I think my pocket calculator had a case of GIGO and that the radius should be
halved . The in pressure required would be 30 psi and the out pressure gain
would be 77 psi . At 7500 rpm the rod bearings would see incoming pressure
less 30 + 77 or a gain of 47 psi .
>My pocket calculator just told me some things I didn't know about getting oil
from the main bearings to the rod >bearings at higher rpm .
>Using the formula for centrifugal force .00034 x weight (lb) x radius (ft) x
rpm squared
>The weight of motor oil .0318 # / ci ( 7.34 # / gal div. by 231 )
>The radius .115 ft of a BBC main bearing of . ( half of 2.75" div. by 12 )
>The radius .248 ft from the axis to the outside of the rod journal of a 427
bbc (half of 3.76" + 1.1 div. by 12 )
>So at 7500 rpm it takes 70 psi to just push the oil to the center of the
crank but centrifugal force adds 154 psi >at the rod bearing . My 427 bbc
dragster worked fine at 7500 rpm with 60 psi oil pressure so outward flow
>must have sucked the oil in to the center of the crank . I wonder if some
combination of stroke , main journal >dia , oil press and temp and rpm , rod
bearing problems might not come from oil vaporizing at the crank axis ,
>especially with fuel on the oil . Does anybody know the vapor pressure of
motor oil at 200 deg .
_______________________________________________
Land-speed@autox.team.net
Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
|