I will be getting my hands on an 81 diesel Rabbit Pickup soon, with a 1.6 n/a engine. I want to drive a diesel because I am a delivery driver, but I don't particularly like driving at a snails pace (I don't have huge expectations for speed though). I recently picked up 2 Polo 1.4 TDI engines (yes in the US) and I'm toying with the idea of using one (or both if at all possible) of those turbos.
So here are the questions:
What kind of boost can the stock 1.6 n/a block take (reliably)?
Can I use the original fuel pump, or would I need a TD one?
And does anybody know what boost the tiny turbo's from those Polo engines makes?
Sorry for the basic questions, I couldn't find exact numbers, and I've never played with diesel before.
There are quite a few folks over on the vwdiesel.net forum who have added turbos to NA engines. They will certainly take it provided you keep your EGTs low enough. An EGT gauge would be pretty much mandatory if turboing an NA engine in my opinion.
You can definitely use the original fuel pump. The "proper" TD pumps have a device called an LDA which limits fueling until the turbo is creating boost, reducing the amount of black smoke out the tail pipe. Once you've turned the pump up to use the extra air from the turbo, you will probably find you have a bit of smoke right off the line but it will go away once you have some boost. Alternatively you can ease on the accelerator slowly as the turbo spins up (that's what the LDA does) but that's not as much fun...
You CAN add an LDA to your pump, but it's not entirely necessary.
The little turbos off the Polos will probably work fine. You should be able to run your NA block with one of those turbos at about 10PSI all day long without issue. Just make sure the wastegate on the Polo turbo is working properly as it is likely going to be a decent restriction otherwise. With a small turbo like that you'll have boost come on very quickly too which will help with the smoke issue above. Be aware though you are most likely to have problems with head gaskets or bent rods if you start making tons of power at low RPMs - the 1.6 likes to spin!
Oh and I doubt using both turbos would give you anything useful other than a severe headache after you sorted out the plumbing. Compounds wouldn't work as they are both the same size.