Originally Posted by ZeeOSix
Originally Posted by beechcraftted
I once had a top fuel crew member explain to me why the pistons were replaced so often (they looked good to me as this one does). He stated that the very high combustion forces actually press the dome of the piston down, causing the upper ring land to close up. It has to be replaced before the top ring breaks. Note how far down the upper ring groove is compared to modern gasoline engines. That piston has lived a hard life.
Yep, that first ring groove is really down from the piston crown. Makes sense.
Is that 3rd wide groove down from the top actually for a ring, being that it cuts across the wrist pin?
Look at the pic I posted of the rack ready to be installed, from one of the past teams I worked on. It is for the oil control ring. The wristpin is inboard as you see in the OPs pic. What you can see installed in my pic are called 'buttons' which keep the wristpin centered. They are clearanced for the oil control rings.