Comments on: Small end lubrication (2) http://www.ret-monitor.com/articles/983/small-end-lubrication-2/ Specific mission-critical info for professionals Mon, 21 May 2012 23:11:06 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Terry http://www.ret-monitor.com/articles/983/small-end-lubrication-2/comment-page-1/#comment-6156 Terry Thu, 20 Jan 2011 04:55:02 +0000 http://www.ret-monitor.com/articles/983/small-end-lubrication-2/#comment-6156 4-stroke wrist pin bushings operate mostly in boundary contact conditions. So drilling the rod beam to feed oil to the bushing would only be helpful if additional cooling was required. Otherwise it would not improve the performance of the bushing. Normally, most of the flow to the wrist pin bushing comes from the rod bearing oil flows squirting out the gaps between the rod thrust faces and crank cheeks, and then being flung onto the piston underside. If you look at the picture of the conrod at the top of the article, you'll note there's a slot in the rod thrust face to promote these windage flows in the direction of the wrist pin bushing and piston crown underside. 4-stroke wrist pin bushings operate mostly in boundary contact conditions. So drilling the rod beam to feed oil to the bushing would only be helpful if additional cooling was required. Otherwise it would not improve the performance of the bushing.

Normally, most of the flow to the wrist pin bushing comes from the rod bearing oil flows squirting out the gaps between the rod thrust faces and crank cheeks, and then being flung onto the piston underside. If you look at the picture of the conrod at the top of the article, you’ll note there’s a slot in the rod thrust face to promote these windage flows in the direction of the wrist pin bushing and piston crown underside.

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