The Corsa B diesel engines came in the following variants
The isuzu engine codes are on the front of the engine:
5D = 4EC1
17D = 4EE1
On some engines only the last two digits are cast (C1 or E1), the T is displayed under cylinder 2, the rest of the code under cylinder 3+4.
Corsa B's didn't come with the 1.7TD isuzu lump they were found in astras, cavaliers and vectras.
Now the the 1.5's are thought to be the best engines as they are renound for reliability and giving maximum mileage. All corsa B diesels had Isuzu lumps in.
For the running on SVO (Straight Vegetable Oil) again the Isuzu TD blocks are best as they have the all inportant Bosch (Nippon Denso) heated fuel filters. Apparently you can use %100 in the warmer months and just add abit of unleaded in the winter and its quite happy and no heat exchanger is required
Any Corsa fitted with the Lucas or CAV fuel pump shouldn't be run on SVO as they die very quickly as their self lubricating. The heat exchanger (FPHE) to heat the oil is thought to be much more efficient than glow plug method.
After much reading for perfomance gains the 1.5 TD engine is the best to go with and can be done at minimal cost. PooTube is littered with videos on Corsa's with this engine giving some impressive ouput.
Corsa 1.5 TD Isuzu EngineX15TD Corsa 1.5 TD Engine
EC1 Corsa 1.5D Engine
X17D Corsa 1.7 D Engine