Boost Level And Apexi Avcr

[Crans]

Reciently purchase an r32 gtst.

Has the following mods that I know of when i bought it.

FMIC

Pod filter

CAI

Apexi AVCR

boosted to a tad over 11psi or 0.83 kg/cm2

been reading the avcr manual and i turned the controller off.

Went for a drive and its still boosting to the same level.

Turned the controller back on and upped the settings and it boosted to 13psi proving the controller is working.

Would i be correct in saying that the current mods raised the boost to 11psi without needing to touch the turbo?

[Birnie]

Your acuator is set to 10psi so you're not far off that.

If you want to have a fiddle, get another piece of vacuum pipe and run it from the inlet piping straight to the actuator with not solenoid in between.

Have another run and see what you get.

That way you can tell what the 10psi actuator is giving you, without any disruption of airflow to it via the (even if off) boost solenoid.

[Crans]

What boost is the rb20 set to as stock? i thought it was around 8psi?

I dont think the turbo has been touched

[BAMR33]

The boost solenoid on the avc-r doesn't activate until 30% duty cycle, so previously when you were running 11psi the avc-r wasn't doing anything.

Generally in boosted cars when you free up the intake and exhaust you gain a couple psi, nothing to out of the different.

[Birnie]

Nope, RB25 is 5psi standard with a boost solenoid that goes to 7psi.

RB20 is definatly 10psi standard.

I have one now on my upgraded turbo and it held 10psi exactly without a boost controller. Straight vacuum pipe from intake pressure to wastegate.

[Birnie]

Generally in boosted cars when you free up the intake and exhaust you gain a couple psi, nothing to out of the different.

I know that's what most people think but i still have my doubts.

I believe that the mods will allow a high amount of air to flow with less restiction but if the wastgate sees over 10psi, it will open it up until it settles back on 10psi.

I have a full 3inch zorst/pod/FMIC/POwer FC/HKS2535.

When i swapped from standard turbo to the HKS2535 with an RB20 actuator, my boost gauge showed exactly 10psi when no boost controller was installed.

How can it not when it's designed to open above that?

[Roy]

From memroy (4 yrs ago) i use to get 0.85 bar with my AVCR turned off. HKS exhaust, filter and intercooler sees the engien naturally breathing better and running 12psi as was my case.

[Birnie]

Ok, interesting.

I hit 10psi with a straight thru vacuum pipe.

I know have the PowerFC boost kit so same solenoid.

I'll turn mine off tonight on the way home and see what i get.

It may be causing some sort of restriction even when off casuing the wastgate to miss out on some pressure, causing the boost to go up.

Roy, are you talking about an RB20 actuator in your case?

[ricsvtr]

Yeah I agree with Birnie, I have a 3inch turbo back exhaust and pod filter on my R33 and my turbo still only boosts to 7psi.

[Roy]

R33s and R32s have completely difference means of controlling boost, and use different actuators. The example i used a few posts ago was when i had a std turbo on my car. I had it for 4 years with the std turbo. Firstly with a cat back and filter. Then cat back, filter and IC. With the IC isntalled i was getting 0.85bar with the AVC-R turned off. I woudl set it to 0.85 in setting A to try and get it to boost harder (maybe there was a difference) and Setting B i used to run 0.95bar or 1.0bar. Std RB20 turbos arent as fragile as some of the later model crap Nissan put on the R33 and R34

[Birnie]

R33s and R32s have completely difference means of controlling boost, and use different actuators. The example i used a few posts ago was when i had a std turbo on my car. I had it for 4 years with the std turbo. Firstly with a cat back and filter. Then cat back, filter and IC. With the IC isntalled i was getting 0.85bar with the AVC-R turned off. I woudl set it to 0.85 in setting A to try and get it to boost harder (maybe there was a difference) and Setting B i used to run 0.95bar or 1.0bar. Std RB20 turbos arent as fragile as some of the later model crap Nissan put on the R33 and R34

Can you please specifiy what car you're talking about. I'm still not sure but with 12psi with no controller I'm guessing RB20

R33/32 both control boost with wastgate actuators, doesn't every car? (or external wastgates)

Just that the actuators are set at different levels, 5psi-R33 and 10psi-R32, and the R33 uses a boost solenoid to get to 7psi.

What are the completely different means you are talking about?

I;m guessing that even thought the AVCR is off, it must be fiddling with the wastegate pressure reading to get you to 12psi.

I still don't see how mods make you gain 2psi

[BAMR33]

The actuator signal from the r33 is taken after the intercooler where the air is denser, this is the true pressure reading. The r32 takes the signal directly from the compressor housing, this is not a true pressure reading as it's not the pressure at which the air is entering the engine.

[Roy]

Ok. You are right, they all use a wastegate/actuator of some sort. Only R33s sample boost pressure after the intercooler. They have a softer spring in their actuator so run less boost.

The R32 samples its boost signal from the compressor cover of the turbo. So the harder actuator spring opens when the pressure in the compressor makes it open.

So, whether it is a 10psi spring or not, i have no idea. Sounds like it could be close. But the thing to remember is if you are running a boost gaugge you are plumbing it into lines on the manifold. So on the R32 the wastegate will open whenever the pressure on the outlet of the compessor cover dictates it. If you put a crappy IC (std) on the car then the inlet manifold wont see the same pressure at the compressor cover because of the pressure drop. So putting a better flwing IC on your car, the actuator and wastegate open at the same time, (give or take) but now your engine is actually seeing the boost that the turbo is generating.

Thats why it makes no sense to me when ppl say the std cooler is good for xxxxrwkws. In a std R32 gTSt it is costing you boost and power.

So to clarify. With no ebc at all. My car happily ran 11-12psi (depending on weather) measured from a t-piece that supplies its signal to the std map sensor used by the dash. So when ppl say 10psi, im guessing thats measured at the inlet manifold on a car with a std intercooler.

[BAMR33]

The small stock intercooler of the r32 also ads back pressure, which raises the boost pressure between the compressor and the intercooler. This pressure is measured by the wastegate but not by the boost gauge further upstream where there is no restriction i.e straight into the intake manifold.

[Birnie]

Yeah, I'm seeing 10psi from the manifold reading on an R33 using an RB20 actuator and Hybrid FMIC

[Birnie]

.....and thanks for all that info Roy.

I'm only familiar with the R33 and had no idea about those differences..Thanks

[Crans]

Thanks guys really imformative i no longer thing something is broken

So what boost can i run it up to? any one got a guide to tuning the AVCR?

[BAMR33]

Just adjust the solenoid duty cycle up bit by bit until you get your desired boost level. From memory go to settings choose setting [a] and then adjust from there not too difficult. Don't worry about gear based learning or anything like that until you get your car on the rollers for a tune.

[Crans]

From when i had a play adjusting the duty didnt do a thing. adjusting the boost made it go up higher but i wasnt keen on playing with it until i knew exactly how much boost the stock turbo can handle.

Are there any tricks to bring boost on quicker or do i just pump it all up to the desired level and adjust from there is theres any spike?

[Hardman69]

From when i had a play adjusting the duty didnt do a thing. adjusting the boost made it go up higher but i wasnt keen on playing with it until i knew exactly how much boost the stock turbo can handle.

Are there any tricks to bring boost on quicker or do i just pump it all up to the desired level and adjust from there is theres any spike?

Did You get a manual with your AVC-R ? Read it. It tells U all U need to know, just not very clearly !

The boost value You set in it is the "Target boost" that it'll self-learn the solenoid Duty-cycle for. The feedback rate You set in the options menu affects how quickly it adjusts to the correct duty cycle for holding this boost level. The Solenoid % U set is the "Start duty" which is what the AVCR jumps to when "boost control starts" at about 0.3bar.

Play with it, learn what it does, get a feel for how aggressively U wanna bring the boost on. Note that too high on the feedback rate will cause boost fluctuation, as the AVCR over-compensates all the time. I'd say set feedback around 8 in first, 7 in 2nd, 6 in 3rd etc.. . . 5th gear U want fairly calm response, so 3 or 4 is fiiiine. Like the manual says, if U set the start-duty a bit high, boost will come on quicker, but it will spike slightly over the set boost, until the AVCR self-learn can stabilise it.

Dig?