Guest bigbadzcar99 Posted February 18, 2006 Share Posted February 18, 2006 Ok, I am building a hybrid engine, got all the parts together to build the bottom end this weekend. I got the new rings out to make sure they fit in the bore and on the lands on the pistons, and what do you know, the top rings are the wrong size!! I have a 1977 Z with stock block and bore size, all checked by the machine shop. But what I forgot is that the guy that had the car before me did some racing in it, and put flat top pistons with P79 STD stamped on them. Now I know the STD stands for standard size pistons, but after some research and using the search on this site, all I found was quite a bit of info on P79 heads. So, if anyone out there knows what year Z came with flat top P79 pistons, i would really appreciate it, I would like to get my engine together someday...Thanks for the help Quote Link to comment Share on other sites More sharing options...
technicalninja Posted February 18, 2006 Share Posted February 18, 2006 Nissan changed the ring thickness on the later model pistons. They reduced thickness to reduce internal friction as improved construction techniques allowed a thinner ring with the same sealing charateristics. This marginally increases power and economy as an engine internal friction has a greater effect than you might imagine. Take the pistons to the machine shop and have the ring thickness miked then order the correct rings. Most likely rings for a 81/82 NA ZX will work for you. Quote Link to comment Share on other sites More sharing options...
Guest bigbadzcar99 Posted February 18, 2006 Share Posted February 18, 2006 Thanks, i just went down and ordered a set for an N/A 82 280ZX. I figured that Nissan stamped there pistons to match the heads, so i found which engine had a P79 head and ordered those. The guy at the parts store told me that the Jap. spec 280zx had different piston rings then the U.S. spec. I didn’t know that, he said the U.S. spec used the thicker rings. Not sure if this is true or not, but that’s what his computer said. Anyone out there ever used the flat top pistons in a turbo app? should be higher compression, so require less boost for the same performance. I am using a P90 head on my hybrid Quote Link to comment Share on other sites More sharing options...
280Zen Posted February 22, 2006 Share Posted February 22, 2006 Thanks, i just went down and ordered a set for an N/A 82 280ZX. I figured that Nissan stamped there pistons to match the heads, so i found which engine had a P79 head and ordered those. The guy at the parts store told me that the Jap. spec 280zx had different piston rings then the U.S. spec. I didn’t know that, he said the U.S. spec used the thicker rings. Not sure if this is true or not, but that’s what his computer said. Anyone out there ever used the flat top pistons in a turbo app? should be higher compression, so require less boost for the same performance. I am using a P90 head on my hybrid[/font'] Too bad you didn't ask, I have a brand new set for the P79 head sitting in my garage collecting dust. Quote Link to comment Share on other sites More sharing options...
Guest bigbadzcar99 Posted February 25, 2006 Share Posted February 25, 2006 Figures, they whree only 45.00 at the local auto parts store. No big loss. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.