Using the specs for the cvh 1600 i could find off the net I have worked out the rod ratios for both engines

CVH 1.65

zetec 1.58

As you can see the ratios are not all that different!

From this we can see that the cvh may have slightly lower piston / bore side loading, but bore wear has neve been an issue on a zetec so no advantage there.

Rod length can effect cylinder filling at different rpms and there for ignition advance figures and camshaft choice and will also effect torque characteristics, but the difference between the cvh and zetec rod ratios will simply not have that much of an effect.


As for bore wall thickness... if zetecs are not cracking bores at 400 bhp i cannot see it being that much of an issue. Bore flex and cracking is not simply effected by bore thickness. I think you will find block design and structual rigidity is has a lot to do wih it!