Hello,

My machinist left a piston ( Supertech P4-MA790-N10) out and developed rust and has small pits on top of piston. He cleaned it up and said "I wouldn't hesitate to use that in my own engine". The ring grooves have no rust/corrosion in them and looks to still have the phosphate coating intact. I plan to run between 8 to 20psi Max of boost on 93 Octane.

My question is: Will this piston be okay to use?

Thank you,
Drew

 

well aluminum doesnt rust, sooo. sounds like he has a filthy shop.

But that piston has already seen detonation.

The real question is- would the machinist use this in his/her own hi performance boosted engine? i dunno, maybe. I hate the word "maybe" when talking reliability of anything expensive.

 

Detonation on the side? Looks to be like it got exposed to some kind of salt and moisture.

He owes you a new piston.

 

You're right aluminum corrodes. It's a brand new piston.

 

I wish it was as easy as buying one new piston. Unfortunately, supertech vendor's only sell in kits of 4.

 

THATS A BRAND NEW PISTON? Holy hell, how many years did it sit in the shop exposed to the elements?

 

Yup, I would be buying a new piston. That one while it might be "Usable," why chance it?

Right now would be the absolute least expensive and easiest time to replace the piston.

 

Looking at it again, I refuse to believe that is a new piston. I can see the carbon and where it was "cleaned" with a wire brush.

 

Used is my guess. No way that would go in my motor.

 

What does the outside and underside of the skirt look like?

 

Brand spanking new piston. It sat in his shop for one solid *** year.
I wasn't in a rush because in that year span I was able to completely overhaul my miata. So now I just need to assemble this engine and drop her in.

He was recommended to me by 3 people so I went with him. Luckily he didn't screw up my oil tolerances, everything is money. However first and last time using him as he messed up this piston and my wiseco rings and it was a pain dealing with. I'm guessing it sat on the floor in the box and somehow water made it's way to it. I see the box had water on it.
I don't want to deal with him at all , so I'm going to just eat the cost on a brand new set. I already order again from Brad at Fab9.

Thanks for the replies Ryan.

 

You're absolutely right. I'm not chancing it. I ordered a new set.

 

I could show you some under skirt pics, but it ain't allowed here.

 

DUDE, your miata is clean AS HELL! wow...

 

Same. I figured I asked first before dropping more dough.

 

I'm new here, but I'll post all my photos in an album or start an intro thread.
Crazy thing is I got her for $500 on craigslist. She slumbered in this guys barn for 7 years. So it didn't look anything like it does now. Rats had fun with some wires and had a feces party all over her, surface rust here and there, but all the important areas in the chassis were good. The frame rails only had one incident with the road, but in general compared to others I've seen I got lucky.

Despite all that time she started up on the 2nd start. However, all the seals were shot on engine ...Now 3 years later I'm here .

 

And, I'd add that garage looks really nice and tidy too, (+2 for a nice prep job on your car!).

 

Pretty much equals my story. Only difference is that my chassis was rusty and we welded like an acre of sheet metal into it.
Got a new paint job and soft top, but mine isn't as clean as yours from the underside. Really well done

 

@tomrev Thanks guys. First thing before I took on this project was to stay organized , and that started with el garaje


I'm glad I did.

@der_vierte I need to see this miataaaa.

 

Lies, all of it. Piston is used, Miata is new.