BK

The factory ceramic turbos are garbage. They spool slightly better than anything else available but fall over as soon as they reach peak 15psi of boost in the mid range compared to anything else in the real world. Reality = garbage mid to top end output meaning car is actually slower and more underwhelming as you don't drive a GTR in the 2 - 4000rpm range expecting it to be the most awesome thing ever developed. Also Garrett -5 is not original HKS 2530 direct equivalent - close but not the same. HKS 2530 will always make more power than a -5 with better overall power curve which I thought everyone knew by now. These billet wheels into existing housings are also stupid as it ends up being way to much compressor flow for the turbine side to handle as Paul pointed out equalling nugget response. I suggest to stop trying to reinvent the wheel and find this RB26 spool nirvana ideology that doesn't exist. If you must twin turbo I'd sell your heap of shit journal bearing MHI based HKS GTIII-SS turbos and just run ball bearing -7 / -9 Garretts like the rest of the world running half decent low mount twins, or find a set of old HKS 2530s for that extra top end. You'll be happier for it guaranteed 👍 (Until you try a single that is 😄)

Not oil pressure- oil volume. As long as it's not the volume requirement for a journal bearing turbo as they require far less oil volume on a ball bearing cartridge. Read what I posted. The turbos oil volume is regulated by the restriction too. On my HKS GT-SS it was to use a different supplied banjo bolt as the restriction, as in say remove the standard banjo with a 5mm odd hole (stock journal bearing heap of shit) vs one with a smaller (1mm or so) hole for a ball bearing cartridge. If the new -9 are restricted as implied at the chra to the correct size it doesn't matter what oil feed bolt you use as long as it's bigger than the chra oil feed restriction fitting. I've noticed Precision doing exactly this on their ball bearing cartridges to stop muppets getting the oil feed sizing wrong - just use a -4 line to oil turbo feed and it will be correct as the chra fitting has been restricted for you correctly.

The difference in restrictions you're talking about is negligible on a turbo oil feed. I run the original HKS GT-SS which are metal ball bearing -9 equivalent. They came with restricted banjo bolt from memory, not an actual restrictor in the turbo. There was nothing in the turbo chra to limit oil flow. The newer -9 sounds like the oil restrictor feed is in the chra for exactly the reason of not needing any restrictors in the fittings or line, so you can't stuff it up.

Put your factory cams back in. Just gonna be laggier with those Tomei lumps.

Genuinely trying to make you understand how it works. Have a look at results for the Precision 5558 or 5858 on an RB20 to see if they are to your liking - they are out there

Why are you assuming an rpm top out at 7500 on a non RB20 engine ? Since this is centred around the RB20 now what turbo do you think is realistically going to achieve this on an RB20 ? Be honest - what do you have in mind for a turbo to have a 4500 - 9000 power band on an RB20 now ? What range is good power to you ? As suggested above have a good read of the RB20 dyno thread to gauge your expectations vs reality. The thread is still completely relevant as the RB20 is still and RB20 engine. You see why most are not revving their arses of to 9000rpm - because of the fundamental principle I raised about the turbo dictating the rpm range, and most of the turbos they're using are falling off power below 8000rpm. If you've gotta go a turbo that is capable of still making power at 9000rpm on an RB20 you have just shifted your whole powerband to the right haven't you ?, meaning you don't have that 4500 - 9000rpm power band you're after. Turbos have definitely improved since then granted, so being the RB20 what it is an ideal turbo would have to spool relatively quickly with relatively low exhaust gas flow but not choke at the rpm you're talking about. An EFR or Precision would have to be the considerations I would think to even have a shot at achieving what you're after on a 20, butI suspect the results will still be underwhelming.

Good wide power band and RB20 is usually not in the same sentence. Cost wise it'll be better to ditch the RB20 and go for a capacity increase.

Is this a theoretical question or you just want big revs ? If you want big revs - ideally have a very large turbo for your motor in question, large duration camshafts (minimum 272 duration) that come into their own at 8 9,10krpm, a head that is ported to flow hopefully 50% more cfm airflow than the stock casting, adequate seat pressure valve springs that can seat the valve at said rpm and have the lightest reciprocating mass bottom end ensembly that is practical (think titanium conrods with less than 1g weight difference and very light crankshaft with excellent balancing counterweighting etc.) All of this needs to be accounted for as crankshaft load goes up at square, so an upto 10krpm motor can turn to shit very quickly. In practice a stock RB26 rev limit can be 8000rpm- 8500rpm completely unopened, so what do you define as high revs ? I say RBs over 9000rpm is above the norm but actually not that hard to achieve up to 9k. Myself ? I have 8500RPM limits across all our RB26 because that's what the combinations support without falling off power.

The turbo power spread 90% determines the rpm limit - everything else is to support that limit - big camshafts and valvetrain, wild head flow etc. You don't strap a turbo on that starts to fall off at 7krpm and continue to rev to 9k for example. Big revs generally mean big turbo.

Targa / circuit car with a 7675, so an 8 second 150mph + targa / circuit car ? Sounds reasonable

I guess that's why you can't beat the factory hard lines. I was gonna say 200 series too - because if that isn't good enough fabricated hard lines are the only option.

If it makes you feel any better I've only done 1070km on my new engine in 18 months- 120km of that at full 600kw+ tuned. So goes to show you that you can complete your end goal and then be like....what's next ? Sometimes it's better to just get the car on the road without holding yourself up on the minor obsessive / compulsive details to make things perfect, as it doesn't necessarily make you drive the car any more frequently.

Tps has a 3 pin plug on the lead for the actual throttle position to ecu and the other 3 pin with actually only 2 wires pinned in is the throttle closed idle command switch. That balancer is a good one 😄

Yes plug and play- preset parameters varying between the blue and red models.

In Australia absolutely yes, but not sure what it's like over there. In the US they can go the Repco equivalent and buy cans of R134A !

That's right - pressure switch has to be activated or relay won't work.

Crap - A relay works or it doesn't. The contacts are good or they're not. When you say tested out of car, you mean you put 12v on the coil to activate then tested for 0 ohm across contacts right ?

Yeah even the blue one is suposedly a 30 times faster signal transfer from sensing g changes, so it's definitely still an improvement over the existing analogue pendulum sensor.

Me too, they are definitely the cheapest for them at about 2/3 the price. Running the red version in both the blue 32 and 33 - I don't think there was any difference in price at RHD between the blue standard and red race versions. The blue one is just supposed to mimic the factory sensor parameters apparently.

Why not the red one ?

None. The pivot supplied is shortened to accommodate the thicker cast release fork.

That's a big turbo dude, but no doubt it be like warp speed on boost being a 1300hp odd turbo. What sort of power realistically are you targeting ? Sounds like your goal posts for power expectations have moved quite a bit now. I too second the Samsonas band wagon 🙃

Maybe stuffed relay then ? Test the relay external to car first.

You mean it should have dropped rpm, but maybe you just haven't found it yet. Keep trying everywhere like injectors, brake booster, etc. Good luck.

Nearly always comes back to a vacuum leak somewhere.