Nissan SR20DET engine modification guide

SR20DET has lots of potential for your tuning project."

The SR20DET is a fantastically tunable engine from Nissan and is extremely strong and reliable.

Based around a light alloy block with alloy heads the twin cam setup uses tried and tested parts and the relatively recent T28 turbo and intercooler made the engine stand out among it’s peers.

Production started in 1989 where it was insitially transversely mounted. Later the engine was rotated to a longitudinal setup which work best for the many rear wheel drive cars Nissan planned to produce.

It was fitted to a wide range of cars and is frequently used in motor sport applications. Most people see power figures of 300bhp on stock internals with relatively simple turbo and fuelling upgrades.

If you just want a cheap easy large power boost on your standard SR20DET tuning project, all you have to do is fit a boost controller and nitrous kit. Most of our members are looking to add parts over time rather than take the car off the road for 6 months for a complete overhaul and the SR20DET is able to offer this upgrade route.

  • S13 Black top - (Garrett T25G turbo)
  • S13 Red top -  (Garrett T25G turbo) 370cc injectors were used.
  • S14 Black top -Variable Cam Timing or VCT was introduced on the intake cam (Garrett T28 journal bearing turbo for Australian and Eu markets and Garrett T28 Ball Bearing turbo for the Japanese market 370cc injectors were used.
  • S15 Black top -  VCT, 6-speed manual transmission (Garrett Journal Bearing T28 for Eu and Australia and Ball Bearing T28 turbo for Japan)
  • W11 & N30 Silver top - Garrett T25G turbo & Garrett T25BB Ball Bearing 9psi - 227hp for Japan

Later engines are always an improvement over earlier models, with various revisions and enhancements introduced. 1995 saw the “bent cam” (named after the curve of the rocker cover at the back which makes it look bent) introduced on the 200sx which saw the introduction of variable valve timing control VTC but also nicknamed VVT in some regions, addition of the Garrett T28 turbo and uprated injectors.

The stock engine will reportedly tolerate power figures of 350-400bhp with some reporting failures of the sleeves around 475bhp indicating that some lucky owners have a block which can cope with more than 400bhp reliably.

Plan your power targets before you begin. Is the car going to be used as your daily drive or is your desire for a competition ready car? If you do your upgrades in the right order you’ll keep the car drivable and can spread your upgrade costs.

Best SR20 DET mods

When talking about the best best for your SR20 DET engine, we are going to concentrate on the upgrades that give the best value for money.

Altering your SR20 DET camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

The cam profile makes a large difference and fitting vernier pulleys will allow fine control and put the power band exactly where you need it to match your gearing. Avoid pairing a light weight single mass flywheel with an aggressive cam profile or you’ll end up with a very lumpy engine.

Fast road camshafts normally increase the bhp and torque throughout the rpm range, you could sacrifice a little low down bhp but high end rpm power will be higher.

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

A Motorsport cam will just annoy you whilst in heavy traffic.

You should ideally optimize your engines power to your preferences so for a car used daily stick with a shorter duration SR20 DET cam

Plan your SR20DET tuning project carefully, decide on your power target and then uprate the components to get your there.

Exhaust and fuelling upgrades are a good base to start with, but you’ll not notice much more power until you start tweaking the boost and timing.

The fuel pump upgrade makes a lot of sense when you increase the power as the stock fuel pump does not flow that much fuel (140 liters per hour) and tops out around the 390bhp mark. 550cc fuel injectors give plenty of tuning potential.

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

The stock MAF sensor is good for 300bhp, any more power than this and you should upgrade the MAF (the 300zx MAF is a good option here for a cheap upgrade) or if you are targeting much higher power gains, then upgrade to a MAP sensor.

It is always best to overshoot your fuel requirement a little to give you a little more tuning headroom and as a bonus you’ll improve reliability. There is little point going mad with the injectors and fuel pump capacity if you are only seeking modest gains as your tuning budget is best used elsewhere.

4 Cylinder turbocharged engines assuming a 20% overhead to work with..

  • 58 PSI 340cc/min 200hp
  • 58 PSI 511cc/min 300hp
  • 58 PSI 682cc/min 400hp
  • 58 PSI 1022cc/min 600hp

A longer valve duration 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.

Typical stage 1 mods often include: Intake headers, Drilled & smoothed airbox, Sports exhaust manifold, Panel air filters, Remaps/piggy back ECU, Fast road camshaft.

Typical stage 2 mods often include: high flow fuel injectors, fuel pump upgrades, Fast road cam, Sports catalyst & performance exhaust, induction kit, Ported and polished head.

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

The SR20 DET engines respond well to mods and we note that there are plenty of parts and performance parts around.

Mapping allows a tuner to release the full potential of all the parts you've fitted to your SR20 DET.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but the outcome often differs on the parts you've applied and the condition of your engine.

SR20DET performance Exhausts and intake

Smaller intercoolers suffer from heat soak, a build up of heat which is something a larger intercooler will resist. The more boost you are running the hotter the intake air will become (due to compression of air causing a temperature rise). Relocating the intercooler to the front of the car (obviously in front of the radiator) will allow more air to flow through it, and, as most are wing mounted this is a good performance upgrade to help resist heat soak. Larger intercoolers are a good upgrade option if you suffer from heat soak and the associated loss of power.

You don’t even need to go to the aftermarket suppliers if you want to keep costs down, the intercooler from higher power cars can be front mounted and give you a capacity boost.

It is the main goal to any car tuning project to feed more fuel and air into the SR20 DET engine

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

The shape and flow rate of the Intake headers can make a large difference to to fuel engine efficiency on the SR20 DET.

Most intake manifold are begging for an upgrade, although a few car makers provide well optimised intake manifold.

Adding a SR20 DET larger valve kit, carrying out 3 or 5 angle valve jobs and porting and head flowing will also improve bhp and torque, and as an added benefit will make space for a greater bhp and torque increase on other upgrades.

You may need to uprate your exhaust if your current exhaust is actually causing a flow problem.

On most factory exhausts you'll find the exhaust flow rate is still fine 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 balance the flow of air through the engine.

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

Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a higher flowing sports alternative will help avoid this restriction.

Regular maintenance on the SR20DET

Copper tipped plugs should really be changed every 6 months or 5000 miles or so on a tuned SR20DET.

The more expensive Iridium tipped plugs last longer and cope with lots of heat. Use a fully synthetic high quality oil and the engine will prove to be reliable changing this every 6000 miles with a new oil filter.

Cooling is usually a priority upgrade for SR20DET owners, with larger capacity radiators. Interestingly most opt to retain the OEM fan and fan cowling as this is quite efficient and fits nicely into the space available although it’s not the prettiest option.

Boost controllers will make a significant power gain and pared with a remap or aftermarket ECU gives you the ability to fully realise the potential of your modifications.

If fitting an aftermarket ECU to your car please ensure it is fitted with a knock sensor, as this can avoid costly repairs and we have seen too many engines destroyed when this could have been prevented.

Your car needs to be setup on a rolling road and tweaked on the fly, a hit and miss try it and see approach will take a lot longer to do right and affords more potential opportunity for things to go wrong.

Turbo upgrades for the SR20 DET

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

It's not unheard of drivers spending a lot of money on turbo upgrades on the SR20 DET only to have the engine explode just after it's completed.

Larger capacity turbochargers tend to experience a bottom end lag, and small turbochargers spool up more quickly but won't have the peak rpm power band gains.

Thanks to progress the selection of turbo chargers is always moving on and we now see variable vane turbo chargers, allowing the vane angle is altered according to speed to lower lag and increase top end torque.

We've seen some Twin turbo setups working really well on the SR20DET engine blocks and one of these used a pair of GReddy TD05-16g turbines in parallel giving 2.2 bar of boost.

It's worth looking into the newer twin scroll turbo chargers, these divert the exhaust flow into a couple of channels and flow these at differently angled vanes in the turbocharger. They also increase the scavenging effect of the engine and give good results on the SR20 DET.

You'll commonly see there is a restriction in the air flow sensor AFM/MAP on these engines when considerably more air is being drawn into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited performance at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although harder to get working. We have a Twincharger guide if you want to read more on this setup.

You can make the job of working on the engine a lot easier if you upgrade to flexible turbo oil and coolant pipes, the standard metal ones have a tendency to crack and break wreaking havoc on your engine, and every time you remove or refit a turbo this risk increases.

A general turbo tip: For performance turbos we insist on using ball bearing turbos or ceramic coated bearings, the thrust bearings suffer from noticeable lag and do not cope that well with larger performance gains as they wear.

The T28’s from the S14 provide power in the 240-280bhp range, A Nissan Sylvia turbo will offer around 300bhp so makes more sense to the power hungry.

Some of the new hybrid turbos offer wider power bands and up more quickly and deliver more power at the top end. The Garrett GT28 RS or GT2871R are extensively used by our members as upgrades on their SR20DET engines.

The GT2871R provides loads of power up the high end of the rev range, but does not suffer from low down lag so would be our recommended turbo upgrade for those seeking power figures of 320-330bhp. The SC61BB is the turbo for the serious track day user offering lots of torque and low down power.

Going beyond 300bhp

For power upto 400bhp you should be good with most T2 turbos which should usually be a straight bolt on swap with your OEM turbo.

There are many suitable T3 turbo upgrades on the market with hybrid internals. Thanks to modern profiling and optimisations, the new large capacity turbos do not suffer from turbo lag and produce power right up to the redline. Obviously you’ll need to uprate the oil feed pipes, air pipes and cooling pipes to cope with a larger turbo but the benefits outweigh the hassle when you have a good strong block like the SR20DET to work on.

Stroker kits and rebores will increase capacity to around 2.2 litres and you’ll find many kits around to achieve this.

Drop in a gas flowed head, high flow exhaust, manifold and sports catalyst (if you want to stay road legal) and you are set for higher power gains.

Fuelling will need to run at 190 liters per hour for 400bhp, if you want more than this then a 225 lph unit will get you there when mated to the right injectors (assuming power figures taken from the crank TorqueCars suggest injectors of around 550cc for 390bhp, the 740cc injectors hit around 500 and 850cc will deliver fuel for over 600bhp). If you run lean you could destroy the engine so make sure you have some spare capacity in your injectors and fuel pump.

Don’t pay too much attention to induction kits and air intake unless you are hitting power figures over 300bhp, and even then please ensure you have a cold air feed and are not sucking in warm engine bay air.

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

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which parts work best for them on each model of car. Comments are used to improve the accuracy of these articles which are continually updated.

 

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