[HWYSTR455]

I pulled that chart right from the Procharger website, and honestly didn't notice it said for aluminum heads until you mentioned it! But in general, subtract a point for iron heads, would give you a rough idea. Maybe in other areas on the Procharger site you can find guidelines regarding iron heads and SCRs, I haven't looked in a while.

There are places on the 'net that give general guidelines for calculating DCRs, and supercharging engine theory as to what DCRs are acceptable when designing boosted engines, you could search it. I believe the general rule of thumb is 16-18:1 DCR is max on pump gas. The buick guys seem to have broken that rule and gotten away with it though, but it's a ragged edge.

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