When the guys from Shifted Interests found a cheap Smart Fortwo with a broken diesel engine they knew exactly what to do. After removing the factory powertrain, they made custom motor mounts to hold a 998 cc inline-four from a 2002 Yamaha FZS1000 Fazer motorcycle to the rear subframe. The engine’s 149 horsepower and 78 lb-ft of torque is sent through a custom jackshaft to a welded Smart Fortwo differential supported by two heavy-duty bearings. The team machined the differential to use a motorcycle sprocket so it can be driven by a chain. They covered the new powertrain with a custom firewall made from 1×1 inch tubing covered in sheet metal. All the work from beginning to end is covered in the video build series. The team enjoyed the project so much they plan on building another with a Suzuki GSX-R750 engine.
Source: @shiftedinterests and Shifted Interests