How An Engineer Built A Hybrid Nissan Leaf With A Fire-Breathing Motorcycle Engine In Back

The “LeafZX” is what San Francisco-based engineer, Battlebots veteran, and lifelong car-nut Derek Young calls his creation, an electric Nissan Leaf aided by a 170 HP, high-revving motorcycle engine powering the rear wheels. The vehicular madness was a result of Young’s desire to meld his love for creating things and his interest in owning an electrified car that sounds and feels like a race car. Here’s a close look at the machine, and the impressive CAD models, and custom-machined parts that made its creation possible.

This past weekend The Autopian’s three founders, Jason Torchinsky, Beau Boeckmann, and I joined Matt Hardigree and Beau’s team at Pebble Beach’s absurdly extravagant “Car Week.” The Quail show was nuts, featuring every car exec and plenty of celebrities, and the Concours — the main event — was even nuts-er. But between those two celebrations of automobile beauty and opulence was a celebration of jankiness: The Concours d’Lemons.

The show featured some truly absurd and rare old junkers like a French MinicComtesse and a Lincoln Continental turned into a horse. But among all that sat an example of engineering brilliance so absurd that I’m not sure any human mind other than Derek Young’s is equipped to fully grasp it. Gather yourself, slow down your breathing, and hold onto something well-anchored, because this rear motorcycle-engined 2013 Nissan Leaf designed using Computer Aided Design (CAD) software and built in a half-car garage in San Francisco might just scramble your mind into mush with its sheer audacity:

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I took a few photos of the plug-in hybrid “LeafZX” during the event; from the front driver’s side, it actually looks fairly normal.

But from any other angle it becomes clear that “normal” isn’t remotely the right descriptor. Inside you can see that the rear seatback has been replaced with a firewall of sorts.

You’ll also see what appears to be an intake and some sort of duct:

These two reach forward from the seatback-replacing firewall to this scoop in the passenger’s side second-row window opening:

By this point, it should be obvious that there’s clearly some kind of party in the back, and indeed, there is:

It’s a motorcycle engine powering the rear wheels independently from the electric motor-driven front wheels. Just to the left of the gas engine sits the stock motorcycle’s fuel tank, and ahead of it on the right side of the car is a radiator, which draws air through the second-row window duct via an electric fan and exhausts that air through extractor holes in the rear hatch (see below). (The orange intake tube in the back seat area feeds the engine; you can barely see it just behind the valve cover and to the left of the radiator in the photos above).

In the passenger-compartment, you’ll notice some red buttons on the dash, an extra pedal in the footwell, and a sequential shifter built into the center console:

And underneath I could clearly see a custom subframe, a suspension from some car that is not a Nissan Leaf, and a custom-built chain-drive housing bolted to that subframe.

Baffled by what I was looking at, I had a chat with the vehicle’s creator, Derek Young. He described the fascinating way that he engineered and built this fascinating creation.

Who is Derek Young And What Led Him To Undertake Such Sorcery?

He’s A Car-Nut

To understand this build, you need to understand the builder, a man named Derek Young, who grew up near Toronto in close proximity to a car-loving dad. In his household was a VW Scirocco, an old Audi, a Datsun 240Z, and — when Derek was 13 — a Caterham Super 7, which his dad took rallying at Targa Newfoundland. Young was the navigator for the rally, and, as he told me over the phone, ended up becoming rather traumatized by the event. “The car was breaking every day, and you’re working on it every night,” he remembered, saying he couldn’t stop thinking of that stress for a long time after that race ended.

After Derek got his license, he received a racing helmet for Christmas and began participating in track days and autocross events. Then he left for Vancouver to study systems engineering in college, and snagged a Datsun 510 — a vehicle that he remembered having seen racing at Road Atlanta. With fiberglass flares and a cheap suspension, the car was a bit of a beater, though his friend did a nice paint job over the rather tired body. Young also snagged a $500 Datsun 510 wagon while at his university; this was the vehicle that got him headed down the path he’s now on. “For my thesis project I built a semi-automatic gearbox,” Young told me. “I basically built a pneumatic actuation system to push an H-pattern shifter through the five gears…That was my first Frankenstein project.” After a failed engine swap, he sold the car, and it remains someone’s unfinished project to this day.

Since his smaller engineering school didn’t offer a Formula SAE car design/racing program, Young satiated his need to build things via a different avenue. “I ended up selling [the crappy 510 with a new paintjob] to fund the start of my Battlebots career,” he told me, saying he won the robot combat show’s LA competition in 1999.

By 2003, Young was out of college and cruising around in another 510; this one was worth keeping. He fuel injected the L18 four-cylinder engine, which used the block from his dad’s rally car. He was working in the Vancouver film industry building Sci-fi props, but in 2007 he used his Battlebots connections to get work in the San Fransisco bay area. There, he turned his four-door Datsun 510 into a real rally machine (see below) that, unlike his dad’s Caterham, actually performed well at the Targa Newfoundland race that had traumatized him three years prior.

Over the phone, Young told me in a non-joking manner that he sold his rally 510 because it was impractical for his growing family. His replacement: A tiny Honda S2000 two-door convertible. Clearly he’s a bit of a nut.

He Always Wanted A Motorcycle-Powered Car

Battlebots and his growing family, plus a house purchase, left a void; Young needed to build stuff. “I want it to be something that I can park on the street and that I don’t have to restore. I want to build something,” he told me. Last year he jumped into the deep end.

“I’ve always wanted this bike engine-powered car,” he said. “Mostly it’s the sound. I was raised watching Formula 1 in the ’80s and ’90s… The crazy revs — that’s what’s most exciting for me. It’s the noise… it’s kind of a silly thing to build a car around, but there are no street cars that rev to 13,000. The sequential gearbox… is such a racecar thing… if you wanna do that with a streetcar, it’s not even approachable money-wise.”

His initial thought was to buy some small 1980s car like a Subaru Justy or a Mazda 323 GTX, or maybe an older Honda Civic hatchback or wagon, since he was part of a Honda CRX-based Lemons racing team. In fact, this is a bit of an aside, but check out how he turned a Civic into the Andy Warhol BMW M1 art car:

Young’s plan was to throw a motorcycle engine in the back and convert the front to electric (since the bike engine would need a bit of assistance, since bikes tend to lack reverse gears, and they lack low-end torque). But in early 2021, when Nissan Leafs were cheap, he realized that it was perfect for the job since it would cut out the hassle of converting something to an EV. Without taking any measurements, and using only underbody photos that someone on a Leaf forum had posted after installing a trailer hitch, he pulled the trigger on it and a 2009 Kawasaki ZX10R, a bike that was far from ideal, but that was powerful and available.

“I’d never driven one before,” he told me about the Kawasaki. In hindsight, he realizes that the bike was a bit compromised — its gearing is super tall to prevent wheelie-ing on a bike, though this just makes for lackadaisical acceleration in a car. “First gear will almost get you to 60 mph, and in 6th gear you’re running 8000 highway.” Still, the end product is worth it.  “It’s unlike anything else. It’s very much a racecar feel in a streetcar, and I don’t know how you could achieve it any other way without mega mega dollars,” he told me. We’ll talk more about the driving experience later in this article.

The Build Begins

“[The Leaf] is such a strange vehicle to do this in because the stock car is so docile and silent,” Young admitted.

The project began last June. The major components he bought in addition to the bike and car include an Ebay-sourced Lexus IS350 rear subframe — which he chose due to its track width and wheel bolt pattern, among other reasons — and a sealed Quaife ATD differential from Taylor-Race.com. Buying parts instead of fabricating them, and using a modern EV instead of an older EV conversion-candidate made the project possible for the family man. “I’m gonna try to do this in the most simple way possible where I’m on the couch designing things instead of grinding metal downstairs,” he told me.

To that end, he began importing his project into Solidworks, a Computer Aided Design software (CAD). “That was the real breakthrough,” he told me, saying the comments section of YouTuber and engineer Superfastmatt had inspired him to build a “Photogrammetry” rig to allow him to take photos of his parts so an open-source software could turn those photos into accurate geometry in the digital space. He used an old Olympus micro-4/3s camera with a polarizer setup to eliminate reflections. He then sprayed his parts with a cornstarch suspension in isopropyl alcohol; this gave the components visual “texture,” which allowed the software to better understand the geometry of the components. Here’s a look at the clean engine

:

And here’s a look at the engine after the cornstarch/alcohol treatment:

Here’s a peek at the engine in CAD, where it could be designed into the car first so that Young knew which parts needed to be made/modified to get the various mechanical systems to work together:

Here’s the clean rear subframe:

Here’s the treated rear subframe:

Notice the aforementioned visual “texture” that Young’s concoction gives the components:

Scanning these two components allowed Young to visualize their interface digitally:

“The rear subframe took three to four days [for] my CAD computer to figure out,” he told me before saying he also digitized the inside of the Leaf’s trunk and the underside of the floor. “[I] basically just pieced it together in CAD and started designing parts,” he said.

Here you can see how Young sprayed the rear cargo area interior and underside:

The result was a beautifully digitized packaging environment that allowed Young to understand which parts he had to design, which he had to buy, and which he had to modify.

While a judge for Battlebots, he’d watch a fight for three minutes, then sit for 20 — during the waiting period, he’d design his Leaf in CAD. By September, he started getting custom parts in the mail, including laser cut pieces he got from a company called “Sendcutsend,” who also does sheetmetal bending.

“It’s like an order of magnitude cheaper just because they have the process dialed so well,” he said, also mentioning another custom metal fab company named OSH Cut (see above). He told me he also used a laser tube cutting service for the shock towers — all of these custom bits, of course, were ones he’d designed in CAD.

“The subframe swap I did in a weekend,” Young told me, saying the car really never left the road for more than maybe a total of five days. He was working with a half-car garage, after all, since his wife had turned the single-car garage in San Francisco into a gym.

Having his parts custom-made, buying off-the-shelf bits, and reusing as much of the Leaf as he could were all key enablers in keeping the Leaf’s down-time to a minimum. On that last point, Young bought another Nissan Leaf twistbeam rear suspension, scanned it to get it into CAD (see purple above), and used that to create an attachment point that allowed him to easily bolt the Lexus’ subframe to the Nissan Leaf body. Here’s the subframe pre-modification:

And here it is after:

As for the rear of the subframe, Young cut the floor out of the Nissan leaf’s cargo area, and welded in some structure for the subframe to mount to:

A Look At Some More Hardware

The truth is that nobody other than Young can really do a writeup of this project justice, so I’m going to keep this all fairly high-level, pointing out the main components Young had to develop. You can see in the CAD images above that there’s some kind of transmission between that engine and the axle shafts powering the wheels down below that subframe. That transmission (or “drivetrain cradle” as Young calls it) houses a bunch of sprockets and a chain, which travels toward the front of the Leaf, then down, and then towards the rear, grabbing the sprocket in the rear differential, powering the axle shafts.

Here’s that drivetrain cradle made up of custom laser-cut parts:

Here is a packaging preview of how that cradle would sit relative to the engine when in-vehicle:

He even ran a Finite Element Analysis simulation to make sure the transmission could handle the engine loads:

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Here it is partly installed in the vehicle:

The axle shafts aren’t yet in, and really, they’re hard to see once everything is put together, though from underneath you can see them, but just barely:

Those axle shafts, by the way, are custom, using a Honda inner spline (the diff uses a Honda spline) and the stock Lexus IS350 outer hub spline. Young told me that making these custom axles was a massive pain in the ass.

There’s honestly so much more to talk about. Young sent me an album filled with at least 6.02*10^23 photos. I’m exhausted writing this article, because the album has so much gold in it that I want to mention it all. It’s glorious! But alas, that’s impractical. So here are just a few other cool images; check out Young’s shifter assembly design:

Behold his air intake duct, which he of course designed in CAD first:

Here’s a look at Young’s little electric actuator that taps into the Leaf’s pedal position sensor to pull the motorcycle’s throttle cable:

You’ll notice that it’s fed air by a big hose that hooks up to an air pump:

I was a little surprised that the throttle actuator needed its own cooling. Very interesting.

What’s It Like To Drive?

I haven’t had a chance to drive “LeafZX” quite yet, but per Young’s video showing the cabin during a highway onramp acceleration run, it looks like an utterly absurd good-time:

Here’s a clip of the car from the outside

Young’s had the car — which can be driven by either the electric motor or bike engine, or both — on the road for over six months, but has been tweaking it ever since. “I do take my kid to swimming lessons in it… he likes shifting,” Young told me. That’s just hilarious.

Young told me a bit about how the car drives, comparing it to the Chevy Bolt he’d owned and modified with a different sway bar and higher-performance tires.”I did one of my favorite routes…and [the Bolt is] lacking. It’s missing all of that excitement of my old 510 that I used to do all of these same roads in.”

“I didn’t know if [the LeafZX] was going to be good or not. I was very pleasantly surprised that it is fun to drive.”

“It’s fast. It’s a legitimately quick car. It doesn’t launch well… As you add throttle, because it’s an EV it wants to just drive away.” The motorcycle, though, hits peak torque way up high in its rev range, so the car tends to feel fastest between 30 MPH and 80 MPH. The vehicle’s zero to 60 mph time of 5.5 seconds, Young says, just doesn’t do it justice.

All images credited to Derek Young