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So I dropped a summit forged pro LS piston on floor like a moron.... There is a very slight bump that I can barely feel with my fingers. There was a very slight dent and scuff on the top corner by the bump that I was able to smooth out. I am doing a pro charger build and this could see anywhere from 600hp at first then maybe 800hp if I get boost happy like everyone seems too.
Do I need to replace it or is it fine? Does anyone know if I can buy just 1 Summit Pro LS piston?
Pics are grainy and I can’t see any marks. Maybe circle the issues with a sharpie and re-post. I’d bet you have nothing to worry about honestly. You don’t have coatings to deal with, so I’d sand smooth any sharp edges, clean it all back up really nice and send it.
Hopefully these are better. Circled the spots and also a picture of one side that is normal. It's not going to be a purely weekend warrior either I want to be able to drive it regularly 2x-3x times a week and last.
Scuff Very small dent. Normal undamaged side for comparison.
No biggie. Take some 320 grit and sand smooth the cylinder-side of the damage. Won’t take much. All you want to do is make sure the piston-to-wall clearance is where it’s supposed to be. Make sure you clean the piston after your done. Take the rings off and scrub it with soap and water. Air blow it dry. Clean rings the same way before you put them back on. The sanding grit if left will eat the cylinder alive.
That particular part of the piston is a lot smaller in diameter than the rest. Other than the obvious, just make damn sure the ring doesn’t stick in the land and you’ll be fine.
As forgiving as aluminum is, I doubt there is any real damage beyond the visible.
As was said, file away anything outside the original dimension envelope, smooth it over, and SEND IT.
If I smooth everything out I have to assume that will affect the rotating assembly balance by at least some number of 10ths of a gram? If I get a new piston that would also effect rotating assembly balance?
Can I make sure all the pistons weight the same without getting it all balanced again? Do I need to just get it all balanced again either way?
I am might be overly obsessing a bit but I want everything to be right.
If I smooth everything out I have to assume that will affect the rotating assembly balance by at least some number of 10ths of a gram? If I get a new piston that would also effect rotating assembly balance?
Can I make sure all the pistons weight the same without getting it all balanced again? Do I need to just get it all balanced again either way?
I am might be overly obsessing a bit but I want everything to be right.
You would have to remove a whole bunch of material to change the weight of the piston. Don’t worry about it... run it.
I measured to make sure the piston was still round at that top lip above the first ring land. It was within 0.0001 the accuracy range of my micrometer. I was also able to smooth it out with 500 grid and polished smooth with a leather rag. The weight seems to have change by 0.1 gram but I am not so sure it really did. Since the is the accuracy range of my scale.
You can just barely feel a really really small bump now. If you weren't looking for it you probably would never know.
I am probably going to run it. I can't imagine this being an issue at all anymore.
Yeah well I then took all the piston and rods apart cleaned and re weighted everything.... Weights still look good. Waiting on new spiral locks and a non plastic spiral lock tool. Good thing I did because I found a bunch of tiny pieces of plastic in the locks and around the wrist pin from the spiral lock tool. Would have likely found it's way to the cylinder walls.
Dropped summit pro LS piston on floor.... 
