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I am in the process of using offset grinding to increase stroke in a b20 in my 544. I got the idea from Dave Barton and Topi Hynenen. This lowers the bearing area considerably, but only on the rods . The old bearings are 2.13 x 1.062 and the news are 1.772 x .801 so that's about the two extremes of modern engine usage. Topi suggests on his web page that this will reduce oil temperature during hi-rpm race usage. I know from development of the Ford Windsor/Cleveland/Modified engine family into the Ford SVO race block, this was considered a critical issue, the larger main diameter was not acceptable in race usage, and all current blocks feature the smaller size. What is in question here is "relative bearing motion". That is, a crank having a 3 in bearing turning at 7500 rpm will see 70,686 inches of crankshaft circumference pass a given point in the bearing in one minute, a 2 inch will see 47,123 inches pass by. This is a linear relationship. You might look at it as the bearing speed of the 3in at 500rpm equals the bearing speed of the 2 in at 7500rpm. A further example is the buick 455 engine with what I belive is the largest passenger car main diameter: it has a very definate redline due to that factor. However on the volvo engines I see no reason whatsoever to change bearing area alone, I'm doing it because I want a displacement increase, and lighter weight reciprocating components.
Anyone who would like to discuss the 2392cc set up I'm putting together can e-mail me.
Ian
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