So this is a fairly stupid question, I know...but what are the limiting factors (besides the completely obvious) in terms of how high you can set boost? Obviously octane rating is key, as is how much the bottom end can handle...but what prevents someone with an MBC, TBE and tune from being able to safely run 23-24psi? Or is that safe?

 

The stock turbo can only handle so much, most people do around 21

 

My stock turbo handled 28 psi peak. Knock is your factor.

 

Exactly detonation is your problem not strength. Stock turbo is no where near the limits of strength with your motor. I dont run e85 like the post above me but on pump I run 25ish psi and 29-30 with c12

 

23 - 24 psi is relatively safe for an ix, generally speaking. when cranking up boost knock is the limiting factor, and eventually the efficiency range of the turbo comes into play.

 

I remember reading here that at 26 psi the stock head studs start to stretch.

 

i have not found an actual case where this has happend, im not saying it hasnt, but i havent found any hard evidence on it yet.... anyone have any?

the rod bolts will most likely go before the head bolts do.....

 

Well you better erase it from your mind, because boost does not "stretch head studs" (they are actually stock bolts) . It's a pretty retarded misconception. Just like "backpressure creates torque"...

 

20-21 is safe becuase our cars run so rich from factory. but you can prob do 24-25 safely with a tuner that knows what they are doing. Stock head bolts will not stretch due to excessive amounts of boost, but rather detonation. so if you are no where near any knock, your fine

 

Two factors that limit boost:

1) Octane rating IE KNOCK
2) The amount of stress you rods and pistons can take

 

It's like a bunch of parrots are in here...

 

Knock ends up encompassing almost all of the limiting factors when it comes to boost level. Except when you near the actual area where you reach the HP limit of physical components.

 

I was just stating what I read here.....