Car tuning tips:PR25DD Modifications"

PR25DD Modifications Guide

How to modify and upgrade the Nissan PR25DD

"Comprehensive guide to performance parts and tuning the Nissan PR25DD engine!"

Popular tuning sites like TorqueCars are frequently getting emails asking how to improve the PR25DD from people wanting to know what are the optimum PR25DD modifications. So let us look into Nissan PR25DD parts and outline the best modifications on this great engine and point out some frequent tuning mistakes along the way.

The Nissan PR25DD offer good returns when tuned and with carefully chosen sports tuning mods like a remap, turbo upgrades and camshafts you will positively maximise your driving opportunities.

Our aim here is to look at PR25DD tuning and point out the optimum modifications for your car.

The best PR25DD parts on an engine are obviously the ones that give the biggest return for your money.

We won't be swayed by popular PR25DD parts, they need to be cost effective.

PR25DD induction kits

Improving air intake on the PR25DD

You need air matched to fuel for an engine to work. If there is insufficient fuel then it will run lean, if there is too little air it runs rich sapping power which risks damage to the PR25DD. We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the primary aim to any engine performance tuning job to pull more air and fuel into your PR25DD but this has a knock on effect with the air flow sensor.

It is not unusual that there is a limit in the air flow sensor MAF/MAP on the PR25DD when loads more air is being fed into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited power at a much lower level.

The intake plenum take the air from the intake filter and allow it to be fed into the engine and mixed with fuel.

Structure and flow characteristics of the air Intake manifold can make a noticeable effect on to fuel engine efficiency on the PR25DD.

It's not uncommon that intake headers are needing motorsport parts, although a few manufacturers provide well optimised intake headers.

Fitting big valve kits, carrying out 3 or 5 angle valve jobs and porting and head flowing will also raise torque, and importantly will make space for an improved torque increase on other modifications.

PR25DD performance cam tips.

Different PR25DD engines respond better to less aggressive cam durations so set your engine up on a rolling road.

The engine timing and fuelling also will make differences on the bhp gains you'll hit.

Altering 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 PR25DD cam will make a dramatic difference to the engine torque. Choosing a higher performance cam profile raises the torque accordingly.

NB: Fast road camshafts usually push up the torque through the rpm range, you might lose a little bottom end torque but high end rpm power will be better.

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

For a daily driver you should ideally to match your engines power to your preferences.

I'd be gobsmaked if you have found a PR25DD Motorsport camshaft is a pleasure to live with when on the daily commute.

Stage 1, 2 and 3 mods for the PR25DD

Stage 1 PR25DD parts:

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

Stage 2 PR25DD parts:

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

Stage 3 PR25DD parts:

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), Competition cam.

The PR25DD units are great to work on and we're finding that there are increasing numbers of upgrades and tuning parts around.

Remaps will help fully realize the full potential of all the modifications you've done to your PR25DD.

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 results often depend much on the modifications you've carried out and the condition of your engine.

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

Turbo modifications on the PR25DD

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 PR25DD.

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 your car has a turbocharger upgrades are going to make more power and turbo engines are built with harder and stronger components.

However you'll find engines will have power limits

See where you'll find these limitations and install better quality components to cope with the power.

There are many mechanics spending a loads on turbo upgrades on the PR25DD only to experience the whole thing go up in smoke soon after it's used on the roads.

Larger capacity turbochargers tend to suffer a bottom end lag, and low capacity turbochargers spool up much more quickly but won't have the peak rpm bhp gains.

Over the last 20 years the range of turbochargers is always increasing and we are seeing variable vane turbochargers, permitting the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbochargers divert the exhaust flow into 2 channels and push these at differently designed 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 torque gains, although more complex to setup. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the PR25DD

When you improve the bhp you will need to uprate to the fuel delivery.

More bhp needs more fuel. We would recommend you to over specify your injectors flow rate.

The rule of thumb is to add 20% to the flow rate when specifying an injector, which takes into account injector deterioration and provides you some 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 PR25DD performance exhaust upgrades

Only look to replace your exhaust system with an upgraded one is if the current exhaust is actually creating a restriction.

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

Note that with the largest exhaust you can find this will reduce the exhaust flow 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 are traced to the emissions filters 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 PR25DD

Like most engines an PR25DD, 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 PR25DD, failure to do this will exacerbate engine wear, on a tuned PR25DD 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 PR25DD why not pop over to the forums at TorqueCars where you can chat about PR25DD tuning options and read about others projects who may be planning to do similar modifications on their PR25DD.

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