Im new to NICOclub so i guess hi my name is Elijah.
Anyway im building an SR20DET and about to put in some brand new pistons!
So i measure the cylinders and they are all sized well, nice and round with very little taper everything is going well until i measured wall thickness (basically just looking for coreshift using an ultrasound). The machinist thats advising me told me that .0950" was his limit for wall thickness and one portion on my 4th cylinder measures .0946" which is no big deal but i noticed alot sites want to sell 86.5mm pistons. (Some companies actually dont even make 86mm pistons i.e. Tomei)
1. I dont know where he got his .0950" number from
2. He worked on mainly American cars but knows alot about pretty much all cars.
3. If i did a .5mm overbore it would put that wall thickness at .0750"
(sorry for using standard and metric numbers)

So the final question is:
Does anyone with credentials know if the stock cylinders/block can handle being .0750" thick?
Note: Im talking about the distance from the inside of the cylinder to the nearest cooling jacket.
The cylinders dont have much wear so i would essentially be taking .5mm off the stock sleeve. Im hoping to end up around 400hp. Theres also a possibility im just being way too cautious.

if anyone can help, im still checking back everyday. Im probably going to end up buying stock 86mm JE or CP pistons.

What kind of power are you shooting for? Aftermarket forged slugs makes me think it's a healthy number.

Location of the thin area in the cylinder also matters. On the thrust side in the middle would have me the most concerned. On a pin side closer to the bottom, less so. Block cement might be an option...

Im aiming for 350whp with almost no headwork but i want to leave room to go higher later (500? After i get used to driving with 350). Maybe i will make a build thread but for now ive decided not to sleeve (Mainly because ive never heard of anyone reporting significant power loss due to not sleeving). The wall thickness issue is on the 4th cylinder near the bottom on the non thrust side but in general that entire 4th cylinder has alot of pretty shallow spots.

One of my first built SR20's encountered a thin wall problem. It was a blacktop S13 engine, and I tried to have the machine shop bore the block for the CP 86.5 pistons I provided to him. The day he bored it, he called me out to the machine shop to have a look at a possible problem. I glanced down into the bore after he finished honing #1, and you can see the thin sleeve area at the middle to have a wave appearance like it was made of foil, but touching it was smooth like the rest of the cylinder. He tried using a small magnet in the area, and it didn't have as much magnetic pull versus the same magnet at the top edge of the bore. I told him to go ahead and just prep the block for aftermarket darton sleeves that I had handy for my race block. He said since I was not going to use the factory sleeves, he was going to bore out the #1 cylinder a little more to see how far off that odd area was. He probably got no more than 0.01" and we clearly saw aluminum at that spot. In short, I should have purchased 86mm pistons to save the extra machining and sleeve cost. I know not all blocks are created equal, but I hope this helps.

Definitely. Thanks for the input. Im pretty sure at this point that most SRs have pretty thin walls just for weight savings and then theres core-shift which, luckily, alot of japanese engine manufacturers are good at keeping to a minimum. I was considering sleeving but i dont have the tools (CNC) to center the darton sleeves.