Understanding Greddy Profec B Spec Ii Boost Controller

[Shinrai]

I have a R33 GT-R with a Greddy Profec B Spec II Boost Controller installed and I was wondering if anyone could help me to understand the settings.

I had my car dyno tuned and the boost controller set for 14 psi in high mode and 12 psi in low mode on the standard turbos. I initially didn't want to set the boost too high as I wanted to make sure that the turbo's would last.

However, I have decided on a turbo upgrade in the new year as I really want more power (HKS 2530's or HKS GTRS's).

I have read here that someone has the standard turbo's running at 15 psi...

http://www.skylinesaustralia.com/forums/in...t&p=1773956

Is this safe? Is it safe to push them any harder?

It was also mentioned in this post that after a month or two power dropped. I also feel this but I am not sure if I am just used to the extra power now. About 10 weeks ago I had a Haltech Platinum Pro ECU installed and it was dyno tuned at the same time. When I first got it back, it felt like a rocket. Now it still feels quick but it just doesn't give me the same experience. Keeping in mind that I have only owned this car for 3 months, it is definitely possible that I have simply grown used to the power. Any way to check for this or anything else that could be stopping the car from producing optimum power?

I would like to know how to set my boost to 15 psi without the help of a tuning workshop. Is this possible without any extra equipment like a dyno? If so, could anyone explain the process?

[Moodles2]

1 bar (14.7psi) is the most you want to run safely through ceramic turbos in bursts (ie. not at the track), the stock ceramic turbos are just handgrenades waiting to happen and can take an engine with them with ceramic dust.

Never used a jap boost controller, but you want to modify the duty cycle option slightly (leave gain alone as it's already tuned).

[Shinrai]

1 bar (14.7psi) is the most you want to run safely through ceramic turbos in bursts (ie. not at the track), the stock ceramic turbos are just handgrenades waiting to happen and can take an engine with them with ceramic dust.

Never used a jap boost controller, but you want to modify the duty cycle option slightly (leave gain alone as it's already tuned).

Didn't think of that... I was thinking that if I am going to upgrade turbo's soon, it wouldn't bother me if the standard turbo's died but I definitely don't want my engine going with it.

I think I might just leave it as is for now. I might just get the shop to have a look at it to determine if the power has dropped or not... I will give it a minor service soon anyway.

[JonnoHR31]

if its only 1psi more just turn the knob from the main screen whilst in hi boost mode and increase the value a couple % then press the knob. load it up and watch the boost gauge, if its too much drop it back a %, if its not enough keep turning it up. gain adjusts how hard it comes onto boost, too much and it'll spike. set gain is how much boost is needed before the solenoid lets the actuator see any pressure, best to have it set 2-4psi below your target boost, depending on how well your wastegate controls boost. personally i'd just leave it how it is until you get new turbos

[Shinrai]

Yes, I know it's only 1psi more but that's still 7% more boost. I was just thinking if it was easy to do, it might mildly satisfy my hunger for more power over the next month or two while I plan out/save up for the power upgrade.

I'm getting a minor service done soon, I might just get them to look into it for me.