26 Boost Control Issues

[Parker]

Hi,

I am experiencing some very frustrating boost control problems on my 32 GTR. When purchased the car had an old model Blitz SBC type S that was hopeless for controlling anything over 12psi on my car. I did a little research and found only good things said about the Blitz dual SBC type R (dual solenoid one) and went out and got one.

On the initial dyno session the spark was getting blown out by boost because of the poor condition of the plugs. Platinum ones gapped to 0.8mm went in and fixed that problem. On the dyno when the boost gain is turned up boost will fluctuate -+1 psi after reaching the set value (it shows a nice little wave on the dyno read out). When the gain is turned down the boost curve can be flattened out somewhat but it is nowhere near rock steady. Now it will reach the set value and drop a little rise back up to the set value and fall again. It looks very much like the frequency of the boost fluctuation wave has just been reduced (i.e. just one fluctuation now instead of about 5 with a higher gain).

The car is a 32 GTR with 34 N1 turbos(bought new), Djetro PFC, built internals, 700cc injectors, 044 fuel pump, full exhaust etc. We are currently running 17psi and getting 362hp rwhp but it is really evident that the unstable boost is killing the power from about 5,500rpm onwards.

To say that this isn't what i expected from one of the 'higher' end of the EBC range is a bit of an understatement. Does anyone have any ideas on why this is occuring and what to do to go about fixing it?

Cheers,

Ryan.

[itbmils]

Hey Ryan

I also have an R32 with similar mods - if you look in the dyno results thread you should see exactly what I have

I run my R34 N1s @ 1.2 bar (18psi) and see a solid 401hp @ the treads

I use a std PFC with the Apexi EBC - and it works fine. I do get some fluctuation - but I don't think it's as much as you are seeing (shrugs)

I currently still have the std injectors - and I know that once I swap them out for larger units, I should see even more power (my current tune is limited by the 100% duty cycle warning I keep getting from the PFC )

HtH

Scott

[Parker]

Yeah that's the frustrating issue Scott. The package has so much more in it and i'm not being able to get to see it because of continued boost dilemas. It's really frustrating.

Power rises smooth and fast with the boost but once boost peaks and drops everything flattens off when i should be seeing results closer to what you have.

I find it hard to believe that this is just a case of this boost controller not working for me on this package when i know it works fantastically in other applications.

[Parker]

Does anyone have some advice out there?

I've had a closer look at the dyno chart and been more observant of the boost since posting and can add more hints to you mechanical geniuses out there.

Boost rises rapidly and smoothly to 19psi, drops to 17psi, spikes to 17.5psi then drops back to 17psi by redline.

I've just installed splitfire coils and peak boost has raised by 0.10Bar with no changes to engine management or boost. (boost fluctuations are still present)

Is the problem with:

a) the boost controller

b) boost controller set up/settings/install (doubtful on this one as i trust my tuner)

c) stock wastegate actuators

d) something else

Has anyone else experienced similar problems with this boost controller or with their GTR's?

Cheers,

Ryan.

[Amaru]

Try upgrading your wastegate actuators. I believe the stock ones open at around 7psi of boost pressure, so your boost controller solenoid will be working overtime trying to hold stable boost.

Boost controllers were never designed to vary the levels so much, and you should try and run an actuator opening pressure as close to the target boost you want as possible.

I had a similar problem running stock actuators and running 22psi with an AVC-R. Upgraded to HKS actuators with an opening pressure of 18psi and it worked brilliantly.

[Parker]

I have been told that N1 actuators aren't the best items for boost control but it seems many others using these units aren't having troubles judging by the power being made in the RB26 turbo's thread.

[ferni]

As already mentioned, try to get some actuators set closer to the boost you want to run, the closer they are, the less work your EBC has to do....

[SDEWY5]

Just another question loosely related to this topic, i have a Greddy ProFec B-Spec 2 boost controller and i am having trouble with boost spikes occurring, i have gain on minimum(5%) and the solenoild is set at 25% and i am getting a very accurate 10psi, but if i am at high revs and hit it (ie: 5500rpm) boost will spike up to approxiumately 13.5psi.

Should this be expected or have i done something wrong? running hybrid turbo with standard computer probably has something to do with it..