Perkins Prima Engine Conversion.
I started making Prima conversions when I needed an alternative to the original petrol engine in my Land Rover. The first conversions used an aluminium casting to join the engine and gearbox and the flywheel and starter motor from a LDV van to complete the drive train. The mark II conversion uses Land Rover flywheel and starter, which are much easier to obtain, but I can still make MK I conversions.
Lot's of these conversions have been done and I think the majority of owners are happy with them, the characteristics are not that unlike the petrol engine, but at close to half the fuel consumption! The Prima engine's power output of around 80 BHP and 115 lbf ft-1 of torque, so it's marginally more powerful than a Land Rover 4 cylinder engine. The engine is free revving and it works with the standard Land Rover gearing. Series Land Rovers with their original engine's are far from economical to run[unless your other car is a Dodge Charger], the Prima is quite efficient even by today's standards and can return double the mpg that the series 4 cylinder petrol engine did; Someone did comment he was getting over 3x the miles, he replaced a pretty bad 4cyl petrol.
This Engine conversion doesn't require any modifications to the Land Rover bulkhead or chassis. The engine mounts bolt to the Prima block and to the Land Rover Chassis mounts. The Engine Adapter plate is designed to bolt to the Prima engine and the Land Rover bellhousing. People have told me they carried out the conversion in a day, but generally it takes a few days. Once the engine is bolted in place a few modifications are required to the original original Land Rover systems to connect them to the Prima engine. If you can replace an engine you can probably carry out an engine conversion.
The drive-ability and reliability with a converted vehicle should be excellent. I drive a Prima Powered Land Rover as an everyday car, the Montego engine has improved fuel consumption and performance considerably.