Re: Alfa Romeo 156 2.5 V6 24V Q-System - Automatic wont start
As far as I know it should work fine. The 3.0 engine mates with my 2.5 gearbox perfectly, just as if it was a 2.5, so I assume it must be the same for the auto.
The 3.0 has about 30bhp more as standard, but a fair chunk more mid-range torque. I think the mid-range torque is the reason why the 166 driver's tend to find the 2.5 and 3.0 return exactly the same fuel consumption - the 2.5 needs working that bit more to progress than the 3.0.
Finding an engine locally will be difficult enough in the North of Scotland, so unless you are transporting/towing the car to England for the work then I wouldn't be picky about whether you get a 2.5 or 3.0 engine. They're worth roughly the same, and are practically the same besides the capacity, so the cost of installing it will be the same whichever engine it is.
I didn't own my car when it was a 2.5 by the way, but I have driven a 2.5 and mine feels a lot better. But my 3.0 isn't standard either, which might account for some of the extra performance..