Piston identification please

[KevinB]

Anyone tell what these are? I know they are 30 over but does that number look familiar?
521acp
28207-15-b

 

[KevinB]

Looks like a speed pro hyoertechtic or however you spell it

 

[chopped39]

I have seen the acp before. I think that is a Sealed power piston

 

[baby6]

Speedpro, type the 521acp in google and summit will pop up.

 

[Paul Lohr]

http://www.fme-cat.com/PartDetailWindow.aspx?brand=SD&pt=Cast Piston&PartNumber=H521ACP#.UT2K_tZaJ8o

http://www.summitracing.com/parts/slp-h521acp

How did these pistons hold up for you?

I assume they weren't in one of your 9-second cars?

Paul Lohr