Why are there holes in V6 pistons tops ? (Page 2/3) 82-T/A [At Work] AUG 14, 01:25 PM I'm VERY intrigued about this still... I'm going to try to figure out what the answer to this is. olejoedad AUG 14, 10:37 PM From the Factory Service Manual... 82-T/A [At Work] AUG 15, 08:30 AM quote Originally posted by olejoedad: From the Factory Service Manual... Hey Joe, but this is different. When I disassembled my V6/60, the pistons also had that little notch on the side, which is directional and referenced in the service manual. BUT... we're talking about that hole that's drilled off-center in the middle, not the little notch on the edge/side of the piston. My V6/60 pistons did not have that hole drilled (I have one assembled on my bookshelf as a book-end if someone wants me to take a picture of it). olejoedad AUG 15, 08:44 AM Just posting info from the FSM, as you said, the holes are neither mentioned nor illustrated. StockGT AUG 15, 03:56 PM The two engines that I noticed the holes in the piston tops, were from 1988 Fieros. Fie Ro AUG 15, 05:24 PM My 87 pistons have the notch but not the hole. The notch is more like a rounded square with a slope and is cast. Raydar AUG 15, 09:05 PM quote Originally posted by StockGT: The two engines that I noticed the holes in the piston tops, were from 1988 Fieros. Interesting. I also seem to remember anecdotal stories about there being a change in compression height, over the years. Maybe that was also an 88 thing, since there were so many other changes. (Like internal balance, and CKP sensor provisions.) As many 88s as I've owned, I've never had the heads off of one. IMSA GT AUG 15, 10:08 PM Are the holes the same depth? If not, I wonder if these holes are drilled to remove material and make each piston the same weight. Patrick AUG 15, 10:24 PM quote Originally posted by IMSA GT: I wonder if these holes are drilled to remove material and make each piston the same weight. I'm not speaking from experience... but I'd suspect that any weight removal would be done on the underside of the piston. IMSA GT AUG 15, 10:35 PM quote Originally posted by Patrick: I'm not speaking from experience... but I'd suspect that any weight removal would be done on the underside of the piston. True.