Hi
I've been thinking about using a NA 7A engine for my turbo project, are there any useful parts in the 7A?
What's the difference in a performance point of view between the 7A and 3B internals, piston oilsquirters, conrod strength, cylinderwall thickness, crank strenght etc.
What about head port and valve sizes?
What about using the diesel crank to gain some cc's?

I'm refering to the crank used in 2.5l diesel's available in europe in Audis VWs and Volvos.
(i think it's a 95.5mm stroke crank)

What's the "Eurovan" ?

So you are considering a 2.6L?

If you are considering the 7A to save some money, forget it. FWIW, I have a 7A long block sitting in my garage and have contemplated the same thing for a "big" engine for my ur q.

The 7A has an 82.5mm bore, so you would need custom pistons, as the 7A pistons are cast (not forged like the turbos), and have a flat top vs. the slight dish in the turbos to reduce compression ratio. The stock 7A crank should be fine, but if you use the 95.5 crank you will have to do some clearancing of the block and have the pistons' made with this crank in mind (raise the wrist pin height). You would want high strength rods like Pauter or Carillo if you have big hp in mind (of course you do...).

The turbos have a different coolant manifold for more even cooling of the head. The 7A head casting is essentially the same as the turbo engines, and you can modify the head to work.

For the money, I would go with a Euro Spec 2.6l long block with a tweaked turbo 20V head. You can't build a 2.6l for the price (unless you have incredible connections), and you don't need to do all the research because it has been done and works.

Once you have the 2.6l, you need all the supporting components, like injection system, intercooler, etc. to take advantage of the increased displacement. You are looking at a lot more $$$$ there...

HTH!

Steve
'82 urq 20Vt

...thanks for the tip!

Does the larger bore (82.5) means trouble, as in weaker cylinder walls?
Can i get reasonably priced hi performance head gasket with 82.5mm bores?

What about oilsquirters in the 7A block?

I THINK that the AAN metal head gasket will work, but I can't verify. Check with Euro Spec, they would know. The standard 3B gasket looks like it will support 82.5 or maybe even more.

As for strength, I was told by a machinist that the walls were plenty thick, even for a high boost turbo. Then again, I recall hearing from the folks at MTM that there is NOT consistently enough material in the cylinders walls for 82.5mm bores in a turbo. Sooo, have the cylinder wall thickness tested and try your luck I guess...

Yes, the 7A also has oil squirters in the block. BTW, these can be added to non-turbo blocks if necessary.

Steve