GTScotT

So when will these be on the car?

I'd really love to get some seat time in such a setup as I'm struggling to find sufficient data for it online. Are you in Sydney?

A lot of assumptions are being made about my use case and probably my experience level, too. I didn't come to write war and peace, just to try legitimise the query so that people could actually talk about the new gen twins without being shut down with "twins in the bin" stuff. Originally when I was building my GTR I didn't imagine myself going down the paths I did, or owning more cars that serve other purposes. At that time the GTR was meant to be an all rounder, street and track duties and would only ever run on 98 (personal choice). I wanted to simplify the engine bay, make it easier to work on, max out what can be achieved on 98 ron while keeping the setup overall simple. Thermal management was a consideration and not overworking things, so smaller turbines were less desirable and made me steer away from the 7670 although it was a serious consideration. Compressor flow was also an issue as I didn't want to rev an RB26 to 6500 when it was made to rev to 8000 or more. On paper the IWG .92 T4 8374 looked like a great choice, and over time a motor rebuild with a sensible stroker kit and fancy cams (if not V cam) would spice it up a lot and make the ownership experience more special. Fast forward 3 years, numerous builds done for others and more cars in the fleet serving different purposes, I'm not feeling the big single vibe any more. If I went down the path I said above and added the V cam, built the motor, maxed out whatever it can do on 98, would I be in a net position higher than bolt on twins that justifies the expense? Going in circles now; likely no. If I was to put the car on ethanol and push high into the 400rwkw range I believe it would out shine twins being used for the same purpose - but that was never my intention. THAT SAID, my intention still warranted more than the average set of twins AND the advice was definitely that the single will do it better. With the experience gained over time and driving the car with the turbo in place of twins I am satisfied that a mid 300kw build should still consider twins and the GTIIISS are an interesting new gen option. Again I'll say, single was not all it was cracked up to be. Without spending a ship load more it left more on the table than desired and the obvious benefits were outweighed without pursuing the extra 100kw - which would also warrant the significantly more expensive twin external gate option. I should probably also note that I consulted some very big names on this before buying anything, and the consensus was landslide. The setup I have would outshine any bolt on twins at anything much over 300rwkw. At this point it did not, and I dont think it will. FS 8374?

As said I was building the car in stages and got side tracked. The 8374 went on ahead of time when the factory twins bust a couple of gaskets. The point is I was never chasing 400kw+ and it doesn’t seem like the cost benefit is there with this setup. The 8374 let’s the 26 rev past 8 as it should, but without a stroker or V cam it doesn’t come on well enough. -7s on the other hand will come on well enough and make over 300kw on an unopened engine, so really is it worth doing all the fancy stuff? Where I’m at right now is; probably not.

It’s simply where I stopped at the time. I was developing the car in stages and then bought a GR Yaris, so the GTR stayed at 1 bar longer than expected. As said, and to the point, the power at that level isn’t disappointing.. Its what it’s like to live with if not wringing it’s neck. The turbo comes on easily and drives well, has gotten me in a lot of trouble in the 3 years it’s been on the car, but again the standard R34 units make similar power and do it better in every way. I highly doubt me turning it up 10psi will make the driving experience better aside from the fact it will be a lot faster. 10psi more boost won’t make the turbo come on 1000rpm sooner, and another 5-10k on a V cam to do what R34 bolt ons do seems ridiculous (my engine is completely standard). I simply don’t want big power and converting to the single has showed me I actually just want a GTR in its natural GTR format with a few bolt ons. So I really understand the tone of the minority defending twins in this thread. I understand because I’ve done the thing and wish I didn’t.

I came across this thread looking for info on the GTIIISS and find myself reading another twin vs single debate.. If it means anything to anyone who still uses a forum.. I too watched the motive video of the 35R against the “-7s” and was sold. I then read the SAU gospel and witnessed the infamous “twins in the bin” meme. Unable to disobey the word of the lord our saviour, I installed the fabled 8374 at considerable cost and have unfortunately resigned to the fact that it’s not all it’s cracked up to be. The Motive video in question alludes to the fact that the -7s are high flowed but doesn’t give any specs. The car makes 500whp in the video, more than what -7s should make. It’s anyone’s guess what the specs are or how those twins actually perform.. Meaning the video could be showing that half ass twins aren’t as good as a 35R. Like much of the GR Yaris content from the same source.. A crock of shit. I’m running a bar of boost through my 8374, the car is fast.. But my friends almost identical GTR running a bar of boost through R34 twins is faster. More under the pedal, more when you want it, more over a wider spread. I’m certain if I threw another 40 grand at the car I could see the 500rwkw that would make the 8374 show how amazing it is compared to other 500rwkw turbos.. But it’s not the “better in every way” dream this forum and the internet at large portrays it to be. I find it really difficult to find information from Japan, but I have seen a lot of evidence that Japanese tuners are reverting back to twins and aiming for less power. This brings us to the GTIIISS… I am still legitimately interested to know if they would be better than -9s, and if so by how much? Another thing I am curious of is if a smaller single would keep the simplicity but give back the drive. Adam LZ did the video of the G30-770 on his VCT equipped RB, the graph shows it standing up at 4 and the driving scenes aren’t much different. Perhaps better than the bolt on 8374.. But not by much. Keen to discuss sub 350kw 98 only RB26.

Any dyno results? Was damaged perhaps caused by excessive EGT?

I've fitted many of these and have never changed carrier. Use your stock 18mm carrier.

*prepares lowly slung balls for deployment*

Firstly, do your cams and head allow for more? By my eye I think the nose over is more mechanical than it is in the turbine housing.

The mamba housing in question is a good unit, not a compromise and will perform no different from its T3 counterpart. For best results in the compromises you have mentioned use a GTX based 71mm compressor. The 71mm GTX is native to a T04B in the GT28 series units so it will work.

How did you go with this mate? Also have a GTR which is currently stock with a PFC and TBE. Planning to single sooner rather than later, but won't be building the motor for quite a while so am happy to keep it simple with the PFC. A single R35 AFM would make things super simple and dirt cheap while the cars still at a very basic level.

Attached is an extrapolated guide you can use with the 9180 comp map. You can see I've married up your existing results and PR by using the VE as a variable, it's actually still very realistic and what I'd expect from a 1J with decent intake and exhaust manifolds. You can see you'll hit 700 by 30psi, and that should be achievable with the motor in its current configuration. However, the turbo has a lot more in it that your existing results show would require changes to the head and cam combo. IE 800 is accessible but you'd need to turn it well into the 8s. Hope that helps.

Guessing by the heat marks on only one side of the flywheel your car got locked in gear a lot and that's why you're selling the clutch? You're welcome.

Will be fitting a 550.72wg to a very basic config SR20VET later this year. Low comp, P11/VET cam combo, franken DET/VE intake, hypex ex side. Will try access above 8000 RPM on Piss98. Hope to move close to 50lbm. Yes, Lithium, I am still alive. I also have an R33 GTR. Posting for sake of what they look like in the flesh. This was the first one delivered to a customer in Aus (me). It is a highly finished product compared to last gen, I have handled all manner of GTX and EFR in the last 2 years and can say these are the prettiest. I hope it's pretty good rather than pretty average. Stay tuned.

Got that back to front man, advancing the exhaust cam means the exhaust closes sooner and the there is less overlap when the intake opens. In my case reducing overlap worked wonders. More vacuum on idle and a lot more lively off boost.

You should definitely consider changing cams or fiddling with timing on these. If you haven't already I would be advancing the exhaust cam at least 4 degrees to try and reduce that overlap. How you will test for valve contact on high lobe before actually running it though, I have no idea. Within a few hundred RPM I have a comparable result to you, except mine has more midrange and I am running a far less exotic setup. GTX3071R, S14 DET with non VCT cams, 98 ron, 295rwkw peak, 280kw mid 4k on a DD roller. I attribute my result to the cam profile (256/11.5 Poncam). For a VET setup with functional VVL, E85 and a EFR 7163 I think there is more to be desired. I would definitely visit the cam profile, and/or the timing. Remember to reduce overlap by advancing exhaust and use the intake to determine your powerband. In this case I think the little EFR is getting wound up a fair way and even the intake cam could be advances 2-3 degrees. Remember to offset whatever you advance the intake to the exhaust when you consider overlap. Hope this helps!

Interesting feedback re GTX3071 vs GT3076, who exactly said this? I believe Mick_O was the fabled GTX response king around these parts, never had I heard anyone say his car was less responsive than an equivalent GT3076.... Furthermore, I can confirm that I've driven a bunch of 3076 powered SRs and none compare to the response I am getting from my GTX3071. None of those 76s were twin scroll but neither is mine. Apples and apples. First hand experience > folklore, wouldn't you say?

Get a 71GTX mate, regardless of what housing you run. Near enough GT76 flow, near enough or the same as GT71 spool. Am running a GTX71 on my SR and cannot fault it. It makes 295wasps on a DD running 98 ron and it is by far the best turbo all round that I have had, period. My personal recommendation: get a GTX3071R core without housing and a Kando 10cm T3 Vband housing. Kick ass and take names.

The kando 10cm is 1/3 of the price and gives you an inbetween size (.7x) I've used the kando 12cm (.89) on a GT30 core and so far have found zero drawbacks. I have also seen a few in action and results indicated they did exactly what the specs implied. Far better value in total if you buy a garrett CHRA and kando housing separately.

At least theres a couple of us still winning on 98. My knock threshold seemed to be up around the 27psi mark. Makes the hassle of E85 a lot less appealing than it already was. .82 open to 1.05 divided; am not too sure much could be attributed to top end power, I think they would lay in a fairly similar area. Though I'd believe the T3 variant of the 7670 would compress the left hand half of the curve a few hundred RPM. Still noteworthy as it is really winning on power for 98. Am curious what sort of turbine speeds would be seen from a healthy 3L on the T3 open... I may be conjuring something of that spec sooner than expected. Lucky you found that. As clued as everyone on here is I highly doubt anyone would have known off the top of their head.

That core definitely has MHI linage. Might be an SLSS2 rather than an SS2, Stao to confirm?

Jus to confirm; the HTA was T3 open, was it not? I just want to make sure I'm looking at the thing correctly. Don't want to mislead myself in case this isn't apples and apples.

Yeah they are just cast. I used Penrite HPR5 which is a 'full zinc' oil which is whats required for proper camshaft run in. I ran the motor for a good 30 minutes with varying RPM before cool down and then restart. By my knowledge thats the right way to do it, however slightly less pedantic. Anyhows, thats the report and my personal opinion based warning. I am just guessing here but I have heard talks that Japan has had materials shortages due to shipping issues post tsunami. Now its also been speculated that these parts are made elsehwere in the world but this is the general gist of what I am starting to form. Not wanting to fear monger anyone but I am definitely keen to change to an American supplier. Despite the fact they would be made in China products I am more confident in the QA requirements set out by the brand. Thems the feels anyway.

Sorry about the confusing babble guys. The lifters were not a tomei product, they were an aftermarket replacement sold as a upgrade for SR20s (upgrade my ass). The lifters are to blame for my second failure however I would have really thought the cams would survive some noisy lifters for the drive home. Never have I seen a set of cams get flat spotted from noisy lifters.. And I have heard some horrible lifters. My cams are Tomei 256 Type R for S13 SR20DET. This report/warning is made on the basis of the coincidental 'supply issue' and a pair of cams not durable enough to cop < 1hr use with noisy lifters. I do believe they should be more durable than this. I hope that clears it up.