Lithium

Sounds like a lot of fun! Though definitely sounds like its in between the GT30R and GT35R in terms of spool, won't comment on power until you get it on a dyno - is this due to happen anytime soon?

Yeah, you definitely don't want that.

I was given this same run around a few years ago when trying to buy my true GT3076R - everyone kept pointing me at the T04S covered version with the different compressor wheel, I even provided them with the CHRA reference to make sure they gave it. I tried a guy who uses an Australian supplier they swore by (SAU Sponsor too I believe) and they at best glanced at it and told me "That version has been phased out, this is the newer/better one". Anything to make a sale, eh? I ended up buying my REAL GT30R from ATPturbo.com, never looked back.

Yeah that size stuff was the deciding factor on me going GT30R instead of HX35, I had one right there to go with but wussed out - the GT30R is enough of a bitch to work around if I need to change gaskets etc haha.

Nice thats no small amount of power - is that on pump gas or race gas?? Whats spool like?

Yeah definitely, we're all really hypothesising I see what you are saying and not really too sure it would cause that much compromise - you'd pick the a/r to suit the fact its a split pulse housing... ie, with twins you'd maybe go .64a/r whereas on a single you'd be looking at .95-1.06. Gases are inherantly good at being squeezed/forced places, so I am sure that the divide facing the turbine isn't going to worry them toooo much given that they are basically being forced at a bunch of spinning blades and are bound to expand, squish and swirl in all sorts of weird ways anyway. I also like the fact that with the twin scroll setup there is a constant stream of pulses hitting the turbine, it will always have leverage on it whereas each of the twins will potentially have a far greater oscillation pre-turbine due to the gap between pulses. I really don't know for sure though, though its interesting to ponder. The twin scroll setups I have been exposed to honestly have blown me away in terms of response and spool, though I have never been in a car with twins that is using a similar engine spec and power level to another car running a twin scroll single to give a fair comparison. I have however been in GTR running a single scroll .82a/r GT35R making similar power (getting towards 400kw @ wheels) and similar engine spec to ones running twin GT2530s and I reckon the GT35R setup was more responsive (at worst equivalent), so given the range of advantages a twin scroll 1.06 T4 setup on the same car would bring I dare say there would be no comparison between such a setup and a pair of GT2530s. It may not be apples and apples though as I suspect GT2530s might be capable of making more power.

Which is what you want? The turbine gets the full force of both.... without any "mess" from collisions before hand I am not actually sure what to really expect, it would be interesting to know how they would compare but I personally can't see any obvious reason why twins would be more responsive. To be honest I'd almost expect a single to be a bit better in overall efficiency. The twins have a bit of a bonus in that they can have REALLY short runners, thats about it that I can think of.

Guess it depends on what you started with and what you want from it etc. If you go a twin scroll T4 based turbo upgrade you potentially don't have to change much in future, you have a more efficient setup (nicely designed manifolds/external wastegate setup), the engine bay is much more maintence friendly etc. And of course there is the whole obvious fact its just cooler

You're definitely not the first to notice the fact the sets of 3 cylinders are separated in the factory log manifold, I've pondered it and decided that I'd still rather use a custom manifold if I went to a larger twin scroll turbo though it is interesting to note and I am sure it has its advantages even with a single entry turbo. I look forward to hearing how the HX35 goes as I got SO close to getting one for my own Skyline years ago before I ended up settling on the GT30R.

Talking about GTR or GTS25t? My Series 2 25T hit 10psi by ~2500rpm with intake/exhaust.

That is awesome, congratulations!!! Look forward to hearing how they go for you

I just gave it kinda firm knocks on my workbench and a feeler gauge to verify the gap - seemed to do the trick fine.

Awesome cheers for sharing - very keen to hear how the 6262 goes on it Any chance of overlays of any of the different turbos?

You should really add what you want to know about the T51R. From your post you aren't worried about spool etc, so thats good as there won't be much - and you want >500kw which is what a T51R will do fine as well. What is it you DO need to know about it? It might help you get some more constructive responses - especially if you give some input on what your intended engine build spec is, you are still using the 25 block? Fully forged etc? What fuel will you be dyno queening on?

6boost manifolds that I have heard result in a more tuned pitchy note, sounds awesome. If you don't like it - give it to me

I think the reason for this is a lot of people have treated them with a certain amount of contempt being the potential mismatch scenario which DiscoPotato also mentioned. I personally would much rather just go either GT3582R or GT4088R those two and the GT3788R were the only choices. Discopotato - The GT4082 uses a less trim comp wheel than the GT3582R, people seem to often fall short of even a GT3582Rs power potential with them though that could be a side effect of them being mainly bought by people looking for a bargain and as such not being willing to spend the money to get the entire setup. I had a GT4082 which I obtained for under NZ$300 last year and on a 2.5 with a twin scroll manifold it was making 1bar by 4500+rpm, BB core would bring it in a bit sooner but I'm not sure why I'd go one over the GT35R. By dopey you mean unresponsive? Imho if with a setup you are going to have a GT4088R being unresponsive, then I am fairly sure that a T88 would be that and a whole bunch more. I would love to have had exposure to a GT4088R setup but in this part of the world it seems they are a very uncommon mix though the UK and some US Supra guys seem to LOVE them on a street/track setup though they are using 3litre engines. With a stock displacement RB26 you are going to always be exposed to a certain amount of lag, if you are aiming for 450kw @ wheels then in my opinion you should really be expecting to have to live in the 5000+rpm range to keep it full on the boil. Which fuel are you intending on running it on?

Sorry I completely missed that question. Umm the GT3788R I'm not so sure about, as it is the GT4088R and GT3582R seem pretty close to each other in performance and I'm not sure what the GT3788R is supposed to achieve. I had in my head it was for diesels, and has been used on them for some time - though it seems a bit reminiscent of the GT3082R - trying to make a good proven combination spool a little bit better by putting on a smaller turbine wheel ends up often just being a mismatched turbo. What power targets are you looking for, and spool level are you willing to live with so that you started looking at the GT3788R? ForcedPerformance in the states have a range of pretty swish turbos which fit between GT3582R and GT4088R size, and a couple of people have used Precision 6262 and 6765 turbos on 2.5-3litre 6s (Nissan and Toyota ones) which pretty good results which I am still looking into. The Precision 6262 is one which sits between GT3582R and GT4088R area and seems to be too good to be a true, an EVO 8 in the States running a T3 flanged one ran an 8.9 with full interior on E85 running one recently! If the hype turns out to be true, one of those with a decent T4 twin scroll setup on an RB26 like yours could be an unbelieveable street setup.

Would love to be able to tell you, the whole trick here is its not that common a combination. In the instance of that 300ZX I posted a link to the thread about, he gained around 30kw when tuned to where they could safely take the timing on a T04Z setup but its a whole different car.

Yeah thats correct, you need to keep each pair of cylinders as separate as possible - ideally running twin wastegates though thats where you really start getting into perfectionism Here is a pic down into the collector of a good twin scroll T4 exhaust manifold made by Kyle of 6boost: And a twin scroll T4 turbine housing as I haven't quite been able to ascertain from your posts if you know exactly what it means: So the pulses from the two sets of cylinders are kept completely separate until they hit the turbine wheel

Yeah, have heard the same thing speaking to tuners - I find it a bit frustrating when they stay at timing levels they are used to on a setup which is clearly good enough that it can take noticeably more before it starts getting dangerous. If it were me on my own car I'd leave the same margain of error and enjoy the fruits of a more knock resistant setup

I wonder what the odds are it was my post you are referring to. The 1.06 T4 twin scroll I am pretty sure is more of a recent thing to become available, .63, .82 and 1.06 remain to be the "typical" GT3582R turbine housing options. The main disadvantage to single scroll turbos on 6cylinders in my opinion is the fact that you have 6 pulses which when fed into a common collector allow no gap between each other and as a result of which end up colliding - this generates pressure etc which is not really used for any great advantage other than having messy gas flow where all the cylinders are trying to breathe through. This means energy isn't used optimally to spool the turbo and can result in increased manifold pressure which does nothing other than make life more difficult for the engine to flow nicely. It just so happens that the firing order of RBs is such that cylinders from the front three and rear three are always fired alternatively meaning if you collect the front three and rear three separately - instead of colliding with another pulse going through the collector, each new pulse is much more likely to hit the low pressure zone which always trails an exhaust pulse meaning instead of having extra effort to "push" gas out the valve there is chance of something relating more to a scavenging effect. This basically means the exhaust energy is used much more efficiently, which can both spool the turbo better and also reduces manifold pressure meaning that for an equivalent flowing turbine the engine can tend to take more timing before hitting a knock condition (meaning potential for more reliable power!!). This kind of advantage is in my opinion twin turbos can be seen to perform "better" than singles in terms of response and spool on RBs, I believe its more to do with the more efficient use of exhaust energy than anything else and that advantage is completely negated by a well designed twin scroll turbo setup. Some people I know and I have been discussing this for some time, and the general feeling so far is that an equivalent a/r TS turbine housing on a 6cylinder turbo motor seems to allow more power to be made than with the single yet also spool a few hundred rpm earlier. I'd expect a TS 1.06a/r housing similar to or better than a .82a/r single scroll one on a GT35R, but have a higher power potential on an RB but this is purely speculative as I've not seen any results from such a combination. Here is a link to a thread about someone who I ended up convincing going to a twin scroll setup on their 300ZX after messing around for some time trying to get a good compromise between lag and power: http://forums.toyspeed.org.nz/viewtopic.php?t=71870 Atpturbo.com sell Garrett GT3582Rs with 1.06a/r T4 twin scroll and .78a/r T3 twin scroll options. Hope that helps

Would be awesome to see a 1.06a/r T4 twinscroll GT3582R setup on an RB30DET (or any decent RB), I have that sneaking suspicion it could be a match made in heaven

I'm guessing you mean in Australia?

Yeah it can have an effect on the engine in the relative scheme of things, the turbine housing and wheel are TINY and at that boost level the pressure and heat in there will go through the roof. That ends up with a much higher chance of reversion, and reversion raises the cylinder temperatures something crazy - high cylinder temps are what increase detonation and ultimately can speed up the wear and tear of the engine. I partly upgraded my turbo as I wanted to go a bit quicker but was already at 10-11psi on the stocker, as far as I am concerned running >250kw @ wheels on a big turbo on 1bar is FAR nicer on the engine than running just over 200rwkw on the stock turbo on the same boost level despite the higher power level. You would be surprised at how little extra force is put on the bottom end by running a decent matched turbo on 1bar with a good tune versus the stock turbo on similar boost, if not a bit less. Making more power on the 1bar with a decent turbo using the standard rev limit and good tune is the definition of having your cake and eating it too with an RB25DET, if you are looking for a bit more power out of your stock internals. Just my opinion, anyway.

You're right, boost isn't everything (I wouldn't say nothing by any stretch of the imagination) but I would be far more confident of running a T88 on the side of my stock engine at 1bar than a stock turbo. The T88 will have far lower turbine pressure and heat from an overworked compressor than a stock turbo and will not magically make stupid power just because a T88 is a big turbo, the big power numbers on low boost seen on some engines running T88s are partly as a result of the big cams and revs that the engine has been built to use to rev high enough to justify the bigger compressor.