Bore size is 9.047 cm as standard, with a cross sectional area of 28.422 cm sq.
An 0.004 inch oversize is an additional 0.010 cm, so the bore size is now 9.057 cm. The new cross sectional area is 28.453 cm sq.
By ratio the new capacity is 2286 * (28.453 / 28.422) = 2288.5 cc.
Conclusion? Increase the bore when the cylinder walls become worn; not for additional power. You can only go so far before cylinder liners are required.
Jonathan Paton
Disclaimer: I've used the bore size and the engine capacity figures without knowing the geometry of the engine cylinder/head. I've never taken an engine to bits so I'm not an expert of any sort. Math/calculator mistakes are possible.
You must have a thick beard...40 thou is about the thickness of a hair.
40 thou is the maximum oversize piston and rebore. Once the bores need reworking again, they will have to be relined. The size will have no effect on power or torque - 40 thou is about the thickness of a hair.
Perhaps for the 2.25. I'm pretty certain that +40 is the max for 2.5s.My 2.25 diesel engine is overbored to 60 thou which I think is the max. I didn't do it. Takes wear out but its not a worthwhile performace upgrade. Cheaper and more effective to get a more powerful engine.