Modding upgrading and tuning the Nissan YD25DDT engine!

All you need to know about "YD25DDT Modifications"

YD25DDT Modifications Guide

How to modify and upgrade the Nissan YD25DDT

"Comprehensive guide to tuning the Nissan YD25DDT engine!"

Popular tuning sites like TorqueCars are always getting emails requesting information on how to improve the YD25DDT from people wanting to know what are the premier YD25DDT mods that work. So let us look into Nissan YD25DDT modifications and outline the best mods that work on this great engine and point out some common pitfalls along the way.

The Nissan YD25DDT have loads of potential and with the best uprated upgrades like remaps, turbo upgrades and camshafts you will substantially improve your driving experience.

Let us review and look at YD25DDT tuning and summarise the ultimate modifications for your car.

Just because particular tuning mods are appear in lots of YD25DDT projects it doesn't mean its worth having, instead we'll focus on the best tuning mods that will give your YD25DDT the best power gain for you spend.

Without us subscribing to the misaprehension of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

YD25DDT induction kits

Improving air intake on the YD25DDT

You need air and fuel for an engine to work. If there is little supply of fuel then it will run lean, if there is a lack of air it runs rich losing power and potentially damaging the engine. 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 modification project to feed air and fuel into the YD25DDT engine but this has a knock on effect with the air flow sensor.

It is not unusual that there is a limitation in the air flow sensor MAP/MAF/AFM on the YD25DDT when a lot more air is being drawn into the engine.

We see 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped torque at a much lower level.

The intake plenum take the on the suck phase from the air cleaner and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and rate of flow of the Plenum can make a noticeable difference to to fuel delivery on the YD25DDT.

Most intake manifold are in dire need of performance upgrades, although a few OEM provide fairly well optimized intake manifold.

Fitting big valve kits, carrying out port matching and head flowing will also boost bhp and torque, the fantastic side effect is it will afford you a greater bhp and torque increase on other mods.

YD25DDT performance cam tips.

Each engine responds better to less aggressive cam durations than others.

The ECU mapping and fuel pump and injectors also will say much on the power gains you'll achieve.

Longer valve durations can alter the power 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 YD25DDT camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

NB: Fast road camshafts commonly increase the torque across the rev band, you could drop a little low end power but higher rpm power will be higher.

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

A Race camshaft will just annoy you whilst driving in heavy traffic.

You should ideally match your bhp range to your driving style so for a typical daily driver stick with a shorter duration YD25DDT camshaft

Stage 1, 2 and 3 mods for the YD25DDT

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 YD25DDT parts:

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

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

Stage 2 YD25DDT parts:

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

Stage 3 YD25DDT parts:

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

The YD25DDT engine blocks are great to work on and we note that there is an increase of upgrades and tuning parts about.

ECU flashing helps release the full potential of all the upgrades you've done to your YD25DDT.

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 may differs on the upgrades you've applied and the condition of your engine.

Turbo modifications on the YD25DDT

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 YD25DDT.

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

When the engine is fitted with a turbocharger tuning mods are giving better power gains and you'll see that turbo engines are made with uprated components.

However you'll find engines will have power limits

Research these limits and install better quality crank and pistons to handle the power.

There are many drivers spending a lots of money on turbo charger upgrades on the YD25DDT only to suffer the humiliation of seeing the YD25DDT throw a rod soon after it's used in anger.

Larger turbo units tend to experience low end lag, and smaller turbo units spool up more quickly but do not have the peak end torque gains.

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

Twin scroll turbo units divert the exhaust flow into two channels and direct these at differently angled vanes in the turbo. 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 bhp gains, although more difficult to get working. We have this article on twincharging if you want to read more.

Tips about fuel supply on the YD25DDT

When you increase the power you will need to look at to the fuel system.

More power needs more fuel. Experienced mechanics will tell you to over specify your injector capacity.

The rule of thumb is to add another 20% when fitting 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 YD25DDT performance exhaust upgrades

The only time you should look to boost your exhaust system with an upgraded one is if the current exhaust is actually creating a restriction in flow.

On most factory exhausts you'll see 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 through the engine but avoid an exhaust that is too wide or you may end up will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Usual exhaust restrictions can be traced to the filters installed, so adding a faster flowing high performance alternative will help avoid this restriction.

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

Faults issues and things to look out for on the YD25DDT

Like most engines an YD25DDT, 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 YD25DDT, failure to do this will exacerbate engine wear, on a tuned YD25DDT 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 YD25DDT why not pop over to the forums at TorqueCars where you can chat about YD25DDT tuning options and read about others projects who may be planning to do similar modifications on their YD25DDT.

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 parts on your YD25DDT, 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