The stock FA20 block it self can handle pretty much 500-700 HP if you upgrade the internals. The only reason people blow engines or make holes in their blocks is because a rod or piston breaks and launches into your block at 8000 RPM! So if you upgrade to some 1000HP rods and a low compression piston set for example 9.5:1 or 10:1 you'll be all set. Also don't forget about the valve springs and if you're passing the 400 HP mark, upgrade the crankshaft. Upgrade/replace the head gaskets and the studs also. Other than that, you'll be set for a 350-700 HP BRZ/FR-S/GT86!

I'm running 600hp at the crank and I have the stock crank, headstuds and gaskets. The cranks on these cars are forged factory so there is no need to upgrade it like the old ej.

Oh nice! Good to know since a new crank is very expensive 😅
Could you tell me exactly what you did to your engine and the internals to get to 600 HP? I'm trying to learn as much as I can

Just rods and pistons. There was nothing else available at the time it was built

Not if you put a turbo behind it :burnrubber:

Presumably the turbo would go before it?

It would be an awesome setup, but I didn't hear anything else about that Perrin twin charged FA20DIT, so will assume it blew up.

I have seen 752WHP on a stock casting sleeve.
The problem is they wiggle at around 500 causing gasket failure. You can fix this with bigger head studs and sleeves. If you want to go big don't push a limit or skip a corner trying to get the most on a stock casting. will only cause compounded issues for reliability