The Lowdown on "SR18DE Modifications"

How to modify and upgrade the Nissan SR18DE

"Comprehensive guide to performance parts and tuning the Nissan SR18DE engine!"

Forums like the one at TorqueCars are frequently getting emails asking about how to improve the SR18DE from people wanting to know what are the best SR18DE power upgrades. So let us look into Nissan SR18DE upgrades and outline the best modifications on this great engine and point out some common pitfalls along the way.

The Nissan SR18DE make a good tuning project and with the optimum performance mods like ECU maps, turbo improvements and camshafts you will maximize your driving enjoyment.

Let us outline options for your SR18DE tuning and point out the optimum modifications.

The greatest SR18DE parts on an engine are in our opinion the ones that give the best power gain for your hard earned cash.

We won't be swayed by popular SR18DE parts, they need to be cost effective.

Improving air intake on the SR18DE

You need fuel and air for an engine to work. If there is a lack of 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 air into the SR18DE engine is the aim to any tuning project.

It is not unusual that there's a limit in the air flow sensor AFM/MAP on the SR18DE when loads 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 was restricting torque at a much lower level.

Intake manifolds flow the on the suck phase from the intake filter and allow it to be sucked into the engine and mixed with fuel.

The shape and flow characteristics of the Plenum can make a substantial improvement to fuel atomisation and engine efficiency on the SR18DE.

Many mass produced engine plenum chambers are improved through aftermarket tuning parts, although a few manufacturers provide fairly well optimized plenum chambers.

Big valve conversions on the SR18DE, doing a bit of 3 or 5 angle valve jobs and porting and head flowing will also increase bhp and torque, the fantastic side effect is it will allow you to get raising the bhp and torque increase on other tuning parts.

SR18DE performance cam tips.

Each engine responds better to mild camshaft durations so set your engine up on a rolling road.

The map and fuel pump and injectors also have a large bearing on the bhp gains you'll make.

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.

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

NB: Fast road cams tend to raise the bhp and torque across the rpm band, you may lose a little low end torque but high end rpm power will be better.

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

A Competition camshaft will just annoy you whilst in heavy traffic.

You should ideally match your torque band to your usage of the car so for a typical daily driver stick with a fast road SR18DE camshaft

Stage 1, 2 and 3 mods for the SR18DE

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 SR18DE parts:

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

Stage 2 SR18DE parts:

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

Stage 3 SR18DE parts:

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

Remapping should help to to establish the full potential of all the parts you've done to your SR18DE.

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 differs on the parts you've carried out and the condition of your engine.

Turbo modifications on the SR18DE

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 SR18DE.

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 motor is fitted with a turbocharger tuning mods are simpler to install and most turbo charged engines use strengthened components.

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

It is important to find these limitations and fit stronger pistons, crank and engine components to handle the power.

There are many mechanics spending a loads on turbo charger upgrades on the SR18DE only to have the car catastrophically fail on it's first outing after it's finished.

Big capacity turbochargers often experience low end lag, and low capacity turbochargers spool up much more quickly but do not have the high rpm bhp gains.

Over the last 20 years the choice of turbo units is always moving on and we now see 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 designed vanes in the turbocharger. 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 performance gains, although more challenging to get working. We have this feature on twinchargers if you want to read more.

Tips about fuel supply on the SR18DE

Don't forget to look at the fuelling when you are increasing the power - it makes the car more thirsty. Experienced tuners recommend to be generous with your injectors flow rate.

The accepted safe increase is to add another 15% when fitting an injector, helps cope with injector deterioration and provides 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 SR18DE performance exhaust upgrades

The only time you should look to upgrade your exhaust system with an upgraded one is if your exhaust is actually causing a restriction in flow.

On most factory exhausts you'll see the 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 can usually air flow from the engine but avoid an exhaust that is too big or you may end up will reduce the flow rate. Stick to one and a half to two and half inches for best results.

Usual exhaust restrictions can be traced to the catalyst installed, so adding a freer flowing race alternative will help avoid this restriction.

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

Faults issues and things to look out for on the SR18DE

Like most engines an SR18DE, 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 SR18DE, failure to do this will exacerbate engine wear, on a tuned SR18DE 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 SR18DE why not pop over to the forums at TorqueCars where you can chat about SR18DE tuning options and read about others projects who may be planning to do similar modifications on their SR18DE.

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This entry was posted under Makes and Models. Tags: engine, nissan
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