[JoeC]

From what I read, the ZL1 block was used for the road racing GT Corvettes and performed well where max rpm was around 7000. When Jenkins ran his drag racing motors up to 8500 rpm the ZL1 power curve would drop off more then an iron BB. The theory was that the iron sleeves of the ZL1 block would "move" at high rpm causing poor compression sealing and less hp. Jenkins switched to the stronger CanAm block which used the 4.440 bore Siamese cyls and a destroked crank to get 430 cu in. The larger bore opened up the valve area and made more hp. The CanAm BB Chevy motor also dominated CamAm racing beating Ferrari, Porsche, and Ford, who all had more expensive exotic engines, until Porsche went insane and built their duel turbo 1100hp 12cyl.