Hello everyone. Hope you are all doing well.
I have a Nissan Sunny B13 in white and for the last 21 years that I had it, It had the CD17 engine. The engine had been through 3 overhauls and the generator was failing constantly now. So rather than going for a 4th overhaul, I decided to change the engine.
I went to Ahaata Mithu Khan in Saddar Rawalpindi as I saw on this forum and other mechanics in Islamabad and Rawalpindi had told me that they could help. Fair enough, I found alot of Nissan CD engines, but the one that caught my eye was a CD20T (2.0d Turbo). I knew the cd17 engine produced 54bhp and 104Nm at 2800rpm, but the CD20T produced near 90bhp and 174Nm at 2400rpm ! And since the price for the CD20 and CD20T were the same, you know which one I'd choose. 
But there was a little catch. Mr Ashgar Khan said that he won't sell it with the electronic injection pump that it came with, because to whomever he sold the CD20 with that injection pump, the customer came back to him with alot of complains that it's won't start, accelerate etc etc. Bascially he said he doesn't know how to wire the ECU. 
So I agreed to fit the mechanical injection pump in my cd17 to the CD20T (yes, they are compatible). So all was done. Engine+transmission was changed and money exchanged hands (50K for those of you who were wondering).
The car is now joy to ride! Lots of low-end-torque! Put it in 4th gear while coasting in 45km/h and put your foot down. It pulls hard once the turbo kicks in.
But there were several issues (at the start):
1. You can?t plant your foot down for too long. Otherwise the engine overheats.
2. Secondly, The economy is 12.7Km/l (max). I have searched the net and asked other cd20 owners. They get a good 15km/l and 16.5 on the highway. I suspect that?s the result of fitting the mechanical pump.
3. On the highway, the engine WILL overheat if driven continuously at 125km/h.
4. Lastly, The gear ratios seem wrong. The forum member "Spectra" with his thread
https://www.pakwheels.com/forums/engine-transmission-powertrain/27745-cd17-cd20-nissan-sunny-b13
Says the following:
1st gear change at 45
2nd at 90
3rd at 120
4th at 155
and so on and so forth
My car is screaming at 90km/h in 3rd gear! I'm sure it's operating near red-line. And, on the highway, it maxed out at 160km/h.
Over time, I have learned what and how the various things work in the engine. For example, I saw that many of the wiring/plugs were left unattended. One water inlet was not attached and the EGR valve was not functioning. Also some air inlet/outlet pipes were also not connected. Spot the difference in the pictures.
I suspect that the wirings/plug were for the electronic injection pump and unless I don't have any expert on wiring ECUs, it's a dead end for me. Maybe the plug and the cut wires in the mechanical pump are connected?
The water inlet, on the other hand turned out to be the water inlet for the turbo! I used my engineering skills to craft out a T junction in the top radiator pipe and fitted the extra end to that inlet. Thank God the engine runs cooler now even under hard acceleration and continued use. Haven't tested it on motorway though. It did slightly overheat once or twice during peak summers, but I got that frontier sorted.
Looking at some other CD20T engine pictures I figured out that the unattended air inlet/outlet at the top of the engine head (the air-oil separator), goes to the turbo inlet pipe. When I did connect a pipe (from some other car) on to the radiator pipe, the engine ran smoother! And also, when I revved the engine, the temperature gauge would plummet. So that's good I think.
Next was the EGR value. I learned about their working and their advantages and disadvantages. Personally, I think the disadvantages far out-weigh the advantages. I don't want carbon to accumulate in the injectors and intake manifold. The EGR value should only open when the engine is cruising under light/medium load (to lower combustion chamber temperatures and prevent engine over-heating). And since the EGR value was operated by the electronic pump, I figured I should have a manual switch so that I can have the control in my hand. I fitted switches with LEDs in the cabin to turn on the EGR using a vacuum solenoid. In city, the valve is off and when I coast at say 100 or 125 on the highway, then I turn it on. (Haven't gone on highway after this modification though). We'll see what happens.
My immediate future plan is fit an intercooler to the engine. 
With an intercooler, The intake air temperature will be lower and hence the engine will run even cooler. Also, since the air is cooler, it will be more dense and hence I'll get more power out of the engine. But it?s torque I am looking for. The CD20Ti (Turbo and intercooler) has more than 200Nm of torque. It will be even more fun then!
So, that's all I have done uptill now. If someone can help me out to make the performance and mileage better, I will be very grateful. 
