I am curious what difference in detonation resistance when going from 89, to 91, to 93? Basically, what cranking compression can each handle? I know this is dependant on a number of factors, so individual experiances as well as generally accepted. Info is appreciated. My specific combo is a 408 EQ Magnum headed (iron) smallblock, 10.1 /1 compression, dual plane airgap, 235@ .050 intake duration cam in at 105. My timing curve is coservative, enitial about 18* , total is 30* at 4,000 rpm.

When does the intake close?

At .050, intake close is 44.5 degrees. Advertised (Comp cams whiplash series) is 72.5? Cam is 291 advertised, 235@ .050, in at 105. Hydraulic roller.