Was interested in the 2.5L I4 Mazda engine used in the new Mazda 6 and an option in the 2010 Mazda 3. I was looking at the bore & stroke dimensions and was disappointed that it appears to be a stretched 2.0 to a 2.3 and finally to a 2.5 L. Most newly designed engines have a bore stroke ration of ~ 1 to 1 i.e 3.5X3.5 etc. It is especially importance in an I4 to strive for a shorter stroke because of the primary and secondary vibration produced by a I4 configuration. I now understand why the magazine described the engine as being course and noisy over the 2 & 2.3 L. Mazda has increased the stroke from a long 3.7 inches to 3.95 inches but only increased the bore by 0.080 inch. I think all Mazda did was to make a stroker crank and polish out 0.080 from the cylinders. I had hoped for a new sheet of paper or at least a new block with a Bore stroke ratio of something approaching 1 to 1. I guess they saved some block retooling money.(killit)
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