I just bought some new SpeedPro forged pistons for my new engine build up. I noticed that these things have some pretty sharp edges on them, especially around the valve reliefs and along the bottom of the skirts. The sharp edges on the valve refiefs could easily be a spot for detonation to occur. I am going to be running nitrous and was concerned with this. I took a brush that my company makes and put it on a Bridgeport mill and ran the brush over the piston. I passed over the piston with two different grit brushes, the first pass was done with 120 and on the final pass I used 320. The edges are nice and smooth now with no sharp edges.

 

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This process took about two and a half hours and I feel it was definatly worth it.

 

Nice!

 

what kind of brush is that? plastic bristles with grit impregnated?

That's nifty. I was thinking i'd just use a small file on my speed pro hypers, might take a bit longer...

 

Yep you guessed it.
It is a nylon abrasive, just nylon impregnated with abrasive material. It worked perfect.
It still took awhile, I had to traverse the table and switch brush rotation. I think it would take too long by hand.