Do you have a piston for that with a Duratec 89mm bore?
We only manufacture two piston sizes for the 2.0/2.3L Duratec. We produce either 87.50mm to replace the standard piston in a standard bore or 88.00mm piston so the bore can be cleaned + 0.50mm oversize. The reason we do this is because the standard liner, which is cast into the Duratec block has been specially developed by Mazda/Ford. We have looked quite closely at replacing this liner because we get regular requests for bigger bore sizes, there are several problems;
1. The liner is very thin, which allows it to expand and contract with the aluminium that is cast around it.
2. The modern Duratec engine has not been designed to be rebored at any time in it's life, therefore the thickness of this liner is calculated to be correct at the 87.50mm bore.
3. We made a decision due to the design of the liner to allow only the smallest of rebore sizes to rectify a small amount of damage to the liner itself, this was the reason why we picked 88.00mm.
4. If we were to increase the bore size greater than 88mm, the liner thickness would become too thin, in our opinion, and over time would begin to distort.
5. Many of our competitors have not, in our opinion, taken this into account and although your engine may run successfully for a short period of time depending on use, eventually problems will occur creating premature engine wear and eventually failure.
6. Several companies have been replacing the liners, when the original liner is replaced there are several issues; the thin construct and ridged shape means that a lot of material has to be machined out to remove the original liner. This then means the aluminium left, particularly between the liners is very thin. The liner that is then used has to be off a completely different construction as it needs to be more self supporting, which is fine as far as the liner is concerned but the issue that arises is the thin layers of aluminium that expand and contract around the new more rigid liner are too thin and expand at a different rate to the now more rigid liner so again initially the engine will run ok, but the feedback we get from customers who have tried this option find failure seems to always occur in the short term in high performance engines but this takes a little longer on a road based engine.
Although there may be a way of overcome the issues with replacing the liners, I believe the only way to do this successfully is to redesign the interior of the block completely, but this would be a very costly exercise and therefore should only be undertaken on turbo engines over 500bhp. It would actually be cheaper to replace the complete engine than it would be to carry this kind of work even when once developed properly.
So my suggestion would be to go with either the stock or +0.50mm version and if you are engine has more damage than that, that the block is replaced.