Jump to content
SAU Community

Recommended Posts

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?

Link to comment
https://www.sau.com.au/forums/topic/170564-boost-level-and-apexi-avcr/
Share on other sites

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.

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.

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.

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?

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?

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 :P

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 :P

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

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.

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.

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.

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.

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?

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? :P

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Had a go at the stuck crush tube this afternoon. Tried things like grips and a chain wrench first but wouldn't just twist straight off. So got to work with a drill. Started small and kept a depth stop on to make sure I didn't drill into the bolt. Made a line of drill holes all the way up and enlarged them. Then a combination of chisel and Dremel to split it all the way up. Levered the split to get oil in there and eventually it gave a bit while levering. Worked it back and forth with loads more oil till it was spinning freely, then with grips I could work it downwards and off. And no significant damage to the bolt (not by me anyway - just the 27 years of rust)
    • Well, I'm tired. I'm tired because about 4PM yesterday, before today's appointment someone immediately bought my bumper. They couldn't get it any other day as they're on the way back to NSW. So I had to do that big GTR conversion I had been planning. Unfortunately, the information on SAU about what you need and how this is done is incomplete. So what should be a simple bolt on affair, yeah, it's not. Did you know if you use all GTR items the bonnet won't close? This little manuever sent me into about 1am the night before trying to dodge a way to get it closed. I will have to revisit this in the next few days  - or maybe not, I may let a body shop figure it out. It all needs to come up and my motivation to pull the bumper off is low. It also seems to hit things in the bay where the GTT bonnet didn't. Yes I used 100% new OEM GTR items. Today, I had the joy of driving to the dyno looking like this: Given I had roughed in the fuel and given sensible but pretty conservative timing, I didn't really bet on having the car drive out any real difference than when it drove in. Sadly due to a miscommunication and laptop fun and games (and almost bricking the dongle, prayers and firmware updates indeed), I ended up using HP Tuner credits to licence the car that was already licenced. So in the end my laptop was used. It turns out my butt dyno is still well calibrated after all this time. The 325kw was on 74% Ethanol, the 313kw line was on 98. The other line is the 'before' line which was 281kw. While the numbers are pretty low, they're pretty in line with what you'd expect. Even if US dynos bump the whole result up about 50KW, gaining 10-15% is similar gains.  The curve of the cam is pretty much spot on with what was discussed as well. All this said, it still feels bad to not see the number you secretly want to see. Even if the car drove great beforehand, and I knew pretty confidently the car would drive out much the same way it drove in due to the nature of a wellish dialled in LS1 not gaining much if anything at all from being tuned from where it was. As expected, the car isn't particularly sensitive to running it at anywhere between 12.0 and 13.0 - And the initial timing at 20deg and 12.0 made 308KW. So 3 degrees of timing, and leaning it out to 12.7 for 5kw, anything above stopped giving any benefit until E85 (which has an additional 2 deg as before). Car itself behaved entirely fine. I found out that 100C = 1.15V! IAT at about 7pm was 19C. I might mess with the bonnet mounting.. but given the REO NEEDS TO BE CHOPPED TO FIT A GTR BAR this is possibly something I may leave gathering (more) dust until it returns to paint jail.
    • It sounds farrrrrrr too cold at your place Duncan... Here I was thinking our 10 degrees overnight is getting cold...
    • oh yeah, reminded this morning....bin lids frozen shut too
    • In my case not, because of total reno. But yeah.
×
×
  • Create New...