What is the max boost i can run with just a walbro 255 pump 21psi or can i actually run a little more than that.

 

need more info

do you have injectors, cams, etc.

 

max boost has more to do with fuel and tune than the fuel pump.

 

+1

Your maximum boost level is determined by many factors, It all depends on how much air and fuel is going in and out. Boost is only the added pressure in your manifold from turbocharging it(this is on top of the 14.7 psi normally from atmospheric pressure). There are a number of ways to run different boost levels and still achieve different numbers. Timing, displacement, AFR, intake temps, its relative to many things. What is it you are ultimately trying to do?

 

What did your tuner say? That's where you should set it.

 

Unless your tuned for your Walbro its not being used to its potential. As the others have said there are several factors. the main one is of course the oct. of your fuel. 93 i would say your good for 21-23, 91 i would say dont go higher than 22.

 

What are all your mods? and what are the ones you have been tuned for? do you have a boost gauge?

 

IIRC, El Centro means 91 Octane, which means that 21 psi is about it (assuming a good tune), unless you've got an Evo IX.

l8r)

 

21-23 psi, is that what it spikes to, or what it tapers to and holds?