Having done some research, we have ruled out in-wheel motors as an option. The main reasons being that the unsprung weight would have an impact on the driver experience and the cost of two motors would be prohibitive. Assuming a standard motor mounted in-board, then a second-hand Tesla motor seems to be one of the best options but, our technology tracking to date (see the Facebook group posts) shows that there are many other options in development.
The only thing we are sure about right now, is that the OSSEV® will be rear-wheel drive only. The main reason for this is an undiluted feel through the steering wheel.
The Hyper 9 seems to be the default motor of choice in many DIY EV builds. It's easy to get hold of and well understood, with good support.
The Tesla SDU is used in a number of models and weighs 90kg. It spins up to 18,000rpm but has an in-built 9.34:1 reduction gearbox. With our planned 15" rims, this gives a top speed of 123mph. Voltage range is 200-420V dc and maximum current is 650A. Maximum power is 220kW (300bhp) and maximum torque is 330 Nm (243 lb-ft).
The Tesla SDU can fit either ahead of (mid-mounted) or behind (rear-mounted) the axle. If we opt for a mid-mount installation, then we have to swap phase and encoder wires and modify the oil pump to run in reverse. Both options mount require the inverter to be relocated.
The Emrax 268 is an interesting motor with a maximum rotational speed of 4500rpm. This is very convenient for our MX-5 conversion as it doesn't require a reduction gearbox, when driving the differential. With a 3.6:1 differential the top speed would be about 80mph. It weighs very little too (22kg) and can deliver 117kW continuously (159bhp) and 210kW peak (285bhp).
The Emrax 348 is another interesting motor with a maximum rotational speed of 4500rpm but, it is probably overkill for this project. It is also is very convenient for our MX-5 conversion as it doesn't require a reduction gearbox, when driving the differential. With a 3.6:1 differential the top speed would be about 80mph. It weighs about 44kg and can deliver 210kW continuously (285bhp) and 400kW peak (536bhp).
The Nissan Leaf motors are well engineered and readily available second-hand at good prices.
The later (2018 onwards) Nissan Leaf ZE1 motors can deliver 160kW/215bhp and 340Nm torque and spin to 11,300rpm. They feature an integrated inverter and a water cooling system that runs through both inverter and motor. The main issue with this motor/inverter combination is that it is quite tall. The inverter can easily be remotely mounted if required.
Zonic is a brand owned by Fellten / Zero-EV and they don't sell to individuals any more. They supply EV Europe and Legacy EV, who retail and support these products.
The Zonic 120 is a 12,000rpm motor with 280Nm / 120kW (161bhp) output. It operates at 250 to 450V and weighs 45kg + 6kg for the integrated controller.
The Zonic 180 is a 12,000rpm motor with 360Nm / 180kW (241bhp) output. It has a remote inverter making fitment in tight spaces easier.