What’s So Special about SR20DET

If you’re a JDM fan you’ll probably agree that the 1990s was the golden age for Japanese performance engines. We got the 2JZ, the RB, the 4G63 as well as the Honda  K-series. All over-engineered, and all capable of producing power well above their factory spec. But there’s another engine that we haven’t covered yet and one that definitely belongs in that group – Nissan’s SR20.

The basics

The SR series engines were designed as a replacement for the aging CA series and came in a variety of models and capacities, but today we’ll focus on the SR20DET – which is the performance model of the group and the successor of the CA18DET. So what exactly is the SR20DET? Well, like all Nissan engines, it’s right there in the name. SR is the engine series. 20 refers to the engine size or capacity of 2.0 liters, D stands for Dual overhead camshaft,  E stands for Electronic Fuel Injection, and everyone’s favorite, the T, stands for Turbo. 

Initially, the SR20 appeared in the engine bays of Bluebirds and Pulsars, including the famous Pulsar GTI-R and it wasn’t until 1991 that the SR20 finally arrived in the longitudinal placement we all know and love, in the Nissan S13. The SR20 turbo stayed with Nissan’s S-chassis until the end of its production in 2002. Despite being in production for over 13 years in practically every configuration imaginable and powering 18 different Nissan/Infiniti platforms, the only variants that made it to America were the naturally aspired SR20DE found in Sentras, Pulsars and Infiniti G20s.

Most JDM enthusiasts will tell you that the SR20DET is a longitudinally mounted engine (that is, north south oriented). However, the turbo engine was actually first introduced in a transverse engine configuration in the engine bay of the Nissan Bluebird 2000SSS.

Horses for courses

Horsepower junkies will often argue against the SR20DET engine, since it’s not based on an iron block or that its output can’t compete with that of the inline six-cylinder RB or JZ engines. However, there are compelling reasons to go down the SR route, depending on your application. 

The SR’s aluminum block in a Front-engine, Rear-drive setup, helps to maintain the excellent weight balance that the S-Chassis is known for. That, in turn, contributes to the car’s neutral handling. The RB and JZ engines weigh considerably more, which puts more ballast toward the front, which is fine for a drag car, but if you want to go round corners in a drift, rally or circuit-style car – that’s less than ideal.

Which one to get?

Early S13 SR20s were commonly identified by their valve cover. The “Red Top” and “Black Top” (these were sometimes referred to as “Flat Top” as well) engines came with a “High Port” cylinder head with non-variable timing camshafts. The engine made use of 370cc fuel injectors and a Garrett T25G taking care of forced induction. All this translated to 205hp and 203lb-ft of torque, pretty healthy numbers for a compact sports coupe.

S14 Silvias came with Nissan’s newly updated SR20DET with Variable Timing Control (VTC). This engine, characterized by its unusually shaped valve cover, earned it the nicknames “Notch Top” and “Slant Top.” The new cylinder head, known as the “Low Port,” features a redesigned intake manifold feeding slightly smaller ports for increased intake velocity. This engine received a larger, Garrett T28 turbocharger which, combined with the VTC and new cylinder head design offered improved response while delivering greater peak power of around 220hp.

In 1999, Nissan unveiled the final S-chassis to be powered by an SR20DET engine, the S15 Silvia. The SR20DET that powered the S15 Spec R continued to benefit from the VTC cylinder head and came equipped with a Garrett GT28R ball-bearing turbocharger and bigger, 480cc injectors. 

For this engine, Nissan eliminated the “dumb” coils with the external igniter in favor of “smart” coils with built-in igniters. An improved engine management system regulates the fuel delivery and ignition timing to produce 247hp. 

So which one of these is best? While they’re all fairly solid options and all can make decent power, our pick would be the version found in the S15 Silvia, or, if you can find one – the version with the Neo VVL head with variable timing and lift control (though this one never came stock in the Silvia platform).

Things to watch out for

Just like any second-hand engine, there are things that you’ll need to look out for when buying. This is especially relevant with engines that came from Japanese performance cars and have more than likely had a pretty hard life.

SRs can suffer from oiling issues. The oil pan is relatively small and the oil pickup is located only a few millimetres from the bottom of the pan. So, if the pan takes a hit from a rock, speedbump, or particularly aggressive bottom out while flying down the touge, it can in turn hit the pickup which will crack at the top and lose suction. At that point the engine won’t be getting the oil it needs to survive.

With that in mind, it’s the high-wear areas that you’ll want to pay attention to, due to the age of these engines now. Hard driving conditions and age are certainly wearing rings and cylinder bores, while low oil pressure can lead to spun bearings.  And, as many SR owners told us, these engines frequently throw rocker arms, as a side effect of valve float.

Like any engine that is starting to get a bit long in the tooth, it also wouldn’t hurt to take a look at the injectors and ignition system fitted if you are planning on using any of the original stuff.

Swapping your standard cylinder head for the VVL Neo or VE type is one of the most popular and most effective mods for the SR20. This head can be found in the JDM spec Primeras, Bluebirds, and the Nissan X-Trail. The VVL head offers improved airflow, higher compression, and improved coolant passages, and in our opinion is the best base to start with in a performance SR20 package.

Popular Mods and Tuning

The bolt-on friendly SR20DET welcomes most modifications and will reward you with increased power and if done correctly, reliability. Once you’ve made the usual intake, downpipe, and exhaust upgrades, investing in an aftermarket engine management solution is going to be your next step – because you’re going to need it to get the best performance out of further modifications like intake manifolds front-mount intercoolers, upgraded injectors, fuel pumps, ignition systems, exhaust manifolds, and of course the ever popular – upgraded turbocharger and big boost! 

Haltech offers Plug’n’Play solutions for all S-chassis applications from S13 to S15. The affordable Platinum Series Plug-in ECUs connect directly to the factory harness, while the Elite ECUs connect via an adaptor box and harness. In both cases the installation is really simple and once plugged in, all you need to do to get the engine running is load the base map. You’re now ready to tune. 

SRs are well known for throwing rocker arms, so if you’re taking the valve cover off to upgrade the camshafts, it’s a good idea to add rocker arm stoppers to keep them in place. If you’re hardcore, ditch the hydraulic valve lifters in favor of solid lifters. Since solid lifters can’t “pump up”, they reduce the chances of the rocker arms being flung from their positions. The only caveat here is that solid lifters are quite fiddly when it comes to dialing in the valve lash. Even so, many argue that the effort is worthwhile since they probably won’t need to be adjusted for quite some time. 

When you’re ready to step up to the next level, it’s time for engine internals. The alloy cylinder liners of the SR20 can only be over-bored 0.5mm or 20,000ths of an inch twice (86.5mm and 87mm) before the liner walls are too thin and you are forced to re-sleeve the block. 

Fortunately, there are a few choices available when it comes to re-sleeving a block, and aftermarket ductile iron cylinder sleeves mean you’re open to using much larger pistons. It’s also a good idea to upgrade connecting rods at this point, considering the engine is already stripped down. There is no shortage of aftermarket internal engine parts for the SR20, including stroker kits or even billet cranks.

As always, improving the airflow in and out of the cylinders is going to improve performance. You can install higher lift and longer duration camshafts, along with larger valves and port work. But remember, bigger isn’t always better. Head porting, valvetrain, and camshaft selection go together with turbo sizing to achieve the desired peak output and torque curve. 

Going big with high peak power output is great if you’re drag racing, but usually means the down-low torque will suffer – so make sure you are getting the right cylinder headwork for the kind of work the engines going to be doing.

If you’re thinking about taking your SR20 apart and upgrading the internals we highly recommend doing an interactive engine building course with High Performance Academy. They actually have one specifically for the SR20. See links at the end of this article.

But wait, there’s more…

If you’re a big fan of the SR20 but you’re not too keen on rebuilding an old engine, we might have some really good news for you. Rumour has it that after over two years of negotiations, Nissan sold the tooling and the design files for the SR20 to a Japanese firm called Mercury Enterprises. The company plans to build crate engines and make them available to the public. Now for the bad news; the initial quantities will be very small – we’re talking a maximum of four per month so the wait for your brand-new SR20 might be a few years!

Resources

Haltech’s Range of S-chassis and SR20DET compatible ECUs
High Performance Academy SR20DET Engine Building Course
Wiseco SR20DET Performance Pistons and Rods
K1 Technologies SR20DET Billet Crankshafts