360 Piston differences

Does anyone know the differences off hand between a 405p and H405CP speed pro pistons?

Is the only difference that the H405CP are hypers?

C stands for teflon coated skirt and H stands for hypereutectic.

Just FYI Speed pro also makes the H116CP piston which has a taller compression height and a smaller valve relief than the 405 as well. As I understand it 405's are basically a stock replacement piston giving roughly 8.0 compression, while 116's are closer to 9.5:1.

Thanks guys. So, are the measurements of those two the same? Same compression height? I tried calling speed pro, but they're closed this week.

He said, " the H116CP piston which has a taller compression height"
The only way to get higher compression with a piston are increasing compression height, decreasing a dish or adding a dome.

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.

Federal Mogul sells pistons in sets. If you wanted a single piston you'd add a W to the front of the part number, such as WH116CP.

R.

I wasn't asking about the H116 pistons. I was asking about the 405p vs the h405cp.


I understand that. That's why I was asking about differences in those two aforementioned pistons.



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.

I have the H405CP's & the 4 valve reliefs are 10CC & yes they are 1.637" CH