Can I convert an engine without secondary air to have secondary air cost effectively

 

Cost effectively? No, not really. You'll need different heads, the secondary air fixtures that fit into the heads, vacuum pump, hoses, cannisters, the ECU, BCU, and instrument cluster from an SAI truck, and there would be some wiring to do.

Curious why you'd want to? Environmental reasons?

 

I live in Arizona and need to swap the engine because the old one is ruined and my current engine has SAI and all the engines I found on eBay seem to not have SAI so I was going to use one of their engines and just make it an SAI to pass emissions

 

In that case, you just need the replacement engine and a set of SAI heads. Prob an extra $300-$500 on ebay

 

You could just do a short block swap instead of the whole engine, if your current heads are in decent shape. The injection ports in the heads are the only place where the physical lump of the engine is different between SAI and non-SAI.

 

This, or you can just plug the SAI ports on the heads. J can't recall what the thread is, but you can figure that out once you've got the engine in front of you. I've deleted the SAI from both my discos and that's all I did. I actually took the existing plugs in the heads which are hollow for the SAI system and I welded them shut.

And honestly, the heads on your current engine are probably fine even if the bottom end is no good. You could also just swap your existing heads over.

 

SAI tubes have pipe threads, and you can buy plugs at most any hardware store.

 

Maybe a dumb question but how would the inspection service know that your particular Disco came with SAI when so many didn't?

 

Curious...why plug and weld? Would it not be easier to find some end caps for the SAI nipples going into the block?

 

There is nowhere to cap the sai tubes.