So why not use the S4 chain driven 4.2L engine? Which is 25% smaller in size, but puts out 340 horsepower? They put out 360 with a chip. Can't those engines be used?

 

So why not use the S4 chain driven 4.2L engine? Which is 25% smaller in size, but puts out 340 horsepower? They put out 360 with a chip. Can't those engines be used?

 

Yes, the AWN engine can be used, it's also a DBW unit.

 

The 079 series chain-driven engines are only marginally shorter than the 077 series belt-driven units. Width wise, they are the same.

As you can see from the 077 series engines I've listed, there are 340hp engines in 32V form, and 360hp versions in 40V guise too.

I haven't come across a chip that would give a verified 20hp increase on the 340hp chain-driven unit. I prefer the older belt-driven units, the blocks are physically stronger (079 series is lighter, with thinner walls). There have been reliability issues with the B6 / B7 S4 motor, (BBK) whereas the 077 series engines are very reliable.

The 077 series motors are a proven unit, with a Motorsport pedigree, which means they're over-engineered for road use - think back to the V8 DTM series, where these engines were used in the original Audi V8, from 1989 - 1994. Pretty much like the I5 turbo motor was over-engineered for road use, during the Group B era in the Ur quattro.

The 079 series chain-driven V8 has no such pedigree that I can recall.