APEX TWIN

There’s a certain mystique to DOHC (or, for another era, OHV) head conversions. Just look at the names involved. Zora and Yura Arkus-Duntov and the near-mythical Ardun OHV heads for flathead V8s. Yamaha’s hot-rodded DOHC head that made the anonymous I6 in the Crown into the legendary MF10-spec 2000GT. And Osamu Okazaki’s OS Giken DOHC head for Nissan’s L-series sixes. Now Nissan itself, via NISMO, is building a short run of DOHC heads for that same L-series engine, making the SOHC motor into the dual-cam mill of Showa car owners’ dreams.

It is not, however, easy to install. Or complete. NISMO is very clear that anyone buying one (in Japan, possibly elsewhere) will need to work with an approved shop and source a lot of parts, some of them likely custom. And it’s frighteningly expensive. But more on that in a bit.

Why the continual fascination with the DOHC L-series when Nissan had a perfectly legendary dual-cam six, the S20? Well, there are still thousands of L-series motors kicking around everywhere, whereas I’ve never seen an S20 in real life and unless you’re a real Nissan otaku, you probably haven’t, either. It only made it into a few thousand Nissan products, the most notable of which is the S30 Z432 (which is, deservedly, a legend). So, the robust and well-known single-cam L-series had, in the minds of owners and racers, a missing cam. And many tried to engineer a solution.

NISMO’s solution is, as you’d imagine, very professional and tidy. It pulls liberally from the company’s OE parts bin, grabbing things like KA24DE valves, VR30DDTT lifters, RB26DETT valve spring retainers, that sort of thing. A lot of parts are custom-made for the application, and the total package of parts is extensive. Hence the price tag for the basic kit alone, which is missing a lot of the parts that will make it actually work.

That base price is $22,700 at today’s exchange rate. That’s before tax, and also before some highly recommended NISMO parts are considered. NISMO developed the kit for the L28 engine and tested it in the S30 Z-car only, so to make it clear the hood they had to tilt it 24 degrees in the engine bay. They’ll sell you a new oil pan baffle and engine mounts to do the job, but you’re on your own for working out how to get a transmission to mate up. The company has committed to making 300 sets; it may make more, but nothing’s official.

It also sounds incredible. NISMO bored out their Z-car prototype’s mill to 3.0 liters, and with the new heads it turned to 7,500 RPM and made a stout 300 hp and 217 lb-ft of torque. 

This is not a bolt-on, DIY sort of thing. It’s involved. It’s incomplete. And it’s undeniably cool. It very much fits within the recent tradition in Japan of high-buck restorations of what used to be, simply, old performance cars. But age, nostalgia, and the other subtleties of collectability have conspired to make many of them worth big-dollar restoration work. Unlike in the U.S., much of this is being provided by the manufacturers themselves, in a very limited fashion, making for some highly exclusive “remanufactured” cars.

That NISMO is applying that level of philosophy, development, and quality to a kit like this is proof that there are strong forces at work attempting to make longstanding enthusiast dreams a reality—for a price.