1.8D vs 1.8TD

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1.8D vs 1.8TD

Post by nametooshort »

Am I right in assuming that like a lot of diesel engine families from the 80s, there is significant differences in the engine between the XUD n/a and turbo units?

Like, VW enignes for example have major difference like under-piston oil sprayers and various other things, so you cannot just swap the inlet/exhaust systems and fuel pump over to make a turbo engine from a N/a one, you have to start off with a whole turbo engine to begin with.

Is this also the case with the XUD family?

Or do they share the same block/bottom end, and therefore its only a matter of bolt-ons? (but I doubt this very much).

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Re: 1.8D vs 1.8TD

Post by Peter.N. »

The turbo's usually have stronger con rods and as you say oil cooling, I believe the heads are the same although they may have a thicker gasket to lower the compression a little but don't know about the crankshaft. If you only want an occaisional boost in power you would probably get away with turbo'ing a standard engine but for continious power you would be pushing your luck. If you fit one and dont use the extra power it should improve your fuel consumption.

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Re: 1.8D vs 1.8TD

Post by nametooshort »

Oh, OK. I know the VW 1.9d engines for example, turboing a n/a engine is pretty much complete suicide, because the pistons melt since they don't have cooling jets of oil.

But then again, the VW 1.9D family of engines is not exactly great. They are successors of the old 1.6d engine which in itself is not a 'real' diesel, but a Golf ohc gasser converted to diesel. You cans see its gasser heritage everywhere, even the vacuum pump which is stuck in place of the distributor, and looks like a distributor. That family of engines is somewhat weak, since they are diesilized gassers, so they are not very strong to begin with, so turboing a N/A engine almost never works out.

But the XUD family is a bit tougher I think. Although the XUD and XU gassers are related, I think they are not like VW (make a gasser, convert it to diesel badly, produce it for the next 20+ yrs), but rather a family sharing similar mountings/architecture etc, but the XUD was designed as a diesel from the ground up, its not just a dieselized XU, right? So its tougher (and certainly seems to be better then the VW 1.9D).
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Re: 1.8D vs 1.8TD

Post by Peter.N. »

I was never all that impressed with the Golf diesel, although it was ground breaking it was still agricultural, now the CX diesel was something entirely different, that really was refined.

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Re: 1.8D vs 1.8TD

Post by nametooshort »

I don't really like the Golf diesel family either, but unfortunately before I got to know French cars, its all we had to play with when it comes to euro diesels. The late 1.9TD engines are not so bad I guess, but have more problems then other engines of a similar age.

Then there is the weird 5-cylinder Audi engines, like the 2.4 that T4s got. I can't make my mind up about that. It should be a really bad engine, because it started out as a 6-cylinder gasser, then Audi decided that Europeans are too cheap for 6 cylinder cars so they removed one cylinder and made a inline-5 cylinder, which is kinda odd but I guess worked. THEN they did the same thing they did with the Golf family, which is take a gasser and deasilize it, reasonably badly. But strangely the 5-cylinder n/a diesel is surprisingly tough. The turbo engine is not even so bad. They are still not great, but better then the Golf family diesel.

But by the looks of it the XUD family is way better designed and though out from day one. Just look at their oil filters, a VW TD engine has a huge oil filter, a 5-banger Audi engine has an oil filter the size of half a house, and the XUD has a tiny oil filter. Yet the XUDs outlive the VW engines by several times.
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Re: 1.8D vs 1.8TD

Post by spider »

The 1.8TD is a good engine, it still has the cooling jets under the pistons etc.

I'll fish out some data later if needed.

Can be found in early 405's (pre 93 usually) 309's, 205's amongst others. A 205 / 309 donor might be OK if you wanted a 1.8 opposed to a 1.9 as they only had the 1.8 unit in turbo form as far as I'm aware. The 205 lacks the intercooler / pipework for it so depending on what you plan on doing ;) that might be suitable.
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