Why do you see loads of RST's that run 20 + PSI to get 230 - 250 bhp and then you get others that run 16 - 20 PSI.

Is it the way the tuner sets up the car or do some cars need that boost to make the power.

 

Are all the cars running low boost actually making 250bhp?? Loads of variables though to be fair, spec of turbo/head and the engine in general, and as you say setup especially on efi where you can maximize the efficiency of everything. There is a point, especially where turbo's are concerned that you can wind the boost up and make little or no difference in bhp, maybe a bit more torque and i'm sure some people just run as much boost as the turbo will make in the hope of squeezing out a bit more bhp.

 

I know of mine making 205 @ wheels (231 an 240 bhp @ fly) and jamboRST's making 217 @ wheels which would be a genuine 250 @ fly.

Both under 20 PSI

 

my old onion made 157 bhp at 22 psi and 167 at 16psi once set up,
but u cant beat the sound of 20+ psi whooosing thru the zorst

 

id be interested in this as,i want to get a T25 ball bearing for my s2,think it can handle 23psi max although wouldnt want to put that through it,more likely 18-19psi you see rsts running 18-psi chiped cam etc getting 195bhp,does that mean i would only achieve a similar amount even if i had forged pistons,steel block cam etc.
im after more torque anyway would love 220bhp-280ib/ft torque

 

Genuine figures?
Management used?
Engine spec?

Loads of variables

 

It's down to the VE (Volumetric Efficiency) of the individual engines, how well they can get gasses in and out.
The more restrictive, the higher the boost will be to make the same power as a car that breathes better.
Big valves, ported heads, high lift cams, large turbo's, all make for a better VE and so lower the boost reading.

You must remember that boost is relative to your engines VE and target BHP, you do not 'choose' your boost it is the result of what BHP you want and your engines spec.

 

I think it's down to some tuners having magical talents, with the ability to extract massive amounts of power with very little boost.

Seriously, it's down to the C/R that governs how much boost you run really. 2 different approaches to roughly the same thing.