September 17, 2021

Alexandra Beer House

The Real Estate Experts

The Datsunworks KN20 Head Brings DOHC to the 240Z

The Datsun 240Z is one of the most beloved sports cars ever made. More than 50 years after its debut, people are still modifying, improving, and perfecting this legendary machine. Advancements in manufacturing have opened up a whole new world of possibilities for enthusiasts. Like Derek Minetti, founder of Datsunworks in Ocala, Florida. From scratch, Minetti has designed and built a kit to add dual overhead cams to the 240Z’s beloved L24 straight-six engine—using parts from another Japanese hero engine, Honda’s durable, highly tunable DOHC K20 four-cylinder.

Minetti is not a traditional engineer. At 18, he opened his own garage where he worked almost exclusively on Z cars and other Datsuns. He found the garage was more than he was willing to deal with, and eventually, he followed his passion for art into a career as a pattern maker, creating the forms used to produce high-end ornamental railing. Minetti’s decade-plus of experience with metal shaping and casting proved invaluable when his idea for a DOHC L24 started to come about.

“The whole thing started out first and foremost because I wanted one and it seemed interesting to me,” Minetti told Road & Track. “In the foundry business, nobody wants to mess with a cylinder head. It is kinda like the holy grail of castings.” But Minetti had a technique he thought could work, one that would simplify the prototyping stage and create a durable, high-performance part: 3D-printed sand casting.

Sand casting is an age-old technique: create a model, or pattern, of the part you want to produce, press it into sand to make a mold, then fill the mold with hot metal. The more intricate your part, the more challenging it is to make a perfect pattern, and every successive evolution to the design requires a whole new pattern. 3D-printed sand changes all that. A specially designed printer deposits sand into the exact mold shape you need. Casting a brand-new design (or updating a previous one) is as simple as printing a fresh sand mold. And when you’re working on something nobody has attempted before, like a new DOHC cylinder head for a half-century-old Datsun engine, that’s a huge amount of time and effort saved.

Datsunworks

Minetti had previously created an EFI intake for the Datsun L-series engine, which earned him tons of praise from Z-car fans. That project connected Minetti with many knowledgeable enthusiasts, most notably Tony Dighera, known as “Tony D” on the HybridZ forums.

Minetti and Dighera had spoken about their desire for a DOHC cylinder head in the past. When Minetti came up with his 3D-sand-printed idea, the two went looking for a head design Minetti could feasibly manufacture himself.

“Tony was instrumental in the suggestion to use Honda parts,” said Minetti. “I have to be able to visualize myself making it. I have limited tooling here, and I have to be able to build things in-house, otherwise I’m not interested… Depending on other people for timelines and other stuff sucks the fun right out of it.”

datsunworks kn20 head

Datsunworks

The Datsunworks DOHC cylinder head utilizes a ton of off-the-shelf Honda parts, including all the valve components, roller rockers from a K20A3, and a modified version of Honda’s own rocker shaft. The key to the whole project is the K20’s removable cam towers, which sold Minetti on the design. With pretty much every K20 cylinder head component readily available, the Honda design was an attractive starting point.

“Parts availability was really what made it a good choice,” said Minetti. “The K20 is backed by a strong aftermarket, strong support coming from everywhere. And there’s the familiarity standpoint—anyone who works on K20s can have this head sitting in front of them and they’re going to recognize it.”

Commonly available, tried-and-true components power this DOHC conversion. The timing system was designed with Nissan KA24DE parts to be compatible with the crankshaft snout on the old L-series. The Nissan bottom timing chain gets shortened and re-linked, but the KA24DE’s top chain, idler gear, and chain tensioner are utilized right out of the box. Minetti’s own car runs an off-the-shelf Cloyes timing kit with geometry as close to factory as allowed. The custom head even uses a standard L-series head gasket.

The mix of Honda and Datsun/Nissan parts inspired the name for this DOHC head swap: KN20, a K20 with some Nissan in the middle. “It makes people a lot more confident that there is going to be longevity on this,” said Minetti. “ Let’s face it, it’s a lot of money. When you spend that kind of money, you really don’t want to be hunting me down for a rocker arm and then hearing ‘I don’t have any on the shelf, we’re gonna make some next year.’”

datsunworks kn20 head

Datsunworks

The camshafts, however, are fully custom. In fact, getting the cams made was the most difficult part of this entire project. Minetti was assisted by Robbie Whitley from WhitelyTune in New Zealand, as well as Chase Knight of now-defunct Crane Cams. Another Crane employee suggested Minetti should make his cams out of through-hardened S7 tool steel, which can be custom-ground repeatedly without affecting the hardness of the lobes. Now, Schneider Racing Cams handles the cam fabrication, leaving room for customers to grind their cams to suit a particular application.

With the camshafts done, the KN20 head was officially a reality. Minetti’s old Z is currently running KN20 serial No. 001, and has covered about 10,000 miles since installation. No. 002 is reserved for Tony D., whenever he’s ready to install it. Customer kits really got started with No. 003, which was sold to a man in Florida. Not only was that the first official KN20 kit sold, but the buyer helped the project in other ways. Namely, that customer paid to have Dave Rebello of Rebello Racing port and finish the head.

In the world of the Z car, few names are as well respected as Rebello Racing. Upon inspecting the KN20 head, Dave Rebello was impressed. So were his patrons: The majority of KN20 sales have been to Rebello Racing customers. One of those customers was Rob Fuller of Z Car Garage, whose KN20-powered Z project made a splash with enthusiasts recently.

datsunworks kn20 head

Datsunworks

Fuller tells R&T that the cross-flow KN20’s exotic sounds, and its ability to reliably rev to 8500 rpm, made it attractive. “We are building complete cars that can handle the power,” Fuller told R&T via email. “You need a lot of tire, a transmission to handle the power, a rear differential with limited-slip, and of course excellent brakes.” The high-revving dual-cam engine, mixing classic Datsun character with a huge increase in capability, fit the bill perfectly. Z Car Garage is even performing track and reliability testing to learn more about how the KN20 can work in future customer builds.

Fuller is impressed by what Minetti created from scratch. “He is proof that anything can be accomplished,” Fuller told R&T. “We are huge fans of the Datsunworks cylinder head, and we hope to sell quite a few.”

Z Car Garage’s KN20 project is actually a longtime customer car known as Behemoth. The car is no stranger to hot-rod engines, having previously featured an RB30DET 3.0-liter turbo inline six (a popular Frankenstein engine made by combining two production Nissan powerplants) as well as a custom engine by OS Giken, the Japanese company that made the first L-series DOHC conversion. That said, the current engine, a Rebello-built 3.2-liter with a KN20 head, might just be the coolest of the bunch. Hardware upgrades include forged pistons, billet rods and bearings, Jenvey fuel injection with individual throttle bodies, and RacecraftNW equal-length headers. A six-speed manual gearbox borrowed from a 350Z sits behind the motor, while a 4.11 OS Giken LSD puts power to the ground.

z car garage kn20 build

Z Car Garage

Z Car Garage is still in the process of completing Behemoth, but with a conservative tune the car makes 350 hp and 248 lb-ft of torque at the wheels on 91 octane. That’s a lot of performance for an L-series, more than 100 hp per naturally aspirated liter. And that’s not even the peak: Minetti says the head can flow freely enough to make 500 hp without forced induction. Z Car Garage believes the platform is well suited for that path as well.

“A regular SOHC 3.0-liter L-series engine can make 300-plus hp in race configuration,” Fuller told R&T. “As you can see, with the KN20 head design and some breathing improvements… 100 hp more can be easily achieved. Just wait, we are only at the beginning.”

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As you might imagine, such performance potential has garnered a lot of interest. Minetti has serialized 16 heads thus far, skipping unlucky No. 13. Fuller confirmed that Z Car Garage has at least two customers lined up for KN20 builds. The interest isn’t solely about maximum horsepower: The KN20 head keeps the feeling and charm of the L-series motor, just with more free-breathing power. That’s something Minetti thinks you can’t achieve with popular V-8 swaps or turbocharging.

The KN20 does come with a price tag.The most common kit retails for $14,500—and customers supply their own valves, springs, seats, retainers, and rocker arms. Ferrea valve seals are required, and custom pistons are recommended for optimal performance. The camshaft lobes must be custom ground, and the cylinder head’s mating surface must be machined before installation. This isn’t a plug-and-play kit; rather, it’s a jumping-off point, ready to be tweaked to the unique needs of every individual builder and the dream for their dual-cam Datsun engine. A DOHC cylinder head is not a simple part. The fact that Minetti was able to design, engineer, and manufacture one in his own shop—one that makes great power—is impressive. The Datsunworks founder gives credit to the car community for helping inspire this project.

“The internet is the key,” said Minetti. “If you dig far enough, you’ll find the info that you need. The nice thing about going public when I did, not only did I have people cheering me on, but how many different sets of eyes did I get on this stuff? That was incredible.”

If you’re interested in purchasing a KN20 head for your own Datsun L-series project, check out Minetti’s website and cost estimator here.

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