It is a big project, and interesting. But a good power gain, and much less weight, is available by fitting a tuned V8, which is much less difficult.
There is a big thread on the forum about fitting a Cummins in a Defender, but it was a few years ago, and I can't remember who posted it.
In the meantime, here are some proper diesels in their natural habitat!
When I were a boy we had a few ERF all with gardners, this was their first attempt at trubocharging they did not fare so well, there were six in total with the gardner 6 pots, and as soon as one engine was fixed there was another waiting to take its place for repair.
We also had one with the naturally aspirated 8 cylinder, that never went wrong.
They all had one thing in comon though, oil leaks and lots of them!
When they came back home on a saturday morning the drivers all topped up their 25 litre tub of engine oil ready for the next week!
Turboman
Mab An Gov
Naturally aspirated Gardners in Scammell Explorer were a great engine.
I was never much of a fan of turbocharging anyway, it always seemed like a poor solution to a barely existent problem anyway. Those old engines were pretty frugal on fuel anyway.
The oil leaks seem to be a pretty constant feature of British engineering on all scales. I am not sure they were a bad thing either, the constant rolling oil change was probably one reason the engines lasted so long, and it kept the metalwork in the area rust free as well. That sort of oil is pretty cheap too.
I think the guy who drove the 8pot (called Bernard Savoury) used to switch off 3 cylinders when running light to save fuel.
I dont think the 6 pot models which were much newer had the levers on the injector pump?
Turboman
Mab An Gov
Can't remember, to be honest, but probably not.
The 4 cylinder Gardner in my boat had the levers, but they weren't about fuel saving, they were so you could switch off fuel to one cylinder, and use it as an air compressor, build up pressure in an air tank to use for the air start.
I think as the engines became more oriented to road vehicles, and electric start became better, the levers got phased out.
