I was just wondering what my max boost would be off of 93 octane. I have a s5 t2 engine with currently the stock turbo(I'm upgrading later), but someone told me that 15psi off of pump gas is the max I can get but I've seen other people run higher numbers.

 

I wouldn't say you have to worry about the octane number just yet. I would be more focused on the max boost your turbo can pump out safely and if you've got enough fuel to match that boost. If you find you want more boost, you'd find you'll want a bigger compressor side to pump out more cfm rather than boost. Then upgrade the fuel systems. I would say 15 psi is the max efficiency you can get out of the turbo. There's cars running 500hp on 93pump.

 

Like the above post said, don't worry about octane in the gas just yet.. you can get away with plenty of boost on pump gas as long as the you tune it properly.

I have a friend running 26psi on a GT40R on a 13b.
I have ran 18psi on a 60-1 hybrid with no pinging or detonation on 91 octane.

 

ive seen 20psi on s4 engines because of the lower compresion.
(not shure if they were using water injection or meth)

 

Well, I was wondering this for when I upgrade the turbo, I won't be going over 12psi with stock turbo a TMIC