Rb26 Gt-ss Turbos - When Should Boost Kick In?

[Blitz]

Yeah there is something definitely wrong there, my GT-SS's come on strong from 3000rpm in the higher gears and around 3500rpm in first from memory. They feel a bit laggy between long gear changes, but if your quick it is full power the whole time!

I just love them for that reason, you put your foot down and your away. Response wise, i was next to a new wrx sti the other day, and off a slow rolling start, i came on boost only a fraction of a second after he did.

Bingo - while cruising at moderate revs, I only need to touch the gas and I have 20psi in a heartbeat

[justinfox]

PS: Thanks so much for the input Paul. Coming from you (and Jim) and the stuff that Indy told me today about the AVCR, that makes a lot of sense and seems like a direction worth stepping in.

[Blitz]

Good luck with it Justin, im sure your car will feel like a whole new beast once this is sorted.

[wrxhoon]

Well set up GTSS's will be on full song bellow 4000 rpm on a well built or stock engine. If you have lower compession ratio you will find they will boost later though . I would imagine you will have stock comp 8.5-1, then you should have full boost under load well before 4000 rpm.

If you think it could be the boost controller why not disconect it and use the actuators , set them up to say 1 bar then take it for a spin and see where you get full boost. If you are going to run 1.2 bar boost you should have the actuators at least 1 bar or a bit above .

GTSS turbos spool up almost like the stock R34 turbos ..

[godzl1975]

Your kidding right?

trust 618z's tho

[R31Nismoid]

But Ash, i cantr be the only guy that was running an 8psi spring pressure and with a bit of adjustment and self learning on the track it held 18psi no problem. Thats a 10psi increase over the spring pressure and it worked fine.

So again, if someone is having trouble with theirs and cant get it to work, i will buy it as mine died in the last fire, and im cheap and cant bring myself to pay new EBC prices when the setup i have now works fine, only it isnt adjustable in the cabin

your running a single line to one larger external gate.

Its a lot different to a twin internally gated setup that puts demands onto things.

Your talking apples and oranges. Yes they are fruits, but not the same

[Gav]

your running a single line to one larger external gate.

Its a lot different to a twin internally gated setup that puts demands onto things.

Your talking apples and oranges. Yes they are fruits, but not the same

It's not often that I agree with R32Nismoid, but he's right on this one. I was never able to get stable boost on my large internally gated terbs (GT-RS) with the old AVCR fitted.

By going to a dual solenoid unit I was able to get a much steeper boost raise without spiking (i.e. wastegates are kept absolutely closed until desired boost is hit and then controlled to give a very stable boost).

As previously recommended, try a manual boost controller or even direct off the actuator springs. I think the HKS kits come with 1 bar actuators from memory?

[justinfox]

I did a little research last night on GT-R's in hyper rev magazine (GT-R's built by Japanese performance shops, eg: Mines GT-R, Top Secret GT-R etc). Not one single GT-R featured in the entire magazine runs an AVCR. It was split pretty even between the Blitz boost controller and the HKS one. Interesting...

I've booked in with Brad from Westside to remove my cat next week, which was installed at High-Tech mufflers (but not by Lambros), it's a high flow, but they really had to cut it up to get it to fit and it could potentially be a weak link as the exhaust is new, headers, all other pipes are new. After that I'll look into the AVCR.

Again, thanks guys. Heaps of help!

[DAN00H]

Cam timing is out - I reckon the AVCR is not the issue.... Justin, get your tuner/ builder to recheck the timing and belt positioning...

[Blitz]

trust 618z's tho

Not really relevant to this thread then is it

[PhilGTR]

Does anyone use a Greddy profec b spec 2? I had a look at my gain setting and its at 15%, is this a normal setting or is this really low?

[Blitz]

Does anyone use a Greddy profec b spec 2? I had a look at my gain setting and its at 15%, is this a normal setting or is this really low?

I will ask Sewid to post in this thread, he runs GT-SS's and a Profec B Spec II

[ferni]

The AVC-R just doesnt keep it going well enough is what it seems, regardless of "how well" you set it up, its simply not the best tool for your money.

On a mild turbo, with ~15psi, no worries. AVC-R isnt too shabby, but if you asking a lot of the setup, you'll be disappointed time and time again.

If people want to spend lots of $$$ trying to get it close to acecptable, thats thier choice. Im just pointing out that there is an easier way to do it.

ferni had to change controller aswell because he was having issues... cant remember what he did have but i suspect it was the avc-r.

It just didnt do the job well enough. It worked, yeah, but there is better stuff out there for the same/cheaper price.

Nope i had no boost controller, i was told to buy the blitz spec R so i did.... works fine for me.

i'm with wrxhoon - wind up your actuators to say 1 or 1.1bar, disconnect your boost controller and try it, see if its better, but yes you should be hitting boost much sooner... the gtss's make my car almost feel like a 3 or 3.5litre they are that responsive....

Also your AFR's look a bit average, especially early in the rev range.....

good luck.

[Roy]

Fair point Ash...Justin, sell me your AVCR. I like them

[Munna1]

Well set up GTSS's will be on full song bellow 4000 rpm on a well built or stock engine. If you have lower compession ratio you will find they will boost later though . I would imagine you will have stock comp 8.5-1, then you should have full boost under load well before 4000 rpm.

If you think it could be the boost controller why not disconect it and use the actuators , set them up to say 1 bar then take it for a spin and see where you get full boost. If you are going to run 1.2 bar boost you should have the actuators at least 1 bar or a bit above .

GTSS turbos spool up almost like the stock R34 turbos ..

Great point wrxhoon, disconect that sucker and see what happens.

[Swiper the Fox]

PS: Thanks so much for the input Paul. Coming from you (and Jim) and the stuff that Indy told me today about the AVCR, that makes a lot of sense and seems like a direction worth stepping in.

No probs Justin, the avc-r is a good middle of the road boost controller for mild road application and has to be set up correctly for optimal function. Simply put its too smart for its own good....you don't hire an accountant to flip burgers do you?

Disclaimer: the information given in this post could be and possibly is total bullsh1t.

[frankxinyu]

Does anyone use a Greddy profec b spec 2? I had a look at my gain setting and its at 15%, is this a normal setting or is this really low?

in regard to profec B spec II, how good is it? what kind of boost can it run?? it is still a single solenoid unit, isnt it?

[pnblight]

justin i don't believe your main problem is in boost control, I can quiet safety say that you have got big problems. Unfortunately there are many issues that contribute to boost responce

compression ratio

cam timing (very big)

exhaust design

induction system design

this is a dyno sheet of a rb26 with the bigger gt2860r turbos

www.hyperdrivems.com.au/images/dyno/peterblight.jpg

so best responce is possible and i would be looking at the cam timing (both exhaust and inlet) and restriction on intake and exhaust systems.

pete

ps hope it helps best of luck

[izataskyrine?]

AVCR settings, no idea. Power FC ecu.

Blitz - CRD would for sure sort it out. I totally agree. Looks like I have to find a tuner and forget the "warranty".

lol warranty... lol

mate i have a friend with a 32gtr with standard internals and 2530's not 100% sure how they compare but he is spooling up at about this kind of rev range so with all that internal work cams pfc, avcr etc this should be on by about 3500??

gl with it sounds like it will be an animal eventually

[sewid]

Does anyone use a Greddy profec b spec 2? I had a look at my gain setting and its at 15%, is this a normal setting or is this really low?

Yeah I use that boost controller and it does a job.... I am looking at changing it though as it does not respond as well as I'd hoped to fast changes in boost.

15% gain is actually too high for me... im using 9 or 10% maybe 12... I'm trying to keep the spiking capped as it gets me worried.