He said, " the H116CP piston which has a taller compression height"
I wasn't asking about the H116 pistons. I was asking about the 405p vs the h405cp.
The only way to get higher compression with a piston are increasing compression height, decreasing a dish or adding a dome.
I understand that. That's why I was asking about differences in those two aforementioned pistons.
The difference between the 405P and the H405CP is the 405P is older and out of production. I'd take the newer piston any day, even though it's probably made in India. The material is better, as is the coating.
I finally got ahold of federal mogul. The 405P are still in production. Besides the obvious design difference (dished vs 4 valve relief) and material type and coating, the H405CP pistons have a higher compression distance than the 405P (1.637" vs the 1.576"). Thanks for your input.
Does anyone know what the dish volume of the stock pistons is? I've never measured one.