Who made the pistons for Mercury racing in 03?
 

I have a set here out of a03. I also have a set of replacement J E 's here. They look nothing alike

Serial # of the engine & model and HP info is need as it sure would help. All marine related stuff goes off of serial # not so much year model but that is helpful as well.

Om 905547 . It has 575 SCI cam and other parts but it is looking like the short block may have started off as a 500 efi by the looks of the pistons.

They could be Manely

Don't they look like trw's ? see pic

I do not have the info at home in front of me but at my shop. Anyways what I remember off the top of my head is that Merc Racing 502 based / HP 465, HP 500, HP 600 SC & the 572 HP 800 SC based used the JE forged aluminum. The earlier big blocks HP 425 / 454 CID and the HP 450 / 454 CID used GM forged aluminum. The HP 525 SC / 454 CID used TRW forged aluminum. IMO looks like that is what you have TRW pistons.

these look like a .030 replacement, however the dish on top is not exactly the same. same cc with 1 valve release but the pic looks like a little less "D" shape. What do you think about these?

http://www.summitracing.com/parts/sl...cp30/overview/

These look like the dish I have but they do Not make a 4.5 bore and neither have the skirt reinforcements like the ones I have

http://www.summitracing.com/parts/sl...3f60/overview/

Also looks like they are not availible from merc for $187 each but who makes them ? Here it the merc part number 798-841233T1. It looks like the stock bore is availble though

Here is a link to the ones I just purchased. 4.5 bore.

https://www.jepistons.com/Catalogs/S...placement.aspx