S50b30 turbo Piston ring gap?

[E30s50dude]

I'm currently building the bottom end on my s50 swap e30, and I'm curious on what piston ring gaps everyone is running for high hp set ups. My goal is 750 whp on e85. I'm running 22rpd 86mm pistons and eagle H-beam rods.

[Hova]

Nothing really special about our motors. All of the pistons manufactures are aware of their specs and recommend what generally works well for as broad of a range as possible. You're talking about making 120hp per cylinder, people have run 200hp per cylinder with the standard specs piston companies put out. This is a well understood area of science (thermal expansion).

There aren't many companies that make pistons for these engines. Wiseco, CP, JE, Mahle. Those look just like JE pistons with HD wrist pins.

There should be a sheet in the box with the pistons for setting ring gaps. Follow what the sheet says. If there isn't a sheet, just as a reference point:
I set my JE pistons to .0060" x bore on top, and .0063" x bore on the bottom. There is a mark on the ring that defines up btw.

Wiseco says a bit more gap, they like their rings at .0065 x bore and .0070 x bore.

https://www.jepistons.com/PDFs/TechC...instrc4032.pdf

http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

[E30s50dude]

Thanks for the info I did receive a sheet for ring end gap. These are JE pistons I spoke with Zack and he recommended going with 18" on top ring, and 20" on secondary rings. This is what i'll be going with but I do appreciate the input.

[Hova]

Thanks for the info I did receive a sheet for ring end gap. These are JE pistons I spoke with Zack and he recommended going with 18" on top ring, and 20" on secondary rings. This is what i'll be going with but I do appreciate the input.

That seems a little tight compared to what JE says to do: .02" and .021" for 86mm.

But I'm not a professional, I'm sure Zack knows much more than I do. Best of luck no matter what you choose.

[E30s50dude]

After gapping first rings to .018” I opened it up to .019” secondary rings were already at .022” so I’ll leave it there, and hope for best thanks for the response Hova.