This chart shows the rubbing speeds of various rod and main bearings. Some magagines and engine builders would have you believe there's a big difference in drag between a large and small journal Chevy, for example. Ignoring hydrodynamics completely, the following charts show how small the variation is between the largest and smallest journals used on common American V8 engines.
rubbing velocity in feet per minute at 6000 RPM (100 revs/sec) common rods: journal journal dia. circ. feet fpm ---- ---- --- small 2.00" 6.28 .52 3120 ^ 283-327 Chevy 2.08" 6.53 .54 3240 | 2300 Pinto 2.10" 6.59 .55 3300 | 350, 400 Chevy 2.12" 6.65 .55 3300 15% Ford 302, 300-6, Olds, Mopar SB 2.20" 6.90 .57 3420 | 396-454 Chev, 326-455 Pontiac 2.31" 7.25 .60 3600 v Ford 351C, 351W, 351M, 400 ---- ---- --- large common mains: journal journal dia. circ. feet fpm ---- ---- --- small 2.25 7.06 .59 3540 ^ 221-302 Ford 2.30 7.38 .61 3660 | 283-327 Chevy 2.45 7.69 .64 3840 33% 305, 350 Chevy 2.65 8.32 .69 4140 | 400 Chevy 2.75 8.64 .72 4320 v Ford 351C 3.00 9.43 .79 4740 --- large Ford 351W, M, 400, 429, 460 some common main bearing diameters: 2.25 Ford 302 2.30 265-327 Chevy small journal 2.45 350-307-305 Chevy large journal 2.50 some Chrysler Hemis 2.65 Chevy 400 SB 2.75 Ford 351C 3.00 Ford 351W, 400, 429/460, Olds 455 3.25 Pontiac 455