Oil clearance needed for drag race motor using thinner oil

[racinvrxse]

I'm rebuilding an engine that I would like to spin to about 11,000 to 11500 rpm. The idle is set at 2000 rpm and the operational range will be from about 7000 to 11500 rpm. The max oil pressure is about 95 psi, and the oil volume flow is 8.4 gpm at 5000 rpm and 16.5 gpm at 9800 rpm with synthetic 20W-50 motorcycle oil (specific gravity of .8800 @60 degrees). There seems to be an oil pump (gerotor) cavitation issue starting at 9800 rpm with this 20W-50 oil, but there may be a new design out next year that will output more volume and not cavitate.

I hope to maybe try running a thinner oil (synthetic 5W-20 motorcycle oil with specific gravity of .8650 @60 degrees OR synthetic 5W-30 motorcycle oil with specific gravity of .8597 @60 degrees) which should raise the cavitation point of the pump a bit, but I realize I will have to tighten up my oil clearances on my main, rod, and camshafts as well to prevent oil whip and premature bleeding of the oil. I'm not yet sure what my stock bearing oil clearance was, but I will be checking that soon. The general rule for these motors while running synthetic 20W-50 oil is .003" or .0015" all around the journal's perimeter.

I realize that this not a single formula, but how do I calculate a new clearance to tighten this up for running thinner oil?

 

[berkshire]

racinvrxse

You might be better off posting this in forum71, and either redflagging this post or mentioning that you have cross posted it in this forum.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[racinvrxse]

Good idea, thank you sir!