The RB30ET (not RB30DET)-equipped Nissan Silhouette GTS. Photo Credit: Nissan via Michael Banovsky

Fans of the Nissan Skyline are familiar with the RB series of straight sixes, now legendarily powerful engines never sold here in the United States. But there was an RB engine that stands above them all, an incredibly rare one, all because Nissan never built it.

It’s called the RB30DET, but by tuners, not Nissan itself.

Of course, Nissan did make a number of other RB-series engines. The RB25DET and RB26DETT, for instance, are beloved Skyline engines. They are 2.5- and 2.6-liter engines, respectively, with Dual overhead cams, Electronic fuel injection, and Turbochargers, either one or two.

It’s a pretty straightforward naming scheme, and it helps tell a story.

The Nissan RB30E. Note the single overhead cam and fuel injection. Photo Credit: Nissan Australia via Flickr

Nissan also sold an RB30S, an RB30E and an RB30ET. You can tell that those are straight six engines with 3.0 liters of displacement, either carbureted (S), fuel-injected (E) or fuel injected and turbocharged (ET). You can see that there’s no DET here.

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Part of the reason for that is Nissan barely sold the RB30. Though Nissan designed and built the engine was almost exclusively sold in Australia was most notably used in Holdens, GM’s Australian subsidiary as a means of complying with stricter emissions standards, as CarPoint.com.au explains:

Under Australia’s 1986 unleaded fuel requirements, Holden’s engines from the 1963 EH series could only send the Commodore further backwards. Cash strapped, Holden searched the world for a suitable six-cylinder engine, even looking at Jaguar’s new sixes. Then word came through that Nissan was redeveloping its 2.8-litre six from the 280ZX into a special 3.0-litre engine for a unique Australian version of the Nissan Skyline, due also in 1986.

As Holden was already rebadging the local Nissan Pulsar as the Holden Astra and would soon supply panels and Camira engines for the next shared Nissan Pulsar, a Nissan-powered VL Commodore made sense.

Nissan’s 3.0-litre six was a jewel of an engine, engineered for a 400,000 km life and offering a third more power from 10 per cent less capacity while using 15 per cent less low octane unleaded, compared to Holden’s old 3.3-litre six on high octane leaded fuel.

The only Nissan that got the RB30 was R31-generation Skylines that were built in Australia and were popular in fleet sales at the time.

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This was not a performance engine. It was a low-power, big displacement grunty kind of motor. A base model put out a scant 150-odd horsepower when new, as Nissan advertised. Even the hot version, for a Australian home-market special GTS1 and GTS2 only made about 190 hp, as Michael Banovsky’s Modest Machines notes.

But with RB25 and RB26 variants putting out four-figure horsepower numbers when tuned, it became clear to the aftermarket that this stroked Australian special had a lot of potential. The trick was mating a performance head to the big alloy block.

Since the bore was the same between the RB30 and other smaller-displacement, more commonly-tuned RBs, the aftermarket started mating first modified RB20DE heads to RB30E blocks with the 1988 Tommy Kaira M30. In 1993, Nissan started making the RB25DET for the R32 Skyline, and then aftermarket tuners could put the more-easily mated twin-cam, turbo head on the bigger block—giving birth the to RB30DET.

I have a massive fascination with these engines. You usually see them in Australia and New Zealand’s drag racing and drift scenes, where the RB30 blocks are common.

Zak Pole runs one to near 800 horsepower in his R33 Skyline and I waste most of my idle time watching it shred its rear tires.

The sound is, for lack of a better word, strong. Listen to one on a dyno and it’s painful to hear, a kind of high-intensity drone. It’s not musical. It sounds like some kind of industrial equipment, or someone sawing through your neighbors’ whole house.

There are more musical engines. There are more beautiful engines. There are significantly more powerful engines. But the RB30DET is one of my favorites for the aftermarket building something that its original manufacturer never thought necessary.

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