What is this thing?

A complete 2013 Nissan Leaf augmented with a 2009 Kawasaki ZX10R motorcycle engine running the rear wheels.  The result is a an AWD road-coupled plug-in hybrid. 

Why?

I have wanted a motorcycle engine powered car for the revs, the sound, and the sequential gearbox. I did not want to use a tiny vintage vehicle as a starting point, so I looked into more modern vehicles and using a front wheel drive EV seemed like a great way to do it.  The electric powertrain gives you a reverse gear out of the box and all the power and torque needed to get the car going without slipping the clutch to the moon. The completed car has exceeded expectations and is fun and engaging to drive.   

Why a Leaf?

 The Leaf was chosen due to its low cost, availability, and abundance of free space in the back end for the engine install.     The Chevy Bolt also considered, but is too expensive (at this point).

The 2013 Leaf has some advantages over the 2011-2012, improved steering and suspension tuning and no charger behind the back seats to impede installing an engine.  The base car here however did not benefit from the late 2013 introduction of the more resilient "Lizard Battery", and suffered from poor State of Health (60%) with only 38k miles.  

Starting with a clean car where everything works (it has a heated steering wheel!) was also amazing, especially when my previous projects have been vintage (Datsun 510s) or scrappy 80s-90s Honda race car builds. 

Why not a 'Busa motor?

 Liter bike motors are substantially cheaper.  Anecdotally 1L bike motors don't seem to suffer from oiling issues of large bore mills that necessitate dry sumps or at the very least aftermarket or modified pans.  With the EV front drive, low end torque is also not as big a deal as with an ICE only Bike Engined Car.

What were some of the design principles?

Efforts were made to keep this complex project as simple and quick to build as possible.  These concepts helped guide the project, and helped make it possible to complete:

• Use as much of the bike as possible with as little modification as possible.  Retained all electrics, fuel tank, stock oil pan and exhaust.

• Design custom parts so that existing parts don't need to be heavily modified.  The shifter was designed to work around the existing center console, rather than other way around

• Leverage existing mounting points on the car. The twist beam mounting points become front subframe mounts, rear seat back mounting locations become firewall mounts, etc.

• Keep electrical intrusion to a minimum. The only connection to the Leaf is an intercept of the dual throttle signals and 12v to supply the bike engine electrics.

• Design as much in advance before fabrication to allow for CNC processes to be used to make parts that fix as expected.  Spend time comfortably designing on the couch instead of grinding metal. Due to careful planning and design, the largest fabrication project, the rear subframe and suspension installation, took only a weekend.

• Keep the car running.  Do everything possible to keep the car in a state where it can move under its own power.  Total down time like this during this project was around 5 days.

• Try to find the simple solutions. It was cheaper and easier to point a reverse camera at the bike gauge cluster in the engine back and display the feed on a screen than run cabling and mount the bike gauge on the dashboard.

• Pay for parts and services when they can advance the project quicker.  Many people doing chain driven cars build their own sealed differential, I  chose to purchase an expensive sealed Quaife ATB to skip this part.   Custom half shafts were manufactured by a specialist shop instead of cutting and welding the original half shafts.

How long did this take?

June 2021-September 2021: Planning, major non-custom component procurement, 3D scanning, and designing in CAD.

October 2021-December 2021: Custom parts landing, majority of fabrication.

December 2021-March 2022: First drive and first failure, on road sorting, and final major fabrication tasks.

March 2022-onward: Reliably on road, making continual improvements. 

What technologies and vendors made this possible?

3D scanning via photogrammetry (Meshroom, Metashape, Meshlab), CAD (SOLIDWORKS) instant quote online fast-turn laser cutters and machine shops (Sendcutsend, Oshcut, Fictiv), laser tube cutting (Precision Tube Laser), FDM abs and HP MJF 3D printing (Xometry and CloudCraft), Arduino, Clecos, eBay, McMaster-Carr, Amazon (of course). 

What's the rear end from?

The rear subframe is from a 2008 Lexus IS350.  Chosen due to similar track width to the Leaf, same wheel bolt pattern, standard coilovers (only need to add in one new loading point), and a small footprint to not interfere with the HV battery. Custom shock towers were installed, rear subframe mounts were fabricated.  Front mounts utilize stock Leaf twist beam mount points by grafting sections of a Leaf beam to the IS subframe.

How does the engine connect to the wheels?

Via a 530 chain drive, starting with a 15T drive sprocket, over an idler sprocket to a sealed Quaife chain drive differential (Honda Civic ATB core) with a 55T main sprocket attached to a custom "Cush-Drive" utilizing Ducati parts, and then back past an adjustable tensioner to the engine.  Inner Honda tripods connect to Lexus outer CV joints via custom half shafts from Dutchman Motorsports.

Can you adjust the power level of ICE and EV? Can the car charge sustain?

An analog bias knob adjusts the proportion of the Leaf throttle that gets sent to the drive-by-wire servo on the bike engine.  From 0 to 500%.

Additional adjustment is via Leaf settings. "B" adds higher regen, "ECO" disabled EV power for first 1/4 of pedal travel.  In this mode, the EV will regenerate during this portion of throttle position while the ICE pushes the car forward effectively charge sustaining.

How does the engine know what to do?

A Ruggeduino reads the throttle signal from the Leaf's pedal and sends signals over RS-485 to a Dynamixel robotic servo attached to the throttle bodies of the engine.

Does the Leaf ECU know what is happening?

No, when the engine is supplying power the Leaf ECU thinks the car is driving down a hill. 

How do you shift gears?

A custom 4-bar linkage coming out of the center console change tray actuates a push pull cable that actuates the sequential bike gearbox.  Upshift via pulling rearward, downshift via pushing forward. The shift knob also features a micro switch that cuts ignition on upshift for no-lift quick shifting.

Is there a clutch?

Yes, the standard Kawasaki cable driven clutch is controlled with a custom built clutch pedal assembly mounted in the traditional location.  The Ardunio monitors the clutch and at low speed keeps the engine at idle when depressed.  Driving off the line is done via EV power only and the clutch is dumped once the car is rolling.  This creates an LMDh like experience at every stop sign.

What's the range? What's the gas mileage?

EV only range is ~25 miles thanks to the <50% battery state of health leaving 12kWh effective battery capacity.  In stock form (LRR tires, less weight, more efficient aero) range was ~35 miles.  With a full 5 gallon tank, the car can go ~100 miles of spirited driving between fill ups while charge sustaining.  

How much did this cost?

Including the bike ($2200) and car ($5000) the total right now is around $25k, which includes paying for services such as structural welding. 

How quick is it?

GNSS performance meter recorded 5.5s 0-60mph. EV only ~9s 0-60.  The car turned a 1:31 lap at Streets of Willows (Extended, CW) in February 2023

How much power does it make?

Leaf EV powertrain is battery limited to ~145hp (with upgraded 160kW Leaf Plus inverter), and the Kawasaki engine is rated to 174hp = approx 320hp 

How fast can it go?

Top speed is limited by the EV system, which stops providing torque at 90mph.  The ICE can push the car to 100mph, but the EV system doesn't allow anything past this.  There are ideas to work around this, but this is only useful on the track, and as such hasn't been developed

Is it loud?

Louder inside than outside, as you are essentially riding inside a car with a motorcycle. Even with a sealed firewall and sound insulation hearing protection is used. 

How much does it weigh?

~3800lb, 51.5%f / 48.5%r distribution

Wheels, tires and suspension?

• 18x9.5 +38 Enki TS-5

• 265/35r18  Falken Azenis RT-615k+

• Custom BC Racing DS series coilovers 

  • Juke front application 5kg/mm (1.7hz)

  • IS350 rear application, 13kg/mm (1.9hz)

What is the fuel system?

Stock ZX10R fuel tank and pump with welded tank entry for filling through an areo style filler.  All vapor recovery systems are retained.

What is the exhaust system?

Stock ZX10R header with catalytic converters to a 2.25" Magnaflow resonator and muffler exiting though a turn down under the rear of the car.

What is the cooling system?

A scoop in the passenger rear window is ducted to a Honda Civic radiator mounted in the firewall, which exhaust into the engine bay (trunk), this exits the car through ventilates panels in the hatch. 

Do you not like BEVs or something?

No, I love EVs.  I daily drive a Fiat 500e and think that most people should be driving EVs.  At the same time when driving for pleasure or sport I enjoy the sounds of a high-revving engine and the mechanical interaction of manual shifting.  This car was built to satisfy this desire while using EV technology.