bradsm87

U wouldn't want to run more than about 15psi through the .63 because that's when the backpressure goes a little crazy and heat becomes a problem. U should make 270rwkw on 15 psi anyway so it won't be a problem.

Yep those bottom ones are the new Garrett castings and very good.

I wonder how that guy deals with compressor surge on the big turbo. If the small turbo makes 20psi down really low, there's no way the big turbo could not surge at 20psi when it's not even spooled up yet. Very impressive! Edit: I paused the vid and answered my own question lol. The big turbo is before the small turbo on the inlet side. I wonder what the shaft speed on the smaller turbo would be with all the airflow from the bigger turbo going through it.

ATP advertise that the .82 and 1.06 divided housings are made by Garrett and full race say the castings are a lot better than the .78 GT32 ones.

- Tial MV-R 44mm wastegate with v-band flange welded to factory manifold - Garrett GTX3071R .63 for about 250-290rwkw on low boost or .82 for 290-340rwkw on high boost. The 250-290rwkw option requires less supporting mods so cheaper.

Lol what I've been trying to say is that won't prove anything unless the same person puts ALL of the above turbos on the car and tuned them all. Turbo comparisons mean nothing unless on same car.

they are different cars with different engines, exhausts, intercoolers, intercooler piping lengths, tuners, the list goes on and on. u can't compare turbos using those different setups. HKS turbos are made of Garrett parts so it's very easy to compare them. Also lol at thinking even a GT-SS is better than a Garrett -9. It's exactly the same turbo. EXACTLY. HKS used to have exclusive rights to this turbo but not anymore. No wonder why things move so slowly forwards i. this industry. too many ppl still buy products because they liked how 100 other cars went 5 years ago so buy the same shit when improvements have been made over that time.

Smaller A/R turbine housing doesn't necessarily mean less lag. Some (sometimes all) of the spool incease from quicker pressure build-up is lost in the fact the engine has to work harder agains the higher backpressure. There is no denying whatsoever that the old GT3071R MUST AND DOES make more power than a GT2835. The only thing that's debatable is the lag difference. There is no way the smaller turbine wheel AND smaller housing makes more top end.

The GT2835 practically IS a GT3071R. The GTX3071R is a newer, better version. The GTX3071R also comes with an 0.6 A/R compressor housing too which improves efficiency across the range. Bloody HKS fanboys Next thing U'll be telling me that the GT-SS will outperform the Garrett -9.

One combo that'd definately be an HKS killer would be the GTX3071R with a Garrett divided T3 1.06 turbine housing, twin scroll manifold and twin gates. The 1.06 divided has about the same max flow as a non-divided .82 but quicker onto boost.

lol. not at all. i've only ever bought 1 turbo in my life but i do my research. i really cbf going into it but which rims are lighter? which pistons are generally lighter? forged or cast? compressor wheels are the same. The garrett 56.5mm cropped turbine wheel in the GT2835 is based on the 60mm wheel but trimmed down, even though the centre takes up the same space. The GTX3071R kills a HKS GT2835 in every way. If I were to put one on an RB, I'd be using a .82 turbine housing, allowing more ignition timing to be run from the reduced back pressure and letting the engine make more power at lower boost.

A Tial MV-S 38mm v-band gate should flow enough on an RB25. I'd be getting an MV-R 44mm in case u want to upgrade cams down the track where the 38mm would start to fail to control boost.

The 60mm turbine wheel actually helps response though because there's more blade area to catch the exhaust gas at very little weight difference. The GTX compressor wheels are lighter but the 58 trim probably cancels that out. It's VERY unlikely that the GTX 3071's compressor wheel is heavier. Yes the .82 GTX3071R will be laggier than the .68 GT2835. 2 very different configurations. I bet the .63 GTX3071R would spool the same as the .61 GT2835 tho.

The GTX3071R would have about the same response and make a fair bit more power due to the new GTX compressor, full size 60mm turbine wheel and full size GT30 turbine housing.

HAHAHA

Yes

A GT4088R is only a little bit laggier than a T04Z because the GT4088R is a more modern turbo. Even that will be at it's very limits to make 800rwhp. Still too laggy for circuit IMO. The turbo I'd be looking at is the new GTX3582R. It flows similarly to a GT4088R but is a smaller, more responsive turbo. It's because of the new billet compressor wheel. A GTX3582R with a T4 twin scroll 1.06 turbine housing should make 700rwhp and an absolutely INSANE midrange. It'd hit boost early and hard and just PULL all the way to the redline. It'd definately FEEL faster than a GT4088R with 800hp.

Those 9.8:1 pistons sound ideal. A T04Z won't make 800rwhp. U'll need at least a GT4088R for that unfortunately.

that's fine. if budget doesn't allow cams, what i'm trying to say is get the turbo to suit. GTX3076R .82 will work best with stock cams and still max out the injectors!

Falken FK452's are the best street tyres IMO. They're simply AWESOME in the wet. I can supply them in 245/40R18 for $255 each. I can get Federal 595's cheaper but they're not that great on an ultra high performance car like a GTR. You really want the best when you have a GTR to make the most of it. Cheers, Brad tyres4less.com.au

Yep it'd work OK BUT a GTX3076R 1.06 with cams would be quicker on to boost, kick harder and make more power than a GT3582R .82 with stock cams.

Yes it will work with stock cams but it's FAR from an ideal setup. U may as well match everything properly because u'll end up with better response, better power or both if U do. A GTX3076R .82 would work very well with stock cams, be an absolute ANIMAL low in the revs still and max out 555cc injectors. Why go bigger if U can't make any more power out of the injectors? Also a GTX3076R 1.06 with 260 cams would kill a GT3582R .82 without cams for both response and power.

The 38mm gate wouldn't flow enough to control boost on a 25/30 with a GT3582R. Also, I know you probably already have the GT3582R but Garrett now have the GTX series so U could get a GTX3076R 0.82 and it'd smash a GT3582R for response and still make enough power to max out 555cc injectors. Looks like u'r running stock RB25 cams. I'd be running a GTX3076R .82 with that setup or if u want more power, get bigger cams, bigger injectors and run a GTX3076R 1.06. GT35 is too big for a setup with stock RB25 cams IMO.

Garrett -9 turbos will do the trick. They are the same as HKS GT-SS but cheaper. Great turbos. RB25's have 9:1 compression and VTC as well as being a lighter car which is prob why it was faster.

Next step - 10:1 compression and E85 LOL. Imagine how responsive it'd be then! That's a good figure for 98RON. What cams? (I'm too lazy to search or look at old threads)