I want to turbo my "stock" b18b block. How much boost can the block safely take

 

It's not the just the block you must look at, it's the CFM of the turbo you're going to choose. If it is a hybrid turbocharger, about 7-14psi on various CFM turbos.

PM me if you need to understand the the right turbo for your application

 

you should focus more on the amount of hp as your goal and not the amount of boost. 7 psi can give you 200 horsepower or it can give 300 hp depending on the size of your turbo, downpipe, etc. People have been boosted on stock blocks of even up to 350 whp. If I were you, 300 would be good with a conservative tune.

 

thankx, I just got rid of my WRX and once you go turbo it's hard to go back