4 replies to this topic

[Nev]

I am currently running 18 PSI steady boost on an Astra VXR Turbo (peaking to approx 21 PSI for overboost). I think this is slightly low as its was one of Courtenay's first stage 4 conversions and they may have reduced it slightly for safety margins (can anyone confirm they run more steady boost with this turbo?). I am tempted to tweak the actuator adjuster nut to get maybe an extra PSI (and hence approx 7 BHP) out of it - anyone got any comments ? Whats the max boost this thing can push out at 6000 revs without melting ?

Edited by Nev, 02 March 2009 - 08:34 PM.

[John Faulkner]

I am currently running 18 PSI steady boost on an Astra VXR Turbo (peaking to approx 21 PSI for overboost). I think this is slightly low as its was one of Courtenay's first stage 4 conversions and they may have reduced it slightly for safety margins (can anyone confirm they run more steady boost with this turbo?).

I am tempted to tweak the actuator adjuster nut to get maybe an extra PSI (and hence approx 7 BHP) out of it - anyone got any comments ? Whats the max boost this thing can push out at 6000 revs without melting ?

you might be OK nev, but i'm not sure i'd risk it, i know that on the astra VXR, with better cooling & flow 320-330bhp can be achieved with only 0.8 bar (11.6 PSI) of boost. i'm sure someone more informed will be along in a minute though......

[John Faulkner]

Nev, are you running a standard VXR actuator? i think an uprated one is needed/highly reccomended once you get to the 300bhp mark.... that would hold boost a bit better.

[Duncan VXR]

Uprated actuator prob needed if you don't have one - you need to pressure test your current setting - your wastegate should start to creep open at 15psi - the ECU / boost solinoids control the rest. Be carefull as you are not monitoring AFR and this is what will kill your engine - you may end up running lean! Mine used to hold 18psi and spike to 23psi on std vxr turbo and uprated actuator John may have one spare for sale he got off me

[daggles]

After my TMS S4 map.. With my boost switch in the off position the VXR actuator spring held 8 psi on it's own. Switching the boost back on gave 22psi over boost dropping to 17 over most of the rev range. I've since tightened the actuator nut a few turns and now I get 10 psi with the switch off and about what I had before with it switched on so with the standard (VXR) actuator it doesn't look like you get much extra excitement from fiddling with your nuts.