Boost Control Issue On Rb26 With -7's

[snozzle]

Hello all,

Got my gtr tuned 2 days ago but i noticed that its actually very rarily running 1.2bar which i asked the tuner to set it to.

It initially hits 1.2bar, car makes a maximum of 275kw at 4800rpm which suprised me but then plataues off and bleeds off down to 1.0bar. I was expecting max power at around 6000rpm? Im sure if i got the boost to hold at 1.2bar it should make 300kw at 6000rpm.

Anywho, its running a pfc, profec b spec 2, -7 turbos, stock airbox with k&n panel filter, stock afms, stock injectors, tomei pumps and full 3.5" exhaust, rest is stock standard.

My injectors dont seem to be going over 94% atm but i do realise that if i am holding 1.2bar till redline i will need an injector upgrade to be on the safe side of things but i want to know what the best way of going about the boost control problem?

Will a pair of twin pods help or is my ebc just not setup correctly? im hoping my ebc can do the job if its setup differently.. the solenoid is currently in the spot where the stock solenoid used to be.

thanks in advance

[R.3.2.G.T.R]

It's better to have your boost solenoid closer to the actuators rather than other side od the engine, I assume u have experimented with gain settings

what actuators u running?

[paulR32gtr]

I don't have a boost controller at all - 1 bar HKS actuators that come with GT-SS's, or Garrett make an equivalent, hook up to the standard solenoid pipeing / hoses just run a little air bleed hole back over where the stock solenoid is to up the boost as desired. Has a perfect boost curve ~16/17psi.

I know it sounds really ghetto but believe me you will waste half your life trying to get an EBC to do exactly what you want.

Saying that- BWRGTR is right - try running your EBC as close to the actuators as possible and then tinker tinker tinker.

[snozzle]

sigh, i left that part of the ebc install to the tuner thinking they know better than i do >.<

i havent played around with the ebc settings coz if i manage to get it to run 1.2bar to redline im sure it will lean out..

will pod filters help my case or is it mainly an ebc/solenoid position issue?

im running the standard actuators that come with the turbos when you buy them off garrett, ill have some pictures up tonight

thanks for all the input so far guys, ill search up for some diagrams of ebc setups that have been proven to work

[SimonR32]

upload a dyno graph!

[paulR32gtr]

Yeah definitely better doing it while monitoring AFR's especially up around the 300rwkw mark with stock injectors and afms.

Did you have a chat with the tuner about it?

[JonnoHR31]

write down all the settings in the profec so you can set it back anytime. then try running a little more gain, keeping an eye on inj duty obviously.

if your not sure how to use the profec i can probably help you out if your local

[snozzle]

Ive been really busy with work lately but ive managed to find this thread; http://www.skylinesaustralia.com/forums/Si...;hl=rb26+profec

ive booked the car back in for a retune on wednesday so ill change the solenoid setup before then and let the tuner have another go and controlling the boost curve

i should bolt on some filters while im there too i think! ill try post up a dyno graph tonight and another one next week when shes tuned again

[snozzle]

[NSNPWR]

Add a boost curve to the next graph

[snozzle]

ahh silly me, upon reading the graph again with more attention to detail, it looks like im actually making 275kw at 6200rpm haha, max torque is at 4700 , yeah ill ask tuner to include afrs/boost on next dyno graph if possible

[SimonR32]

graph looks fine... sean is a great tuner, doubt there is a need to get it back on the dyno

[JonnoHR31]

looks like you get a small spike in boost then it drops off fairly quickly. either your set boost or gain in too high and your set isnt high enough if you want 1.2bar

[SimonR32]

  JonnoHR31 said:

looks like you get a small spike in boost then it drops off fairly quickly. either your set boost or gain in too high and your set isnt high enough if you want 1.2bar

You're looking at torque not boost...

[JonnoHR31]

i know what it is....

like i said, it looks like your getting a small spike in boost

[snozzle]

Ok so i made an attempt to shift the solenoid to the other side but found that the metal actuator line that bolts into an adaptor with a 12mm fitting, above of the rear turbo, was completely loose!

I bolted that in, made the lines to and from the solenoid roughly 20cm shorter and thought id just give that a go. Couldnt be bothered taking off the intake piping etc.

Ive tried using a lower set gain value but a higher gain value and it has actually reduced the spiking and is now holding a stable 0.9 bar on the low boost setting, before it was spiking to 1.0bar for a split second then holding at 0.8bar.

I havent fiddled with the high setting yet, car is going in for a retune 2moro as ive been getting some high knock readings come through at high rpm on the hi setting >.<

[Rolls]

With those power levels you really want to be doing those adjustments on a dyno as you can't tell if its leaning out or if you are maxing out the injectors.

Perhaps ask to stick around when he does it so you can have a play as well?

[JonnoHR31]

he adjusted the low boost. it will not be maxxing injectors or going lean if it was tuned properly

[snozzle]

the dyno was occupied when i got there so sean plugged up the laptop to my car and we went for a drive, vin diesel paul walker styles, without changing any settings there was no more knock readings no matter wat i gave to it! sean rekons the knock wires were getting interference near the ecu so he put some insulation on it and tucked it away

as for the boost control im gonna leave it for now, im quite happy with the power as it is anyway, when i get some money for injectors and cam gears ill then worry about it wen it goes back on the dyno

thanks for all the input guys