I think the problem with a 1.9 IDI to TDI conversion is that the TDI piston will stick too far out of the top of the block. I don't have my piston book with me, but the distance between the pin and the top of the crown was different on the AAZ and 1Z pistons. That is why I am not pursuing that conversion. If I am wrong, let me know.What I am pursuing is a 1.6 to TDI conversion, because I found a piston that will fit the 1.6 block. This is on paper only... I have ordered the piston, but it has yet to come in. My plan is to then put a stock 1z head on the 1.6 block. I know there are some cooling hole issues that I haven't looked at. Setting the compression to about 18:1 (I forget the ideal number) will also probably have to be addressed. The 1.9 AAZ engine could be made into a 1.6TDI with cylinder sleeves. (assuming I am right about the 1z pistons being too tall).I don't want to mess with injector pumps, so I will probably lower the opening pressure of the TDI injectors to suit the older pumps. If that doesn't work, I will have to upgrade the high pressure side of the 1.6 pumps. I want to try to keep the price down.The intake and exhaust will be unchanged. I wish I could make better progress on this project, but getting the pistons has been really slow, and I don't expect them for another 2 months.
The machine shop called today saying the head is done. All the AAZ components will work in the head, cam, valves, springs, lifters. SWEET!!!!