Offroad-Express

Hi guys I was wondering whether I can upgrade my non turbo 91 safari 4.2 to turbo and if so are many engine upgrades necessary to prevent engine damage?

I turbod my 88 gq about 3 yrs ago
Paid a guy to do it, as I had never really played with diesels. Now knowing how simple it really is to do I would suggest most mechanically minded people could eAsily do themselves. Especially if your after say 10 psi
All it is:
Fitting new exhaust manifold and turbo, oil pressure line in, oil out, silicon joiners and pipe from turbo to inlet manifold, and new air inlet to turbo, you could even use pod filter on turbo if not going in puddles, and new section of exhaust pipe off turbo to existing exhaust system, you can completely remove your mufflers , run straight pipe all the way. This is the basic setup

That's what I had in mind. Was there no internal work needed on the engine at all

no internal work required.
first thing is which engine you have. i can't recall exact details but i think black head engine is the weaker one, but still good for 15psi. plenty of info on the patrol forums about ID'ing engine and which is weak/strong.
there is limits with how much power you can get out of a stock pump without having to take it out and get it modded. again patrol forums have write ups on that.

don't forget you will need a cert for onroad use. adds to the cost and pays to get any tire/suspension upgrades done so it all get certed at the same time.