I am about to do a full rebuild on my 1985 GN and was curious about which pistons to use. I'm looking for 12's. Should I bother going aftermarket? Should I do forged pistons, or use hypereutectic? Any suggestions would be greatly appreciated!!!
If you can reuse the stockers, definately use them. Hypers will easily meet your goals but are more sensitive to detonation although my dad had detonated the hell out of his T-type with no problems so far with hypers. Forged are the best but I would stick with something other than TRWs.
I would suggest using the TRW forged pistons, not the hypereutectics they are junk. We have used the TRW piston in 10 sec cars with no problems. If you need a price on some rebuild parts contact us at www.aggressiveauto.com or (586)771-9122
Maybe TRW has fixed the pin oiling problems but I know of my motor along with 3 other locals that had pins siezed up. One of mine broke the second ringland just driving normal down the street. That's more than enough to make me stay away from them. The pistons themselves aren't that heavy, just the pins.
As for hypers, I personally wouldn't use them but after seeing the abuse they've withheld on my dad's daily driver they can't be that bad. They will hold together in a 10 second car if tuned properly.
I went with JEs because it's cheaper to spend and extra $100 now then a rebuild later.
Don/t know about the current TRW pistons, but about 8=10 years ago they had no previsions to oil the pin. (I also had a set to GRAB the pin) A hole can be drilled on an angle from the oil ring groove over to the pin bore to force oil being wiped off the walls on the downward stroke to be forced on to the pin. Also need to open the pin bore .0005. I open the pin bore on hypers also. I have had great success with hypers, but with any piston,detonation will finally kill them.