Replacing a 2.5L Diesel Engine with an Electric Motor (Land Rover)

We’ve just taken on another car, a 1984 Land Rover 90. So very similar to the 1985 Landover 90 that we’ve converted before. Now this will get exactly the same treatment as our previous conversions in that it’s getting a Netgain Hyper9 motor, which will be connected to five Tesla model S batteries to create an electric Land Rover Defender.

We only got this car a couple of days ago and we’ve taken the engine out, so this is a perfect opportunity to show the difference between the engine that comes out and the motor that goes in.

land rover defender electric car conversion
The diesel engine that was removed from the Land Rover

Diesel Engine and Electric Motor: The Main Differences

In the car is a 2.5 NA engine from 1984, it’s a military spec engine and the original engine that was in the car. It’s very, very, dirty and oily. Let’s go through a couple of the main differences between it, and the new electric motor being installed:


The first thing is obviously size. The massive diesel engine and all its ancillaries took up the entire engine bay, the electric motor is much smaller and will sit just in front of the original gearbox, which keeps it very low, leaving all the area above for other components. The batteries will sit in this space, as will the DCDC, management systems, the inverter for the motor and the charging system.


Beyond size, there’s obviously weight. We don’t know the exact weight of this engine, but it is somewhere between 250 or 300 kilos. The Netgain Hyper9 motor is just 50 kilos, so significantly lighter. Now people are always thinking that batteries are super heavy, so make up for this reduction, but we actually take weight out of our conversions.

Let’s consider the original engine plus its ancillaries 300kg, in our conversion we’ve got the motor at 50 kilos, battery pack at 125 kilos, plus a couple of bits and bobs and we’re only pushing 200kg all in. So ultimately the car is getting a lot lighter, which is not only great for efficiency but better for steering too.


Now let’s talk about performance. From new, the original engine had 68 horsepower, it definitely doesn’t anymore because on its way here from Somerset the car didn’t go over 45-50 miles an hour. The engine will have lost a lot of its horsepower over the years and getting a two-and-a-half tonne car going up to modern speeds is almost impossible. The Netgain Hyper9 has got 120 horsepower, so double the original and also double the torque.

This opens a whole world of opportunities in terms of driving, it makes it much easier to drive as the added torque means you don’t ever have to change gear, we just stick it in third and off we go. The torque curve is so wide that it allows you just to accelerate from the lights and third gear as if it was an automatic car. If you tried to accelerate from the lights in third gear with the original engine you would just continuously stall, or ruin your clutch, so it’s a huge upgrade, even though it’s so much smaller and a fifth of the weight.

hyper9 electric motor for land rover conversion
The Netgain Hyper9 Electric Motor in the Land Rover


The electric motor in this conversion is air-cooled, but we do actually run a little bit of water cooling for the inverter. The inverter for the motor has coolant going through it to cool it down a little, but the temperatures are nothing like the temperatures produced by the original engine. We’re trying to keep the inverter at 30 degrees rather than 50, rather than cooling 80-90 degrees in a combustion engine.

Moving Parts

A combustion engine has hundreds of moving parts, pistons, shafts, belts, bearings, an alternator, starter motor etc. A lot to go wrong and a lot to service. That’s ultimately why this has been pulled out, we’re fed up with 40 years of problems. In an electric motor there’s one moving part and that’s the output shaft, it spins and that’s literally it. Other than that, it’s like a computer, you don’t service your computer, you don’t change the cambelt on your computer.


The original flywheel housing is mounted upon the electric motor with an adapter plate, this allows the original clutch and flywheel to also be mounted to the motor. We’ve been able to create this system in order to connect the electric motor straight to the original gearbox of the car. We use the original gearbox as a way to keep the costs down, electric conversions shouldn’t be expensive, they should be attainable for people wanting to get into electric vehicles.

This allows us to base our pricing off a new electric car like a Renault Zoe or a Nissan Leaf. The only way we can do this is by using the original drivetrain, as soon as you start refabricating drive systems, drive shafts, differentials etc, the cost goes up significantly because obviously it’s a lot of our time and it’s a lot of custom fabrication.

Everything behind the gearbox stays exactly as it is, therefore, the four-wheel drive systems and the high and low gear ratios are maintained. You can even change gear, which is a bit weird and an electric car, but it works really well. If you want quick acceleration, use second gear, if you’re on the motorway, use fourth and if you’re off-road, use first.

We always start our conversions with the motor because everything else goes above it. Once it’s in, it will be held in position through our fabrication of a motor mount, which will sit on the original engine mounting points. We’re not securing the weight of the motor as much as we’re securing the rotational force. 120 horsepower just trying to twist itself, really has to be clamped down really really tight to hold it exactly in place.

electric car conversion, electric land rover defender

Stay tuned for further information on this electric Land Rover, and other electric car conversions. To view the original source, visit us on Instagram.

Reviewed by Barnaby Birkbeck (Founder) & Toby Wilson (Head Electrical Engineer), in 2024.

This article has been reviewed by our team of professional experts for accuracy and relevance. However, the information provided is for general informational purposes only. We recommend consulting with us for personalised guidance.