i was just needing a little guidence i was running a 13 54 gear last night at thunder valley and exploded my engine six laps later at 13 200 rpms i have bought another engine but the trans ratios are different so i am trying to figure out if i was running 12.3 overall gearing last night is up or down lower rpms
example 10.6 lower or higher rpm than 12.3? also in my book on this other engine has primary ratio and final gear reduction ratio witch one do i use when figuring out my gear primary is 1.565 and final is 3.00

thanks in advance for the help