YD25DDTi engine!

Modifying and improving: "YD25DDTi Modifications"

YD25DDTi Modifications Guide

How to modify and upgrade the Nissan YD25DDTi

"Comprehensive guide to performance tuning the Nissan YD25DDTi engine!"

Sites like TorqueCars often are getting posts asking how to improve the YD25DDTi from people inquiring about getting more power from the YD25DDTi and wanting to know what are the premier YD25DDTi modifications. So let us look into Nissan YD25DDTi mods 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 look into YD25DDTi tuning and summarise the greatest mods that work. Nissan YD25DDTi make awesome project engines and with the best sports modifications like ECU maps, turbo improvements and camshafts you will really maximise your driving pleasure.

When talking about the top parts for your YD25DDTi engine, we are going to concentrate on the upgrades that give the best power gain for you money.

YD25DDTi induction kits

Improving air intake on the YD25DDTi

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

So Forcing more air and fuel into each cylinder is vital to any tuning project.

It is not unusual that there's a limit in the air flow sensor AFM/MAF on the YD25DDTi when a lot more air is being sucked into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor limited bhp and torque at a much lower level.

Air Intake manifolds transmit the on the suck phase from the filter and allow it to be drawn into the engine and mixed with fuel.

The size of bore and shape and flow rate of the Air Intake manifolds can make a large difference to to fuel mixing and power on the YD25DDTi.

Many mass produced engine intake manifold are in dire need of a performance upgrade, although a few OEM provide fairly well optimized intake manifold.

Increasing the YD25DDTi valve size, carrying out 3 or 5 angle valve jobs and porting and head flowing will also raise bhp and torque, and more importantly will afford you increasing the bhp and torque increase on other upgrades.

YD25DDTi performance cam tips.

Different YD25DDTi engines respond better to mild camshaft durations so set your engine up on a rolling road.

The ecu map and injectors and fuel pump also will say much on the bhp gains you'll make.

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 YD25DDTi camshaft will make a dramatic difference to the engine torque. Choosing a higher performance camshaft profile raises the torque accordingly.

NB: Fast road camshafts usually raise the bhp and torque across the rpm range, you could drop a little low end bhp but the high end rpm power will be higher.

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

On a daily driver you should ideally to optimize your bhp range to your driving style.

You will never have ever thought a YD25DDTi Motorsport and race cam is a pleasure to live with when in heavy traffic.

Stage 1, 2 and 3 mods for the YD25DDTi

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 YD25DDTi parts:

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

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

Stage 2 YD25DDTi parts:

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

Stage 3 YD25DDTi parts:

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

Review your options and then source your mods and set yourself a power target to avoid disappointment.

A remap will help unlock the full potential of all the mods you've done to your YD25DDTi.

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 power output will rely on the mods you've applied and the condition of your engine.

Turbo modifications on the YD25DDTi

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 YD25DDTi.

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.

If a car has forced induction tuning parts are going to make more power and we find turbo charged engines are built with stronger components.

However most engines will have power limits

We recommend you find these limitations and upgrade to more solid crank and pistons to cope with the power.

It's not unheard of people spending a lots of money on turbo upgrades on the YD25DDTi only to see the engine block go up in smoke on it's first outing after it's completed.

Bigger turbo chargers commonly suffer low end lag, and little turbo chargers spool up much more quickly but won't have the high rpm power band gains.

In recent times the selection of turbo chargers is always increasing and we commonly find variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end power.

Twin scroll turbo chargers divert the exhaust gases into two channels and direct these at differently designed vanes in the turbo charger. They also boost 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 and torque gains, although more challenging to setup. We have this article on twincharging if you want to read more.

Tips about fuel supply on the YD25DDTi

When you increase the torque you will need to pay attention to to the fuelling.

More torque needs more fuel. Most tuners we speak with say to over specify your injector capacity.

As a rule of thumb add 20% when buying an injector, which takes into account injector deterioration and allows 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 YD25DDTi performance exhaust upgrades

We'd only recommend you look to increase your exhaust system with an upgraded one is if your current exhaust is actually causing a restriction in flow.

On most factory exhausts you'll see the exhaust flow rate is still fine 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 will certainly help air flow through the engine but do not go too wide or you may end up will reduce the flow rate. Stick to one and a half to two and half inches for best results.

Typically exhaust restrictions are traced to the catalyst installed, so adding a higher flowing performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the YD25DDTi

Like most engines an YD25DDTi, 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 YD25DDTi, failure to do this will exacerbate engine wear, on a tuned YD25DDTi 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 YD25DDTi why not pop over to the forums at TorqueCars where you can chat about YD25DDTi tuning options and read about others projects who may be planning to do similar modifications on their YD25DDTi.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We want to know your experiences with upgrades on your YD25DDTi, it helps us improve our tips and keeps us current so please use the comments box to drop a tip.

If you liked this page please share it with your friends, drop a link to it in your favourite forum or use the bookmarking options to save it to your social media profile.

Check out TorqueCars new YouTube channel, and see their awesome new content...


Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article