Lithium

Thats very tough What numbers did it put down in the end? When is this bad boy going to be making its debut?

Yep agreed, a bit annoyed as the AVC-R was supposed to be a flash wee piece of equipment.

Well I got someone to drive the car for me and take vid, I have been trying to set it up to target ~1.1bar - so far the tune we have got in there is very conservative, basically so I can suss boost control out enough that a dyno session would be justified without popping the motor so its not going to be making the best use of the air its getting at the moment. Either way, this should give a rough idea of the spool now I've had a tinker with the AVC-R and boost relief valve. I have a mate driving, basically gave it a stomp from around 2900rpm in second which was where it was previously at its worst: http://www.youtube.com/watch?v=-AYS8ixmMPY I suppose I should add as I don't know what other peoples .82a/r GT3076Rs are like on their RB25s - but this is much much better than I was getting before, and my mate wasn't giving it 100% throttle (don't know if or how much difference that'd make). It isn't PERFECT but I consider the boost relief valve experiment a success, considering the money spent vs. gains had. If there is a better solution for the same or less money, I am still keen to hear but this is definitely keeping me a fair bit happier.

Yep, just went for a thrash and I really need a passenger to help me keep an eye on it - it builds boost good and quick but I can't tell if it holds flat or not Its a bit too quick to safely watch that, and it feels good but I don't think its quite perfect yet. I need a passenger to keep an eye on or film things.

Good luck with, would be good to see

What you said above is not disagreeing with my post - a GT3076R is FINE for 400rwhp, and as you said above its not the easiest thing to do on an RB20. Thats not because of the RB20 + GT3076R combination, its because of the RB20 part of it. You have to spend the money to make an RB20 making >400whp, or push it that hard. GT3076Rs are making >400whp left right and centre on better motors - you could upgrade to an RB25 when you change your turbo then the 400whp will be easy

I had some fun during a gap in the weather today, so here is the new pressure relief valve I got from Norgren: I took advantage of the opportunity of doing these changes under the supervision of Tomei: I did my first tests with the twin port wastegate as I need to remodify the setup to suit the old wastegate (changes were needed for the twin port) as my relief valve is best suited to a single port actuator... and the dual port actuator seems to be rated to 7psi vs my old actuator's 12psi. As a result of this I had some boost level oscillation, but that was no surprise. My flatmate is going to reweld up my old actuator setup so I can re-install that - and going by tonights testing I suspect its going to finally have the type of boost control I have been hoping for: I was a little weary of it potentially boost spiking, but no issue with that at all - with the soft spring it hits 1bar and drops back a couple psi and then rebuilds it in reducing swings but I expect the harder spring and a bit of tuning to sort it out.

I could be wrong, but I thought my actuator indirectly came from GCG - it was sent to me from someone in Australia

Yeah sorry I was a little short, posted on a few forums and had a head of people telling me to do things I had already tried and mentioned haha. Fingers crossed that trick does something useful, if it is it could be handy for others looking at similar solutions. I will post the result either way when I get the valve

For what its worth, a guy in my area put a 56Trim GT30R on his 4WD Neo RB25 Stagea and is making 270awkw at 17psi with it and absolutely loves it. Its making 17psi by around 3700rpm and can lose all wheel traction giving it a boot full, by all accounts its a heap of fun for a bus.

Yeah I have asked a couple of times in this thread if anyone can point me to a supplier of reasonable priced actuators suited to the application - so far in NZ the cheapest I have found for one is ~$470NZ which is far too much for me at this stage. The actuator/AVCR can hold 15psi or 17psi flat once it reaches it so I can't see any reason why it should be technically impossible to make it reach it quicker when the engine is clearly capable of doing so... I will post results of how Mondays experiment goes when I do it, seems no one seems to have tried it.

Nah you are in the right direction, the problem in this case seems that the actuator is so soft that as soon as it gets a blast of >10psi it opens even if it has been bled a bit by the solenoid. The AVCR doesn't allow 100% duty so unfortunately I can never completely block the actuator from opening... which is why I have decided on a pressure relief valve to completely block pressure from the actuator until around 14psi and THEN let the AVCR take over

Someone on another forum asked how I had plumbed up the whole thing, so I thought I better show it here: I have ordered a Norgren pressure relief valve which will be here on Monday, will see what happens if I just block the pressure feed until 1bar is reached and then let the AVCR regulate it from there - given it seems to hold the boost when it is finally reached.

I do have an internal wastegate, its just dual port like externals

Haha not sure if you are joking or not - but just in case, I was free boosting. I backed off when boost hit 1.1bar - not when it stopped climbing. It was climbing FAST, and if I didn't lift off it would have kept going until something else stopped it It was just a test to see if it will spool well if the wastegate doesn't open prematurely, and it does. Fastrotor - Not sure quite what you meant, do you understand how an electronic boost controller controls a dual port/external wastegate? I'm a little tired, so could just be failing at reading you right. The dual port actuator has two sides, one is the "compressor" feed which is just a line from a boost source - same as any other turbo setup without a boost controller. The other goes to a second port on the wastegate, which is used by electronic boost controllers to regulate boost. What they do in this case is let boost into that side of the wastegate to effectively beef up the actuators resistance to opening by pushing the wastegate closed - when the target boost level is reached the boost controller stops pushing boost into this side of the actuator and the the "normal" spring tension collapses to the original boost feed and wastegate opens. What I did to prove the actuator would allow this to happen is just put the boost feed into both sides of the actuator, to ensure that it stayed shut- just in case somehow it could creep open... which would be possibly caused by a leak or restriction on the boost controller line. If I am answering the right thing, does that make sense?

Yeah, thats one of the things I was trying to rule out.. to add to it, I did a test which cheated a bit less than the above. I removed the AVC-R from the mix, and just plumbed the pressure source directly into the "boost controller" port of the internal gate as well as having the pressure source fed into the "compressor" port on the wastegate. Took it for a drive and again 15psi by 3600rpm, so the wastegate is working exactly as it should if the boost controller was letting pressure through to the boost control port of the wastegate while spooling. Thats what I hoped as well

I am thinking that might be the way to go - are there any dealers on here who would be a good one for me to speak to about sending one to NZ? The support for that kind of thing here is terrible. Skylinecouple, cheers - yeah the car is running fine... I was fighting with the issue (I think I mentioned it to you) way back when, but while improving it a little nothing has fixed it completely and previously hasn't been annoying enough for me to really attack with everything but now the novelty is wearing off and I want it to go as good as it should be! In the meantime, I am off to see if I can find someone who supplies Norgren bits for me to play with haha

I hadn't but just had a hunt around and found it, dammit I wish I found that before I bought my AVC-R It was actually vs the PFC boost control, but presumably the same thing.

What do you mean by size? Seems to open around 12psi... Here is what the turbine housing/wastegate flapper look like:

One of the reasons threads like this can go in circles, or seem like people are missing things is when people don't read the original posters posts clearly - you obviously missed the 800x600 image of the Apexi AVC-R EBC I have been using to fight this issue I have been almost tempted to get a ball valve to put on the feed to the AVC-R/actuator... though I really don't think I should have to consider that. Oh yep, that makes sense - creep hasn't been an issue, its just the bringing boost up at the start which is and I have my preload maxed out

Enlarged wastegate hole helped spool? I would have thought it would only help fight creep? I actually have a "big flap" internally gated housing - its not a tiny one.

Oh right - so your GT2871R behaved like I am describing and was actually resolved in the end with preload? OK I will max out the preload tomorrow and take it for a drive. The other thing I have considered is using the "Norgren" boost control setup Autospeed wrote up a while ago for their Audi, if anyone has any thoughts on it?

I have almost maxed it out, it stopped really returning noticeable gains (was opening at 6 initially!) after a while but ok.

Hi guys, I'm bound to have spoken to some of you about this issue I have been fighting for a while but now I feel compelled to try and really get it nutted out, the lack of lower-midrange torque is starting to frustrate. Anyway, the short of it is that my internally gated GT3076R (yeah yeah I know...) opens starts to open wastegate before it reaches the desired boost level - which induces a reasonable amount of lag any time I step on the throttle. Here is the best way I can demonstrate how it behaves when I am targetting 15psi: Obviously I would much prefer it to hit and hold 15psi instead of pissing around from 11psi to 15psi. I have tried an AVC-R and a bleed valve as different kinds of boost control which help SLIGHTLY but definitely don't fix it, and I am currently trialling a dual-port actuator which so far does the exact same thing. Today I decided that to rule out the possibility that the reason it spools lazily is a boost leak or some other issue elsewhere, I'd do a quick run to 3500rpm with the actuator hose removed to see how much it builds and my result is: So clearly the turbo and setup is capable of building 1+bar well before the 5000ish rpm I am stuck with at the moment, but the trick is making it do so without free boosting. Any one have any ideas? It may help reduce some stress here Cheers!

Its worth looking into the Garrett non-ball bearing turbos too - they are rebuildable quite cheaply and probably competitive with the Masterpower turbos If I were looking at saving dollars I'd go a Holset.