Ok Ok Ok............No dout this is a silly question and yes I should know the answer but........................ "Can any sort of diesel engine be remapped or does it have to be a PD diesel and does it have to be a turbo diesel,.......... "

I think the simple answer is any engine can be tuned... to make it run more efficiently/with more power.

An engine can be remapped if it has an electronic controller, but if it isn't turbo'ed the gains are 'likely' to be lower (also depending on what kind of tolerances are available/left to play with).

If I'm wrong... feel free to shoot me down

Just about any engine with an ECU can be remapped but unless it's a turbocharged one the gains are likely to be very small and not worth the cost.

You'll only get about 5% on a normally aspirated engine compared to up to 30% on a turbocharged engine.

This applies to petrol or diesel