pug 405 diesel - badgers
Hi folks, I am presently the owner of a 185,000 mile 405 non turbo diesel estate. I am a courier and it is the best motor I have ever worked out of. The question is, does anyone know how difficult it would be to drop in an early 90bhp hdi engine and box out of a 406? Any advice etc would be very gratefully received!
pug 405 diesel - xantia
The engine setup that you currently have is the same as a NA Citroen BX.
I know that the 1.9 TD XUD lump (as used in a multitude of vehicles including the Pug 406 and Citroen xantia) has been put into many a BX, so I reckon that you could easily graft in a 1.9 XUD. However, the HDI lump may not fit easily as it has more bits and pieces grafted on the outside, and are more of a pain to work on.
pug 405 diesel - Frogeye
Don't do the Hdi transplant!!! Very complicated electrics, fuel pump in tank etc. Stick with the reliable XUD engine. I had both turbo and non turbo 405 estates. Although the turbo was faster to accelerate, the non turbo was not far behind and great once would up, good for anticipation skills!! I also got over 800 miles from a tank!!
pug 405 diesel - Martin1981
Even fitting a 1.9 turbocharged lump into a normally aspirated diesel 405 would be quite an involved procedure, but by no means impossible, with the need for electrical alterations, changing the exhaust and radiator to name but a few. I would personally stick with what you currently have or look for a TD 405 or 406HDi.

Martin
pug 405 diesel - local yokel
I doubt the labour and mods would be worth the effort in terms of the value before/after of your car. As suggested, buy a 406 HDi, or get a 405/406 TD. My 405 goes all day (in France) at 80 mph, and I can't get it to do less than 40 mpg.

Really good, sub 100k 405TDs go for over £1k on Ebay.
pug 405 diesel - badgers
Cheers for the advice folks, y'all have a nice day!