I was wondering if anybody knows it the n18 pistons are the same in diminsion as the n14 pistons I know they are both 77mm and that the block is the same. but are the n18 pistons the same as the N14's aside of the to relief cuts on the exhaust side of the piston. Looking to swap them in a N14 if possible. Due to clearance issues. Which would be the head having been surfaced to the maximum and really not knowing if the block was surfaced before I bought the car. And wanting to retain 10:5 to one compression ratio. and not really believing it is just as easy as putting on a .120 gasket. and not wanting to repeat the picture below because I just got a lot of head work done.

 

As you mentioned, I believe they are the same minus the exhaust cuts. I think I used one N18 piston on N14 engine to cut down on spending. I also would not be surprised if the N12 & N16 pistons are the same as the N18.

you may check realoem.com for comparison too.

 

N12 & N16 pistons are 11.0:1 CR.

Consider grinding down the valve dings on each piston, to create more clearance. Need to re-balance them, but it can be done. That's what I did with mine during my last re-build 2K miles ago --- trying to salvage custom CP's after the crank bolt loosened. Still running strong.

 

That's good advice. I know supertech started selling four valve relief pistons. and my problem I think is a bit beyond the timing. valve train float. I had already used one brand of new lifters(melling) in the head with new vavle springs, etc...
I just had the head re done with different lifters and new valves. I think it is just a combination. BUT I might be wrong but I refuse to do a 2500 mile break in and firming believe what is rebuilt can go directly to the dyno type of person. So I will use some of the new stuff I bought pretty much everything and some of the old. I just need it running and it should not be too much to ask.