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Greddy Profec B Spec 2

SiR_RB

By SiR_RB,
in Engines & Forced Induction

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SiR_RB Grand Master

SiR_RB

Posted
Posted

Hey guys,

Started my car today and realised the (HI) symbol on the top left corner of my profec b was flashing.

Thought this was unusual as that normals stays permanently on, it does not flash,

I then go into (LO) mode and that's doing the same thing too, flashes constantly...

Even tried turning the unit Off and back on, still the same thing

Can anyone help me? Why all of a sudden the hi and lo symbols started flashing?

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https://www.sau.com.au/forums/topic/357598-greddy-profec-b-spec-2/
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Beer Baron Grand Master

Beer Baron

Posted
Posted

yeah i've had 4 or so in various cars of mine and never had a real problem with one. I found on GTRs with small twins that ramp up really hard onto boost they can't bypass enough air immediately and get a tiny spike but apart from that they are great. spike only lasts for a 10th of a second if that so it's not really an issue. when set up right they hold very stable boost.

SiR_RB Grand Master

SiR_RB

Posted
  • Author
Posted

alil off topic, but the 2 hoses that go from the wastegates then into a t-section that join to the boost control solenoid, is it recommended that both wastegates hoses be of equal length? my solenoid is mounted under the air pods, so naturaly the front turbos wastegate hose is shorter then the rear

would having equal length hoses make a difference in say holding/controlling boost/spool time etc?

cheers for the replys

Beer Baron Grand Master

Beer Baron

Posted
Posted

close to equal is a good idea. doesn't have to be exactly perfect but if there is a big difference it can have an effect. overall you want the lines as short as possible. unfortunately most people re-use the factor GTR set-up which has the solenoid a LONG way from the turbos (usually mounted on driver side near strut tower). mainly because it's easy to put there with the factory vacuum hoses and it's easy to get the wiring through the bung there into the cabin.

Don Dada Mentor

Don Dada

Posted
Posted

Yea i browsed through the manual and didnt see anything

I had my solenoid by the brake booster and used to get a little spike on gear changes so i relocated it to the passenger side by the strut tower and made all the lines as short as possible with equal lenghts to the actuators etc.etc. and did get a decrease in spike

As baron said with the quick ramp into boost a small spike is almost inevitable but they hold boost pretty good otherwise

One other thing i have to try is taking the pressure source from the twin turbo pipe but just hasnt gotten around to drilling and tapping it to take a nipple.....

Beer Baron Grand Master

Beer Baron

Posted
Posted

in my new car (32 GTR with jun 2.7, 230s, cams, motec) it has a profec b II that was set-up in japan. one interesting thing about this one is the profec B II is set-up with no 'start boost' setting. it just has the % number in (gives the boost level) and the gain number. surprisingly it still ramps up super hard. personally I always use the start boost to get the thing spooled up to near the target boost as quick as possible but it seems to work fine as is.

if you are having a play with yours try setting the start boost down to zero and see how it performs. it may cure any spiking problem and in my experience doesn't really increase lag at all.

SiR_RB Grand Master

SiR_RB

Posted
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Posted

with mine running at 18psi i have the start boost on 125 (12.5) and only seems to spike very little. some people say to run the start boost as close as the boost presure ur running or usualy around 3 or so psi less. mine spiked when the start was that close.

interesting to hear ur start boost was on zero? then again maybe running a 2.7L has something to do with it still been able to boost hard and quick?

Don Dada Mentor

Don Dada

Posted
Posted

in my new car (32 GTR with jun 2.7, 230s, cams, motec) it has a profec b II that was set-up in japan. one interesting thing about this one is the profec B II is set-up with no 'start boost' setting. it just has the % number in (gives the boost level) and the gain number. surprisingly it still ramps up super hard. personally I always use the start boost to get the thing spooled up to near the target boost as quick as possible but it seems to work fine as is.

if you are having a play with yours try setting the start boost down to zero and see how it performs. it may cure any spiking problem and in my experience doesn't really increase lag at all.

Yea i'm sure engine mods/displacement had alot to do with that plus i assume its 2530s with the upgraded hks actuators?

I guess i use the same method as you as I have my start boost just a few psi lower than the target boost and gain all the way down to lessen the spike but the spike is very small and quick so it doesnt bother me to tell you the truth and boost creeps just a few points of a psi as rpm increases

I'll experiment with that setting you mentioned above tho as i dont think i ever tried it that way and its been a while since i even touched that controller

Beer Baron Grand Master

Beer Baron

Posted
Posted

yeah sirRB, you're right, it's not always possible to have the start boost that close to target boost without spiking. especially with stock, or small twins like GTSS etc. mine would spike if i had start boost too close. it's just a matter of adjusting it down a bit or lowering the gain helps too.

yeah the 2.7 definitely makes it torqier off boost and yes it does have 2530s with HKS actuators (not sure what pressure they are set to). it may be that they set the actuators to crack at like 1 or 1.2 bar so there's no need for the start boost setting.

  • 1 month later...
SiR_RB Grand Master

SiR_RB

Posted
  • Author
Posted

So the "set gain" basically tells the actuators when to start opening? So the longer you can keep them shut, the harder the car will come onto boost?

But possible spiking may result if too close ?

I didn't know running a high gain will cause spikes too, I'm currently (with the cold weather) getting massive spikes when giving it full stick ! I tried lowering the set gain even down to 10 and even 5 but didn't get rid of the problem completely...will have to turn the gain down afew notches and see it goes

boostn0199 Grand Master

boostn0199

Posted
Posted

In regards to the flashing if its similar to the blitz its means its in edit mode and you can alter the settings if its not flashing means its in set mode. Personally I dont like playing with the boost controller myself and mucking around with the settings as its hard to get WOT in 4th on the road to test out what its going to boost to and if it spikes like you can on a dyno so I like to keep it as it is when it was tuned.

Beer Baron Grand Master

Beer Baron

Posted
Posted

So the "set gain" basically tells the actuators when to start opening? So the longer you can keep them shut, the harder the car will come onto boost?

But possible spiking may result if too close ?

I didn't know running a high gain will cause spikes too, I'm currently (with the cold weather) getting massive spikes when giving it full stick ! I tried lowering the set gain even down to 10 and even 5 but didn't get rid of the problem completely...will have to turn the gain down afew notches and see it goes

exactly mate. the set gain is set so that the controller will keep the wastegates shut up till the set gain point is reached, then it will start bleeding air to smoothly reach your target boost. if set gain is too high there is not enough time for the controller to start bleeding off air and stop the boost curve climbing before it reaches (and goes past) your target boost level.

try setting set gain to zero. do a full throttle run. adjust the gain setting until you still have a nice fast boost climb but no spiking. once you've got that sorted then re-introduce the set gain. if your target is say 1bar you generally can't have set gain any higher than about .7bar or so.

SiR_RB Grand Master

SiR_RB

Posted
  • Author
Posted

Cheers beer baron.

Target boost is 18ish psi with -7's

So far seems to be good, holding boost and not getting big spikes

Boost% 50%

gain 17

Set gain 125 (12.5psi)

Drops about one psi at high rpm, 6000rpm +

not bad so far.

Also wen u say put ur set gain to 0, wouldn't that mean max boost would come late and more smoother?

Beer Baron Grand Master

Beer Baron

Posted
Posted

yeah 1psi drop across the rev range from 18 to 17psi is pretty good.

yeah theoretically setting set gain to 0 means no pressure keeping the gates closed. didn't make much difference on my car as it has HKS actuators that hold closed a lot longer than stock anyway.

SiR_RB Grand Master

SiR_RB

Posted
  • Author
Posted (edited)

ok had a run on the dyno yeterday @ V&E Rigoli dyno day...boost hit 19.5psi then tapers off to about 17.8psi by redline

so still not holding steady boost, its still dropping almost 2% ish, is this normal behavour for a profec b controlling 2 small turbos?

if i turn the Gain up further, i get mad boost spikes...

gain is at 17%

start boost is at 90 (9 psi)

Edited by SiR_RB

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