Should I polish the tops of my pistons?

[Calan]

When I got my short block back from the machine shop, I noticed the pistons are engraved on top with small ID numbers. I was thinking about carefully wet sanding them with some 320 and higher to try and smooth it down to avoid hot spots. I think I can do it without getting any crud down around the rings if I'm careful. One of the pistons has a small shallow gouge as well, like the engraver slipped a little.

Good idea or not?

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[ninesixtwo]

Leave it, there is no reason whatsoever to sand them down.

 

[Calan]

Leave it, there is no reason whatsoever to sand them down.

Seems that they would be a source for some hot spots to form. You can definitely feel the surface irregularities.

I have no idea why they would be stamped on top like that.

 

[bling5tatus]

that's being entirely too paranoid... if that were the case 95% of all builds if not 99.9999% of all builds would have this issue when using those types of pistons.

Seriously, if you run your car and something breaks you will NOT be able to blame it on hot spots caused by the piston mfgr's engraving...

 

[Calan]

that's being entirely too paranoid... if that were the case 95% of all builds if not 99.9999% of all builds would have this issue when using those types of pistons.

Seriously, if you run your car and something breaks you will NOT be able to blame it on hot spots caused by the piston mfgr's engraving...

Who said anything about blaming anything on anyone if something breaks? I just want to eliminate any potential performance hits while it's easy to do, if it is worth it.

If there is no way that those surface irregularities could attract carbon and affect the flame front, then great. But since I don't know...that's why I asked.

 

[JEFFREYCASTGSX]

Who said anything about blaming anything on anyone if something breaks? I just want to eliminate any potential performance hits while it's easy to do, if it is worth it.

If there is no way that those surface irregularities could attract carbon and affect the flame front, then great. But since I don't know...that's why I asked.

Just dont worry about it.

 

[ninesixtwo]

Seems that they would be a source for some hot spots to form. You can definitely feel the surface irregularities.

I have no idea why they would be stamped on top like that.

They're stamped on the top like that because it's the best place to make identification marks on a piston. If you think you know better than Mahle, one of the 3 largest piston manufacturers on the planet, then go ahead

 

[Calan]

SHEEESH people... I was just asking.

I never said it was a problem, I never said I was worried about it or planning on finding a place to lay blame if something fails, and I sure as hell didn't say I knew more than a piston manufacturer.

Back in the day some of us would polish and debur everything, just to do it the best we could and to wring the last bit of performance out of every inch of the motor possible. I was simply asking if it would be worth the effort in this case.

Maybe a mod can just delete this entire thread and we can all just pretend I didn't ask such a controversial question.

 

[toofast82]

I would just leave them alone as said. They are not going to cause any issues.
If anything, you may do more damage then good

 

[bling5tatus]

SHEEESH people... I was just asking.

I never said it was a problem, I never said I was worried about it or planning on finding a place to lay blame if something fails, and I sure as hell didn't say I knew more than a piston manufacturer.

Back in the day some of us would polish and debur everything, just to do it the best we could and to wring the last bit of performance out of every inch of the motor possible. I was simply asking if it would be worth the effort in this case.

Maybe a mod can just delete this entire thread and we can all just pretend I didn't ask such a controversial question.

Well you got defensive about the answer when I was just giving what would be a typical scenario for someone that is maybe overly paranoid about their car. I do it too. When something breaks I immediately blame it on something I did wrong.

 

[need2boostpsi]

its not a bad ideal, a polished piston would help with carbon buildup over time, and maybe hotspots if your pushing your AFR to the limits, but a freehand polish i would not recommend especial since they have already been installed. you run the risk of doing more harm than good because you cant be 100% sure that no debris has settled into PTW clearance area.

 

[Clutch GSX]

If they were out of the block and not ringed I would do it just for the hell of it but no big deal if you dont. It's not like they are super sharp, thin edges.

 

[awdmonster1904]

^^+1

 

[Rob10_99]

YES, use scotchbrite on the top of the pistons. no sharp edges.

Clean it without getting residue into the rings.

 

[bling5tatus]

I wouldn't do this w/o being able to make the surface even either.... and removing material from the dish is lowering your compression as well.

 

[Clutch GSX]

There is no point to having a perfectly even surface. The amount by which you would lower compression is microscopic and meaningless. It would have absolutely no effect on compression unless you went crazy and started grinding with stones or heavy grit sand paper to remove the entire stamp.

 

[bling5tatus]

Hey some people like to be "complete" when they do things like this, I don't want a lop sided weight distribution on a piston that's going to have a long service life of revving to 8500k... do you?

 

[My1GLaser]

If you want to clean them up and are meticulous then it should be fine. Just put masking tape around the perimeter of the piston so that nothing can get in the PTW area or any of the holes in the block. Then clean off the tape before you pull it off.

FWIW, I sanded the sharp corner off the valve reliefs on my Wisecos. (I didn't touch the outside of the relief near the ringland because they are dangerously thin to begin with.)

If you take your time and don't go crazy it should help some, though I don't know how much. While you're at it, you can benefit from doing the same thing to the head CC area.

Just be smart about it.

 

[Clutch GSX]

Your piston isnt going to be lopsided because he polishes the serial number on the piston. I would polish the valve reliefs because they can be sharp enough to cause predetonation.

 

[toofast82]

I honestly wouldn't bother touching them! I couldn't possibly imagine there would be any noticable real world difference.
I would be more concerned with properly breaking in the engine, this has had good reviews from many on this forum and it makes plenty of sense
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

 

[mosul210]

I would be more concerned with properly breaking in the engine, this has had good reviews from many on this forum and it makes plenty of sense
Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

Wow that procedure is so controversial, it goes against everything I've ever been told in regards to breaking in an engine. Interesting read.

 

[dsm-onster]

It's not controversial. Automotive manufacturers for years have said to run the motor up high in deliberate, short, and taxing sperts to properly break in the new vehicle motor. A machine shop that tells you not to is afraid of their work and is wanting you to eak by until the warranty has lapsed.

Craig, I applaud you're attention to detail But don't sweat it. Even if you can polish away the stamping, you'd be removing enough material to need the pistons rebalanced, IMHO. Nice Wisecos!

There's going to be a much hotter spot on the 90* points of the sparkplug electrode than there, by far! If the stamping WERE a hotspot, it is also rather close to the initial flame kernal. Very minimal detonation chance. Guys get in trouble when their valves kiss the piston rim (far away from the kernal) and make hotspots there where the valve reliefs are.