does anybody know about how much hp can be gained on a b18b1 turbo with 6 psi of boost?

 

That's a very vague question, since so many things can affect the power output of a turbo setup. A major factor is the size of the turbo you decide to run. 6lbs of boost from a smaller turbo is going to make less power than 6lbs of boost from a larger turbo.

 

Im with Inspyral on this. A T3/T4 @ 6psi doesnt make the same amount of boost as a G20 or t66. Different turbos have different CFM flow rates. It depends on several different things. Sorry if this is not of much help.

 

under 50

 

It could make you 40hp, it could make you 100hp, IT ALL DEPENDS ON THE SIZE OF THE TURBO. What turbo are you looking into getting, lets start there. It also depends on if your gonna be running 6lb of intercooled air, or 6psi of non intercooled air. Your gonna get different hp off the same turbo even if you intercool it. There are so many variables in a turbo set up, and so many different turbo kits that your gonna get different results more times than none. http://www.importreview.com/d_turbo.html look at that site there is a few dyno charts with hp for several GSR's running low amounts of boost. I understand yours is just the LS, but maybe that will help.

 

I dont understand why a larger turbo will produce more horsepower than a smaller turbo with the same amount of boost. Can you clarify why this is?

 

A larger turbo will flow more air(higher CFM) at the same boost level, and more are = more power.

 

Um... CFM influences boost pressure, they are not independent. The reason a larger turbo should provide more horsepower is because a larger turbo is capable of pushing the volume of air (CFM) at a higher level of efficiency than a smaller turbo.

The harder you push a turbo too small for a given application the lower the compressor's efficiency will be. Lower the efficiency, the hotter the resulting compressed air will be. The hotter the air, the less power can be produced with that air.

 

but if you go too big, you'll have big lag to go with it.

 

True. I forgot to include the other end of the spectrum: larger turbos = increased lag time. There are some benefits to be found in larger turbos, however, you just have to see them.

Bottom line is choosing the correct size turbo depends heavily upon your application. If you want to run autocross or street race, a relatively smaller turbo is your best option because it'll have a faster response. If you want to do full 1/4 mile runs or freeway racing, a relatively larger turbo is preferred due to it's ability to flow larger volumes of air for longer lengths of time.